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Discover cutting-edge information that affects your health. At Physicians Lab, we strive to ensure you have up to the minute information to help you better care for your health and achieve optimal wellness. From the latest developments in medicine to dynamic statements on healthcare issues, you will find a wealth of knowledge here.

Download the Estrogen Interpretive Guide here

Trouble With The Curve:  It’s Not Just a Movie

A practitioner’s approach to the cortisol curve

 By: Benita Phillips, D.O.

 

How many times have you looked at a patient’s cortisol curve and said to yourself:

“That just doesn’t make sense!” 

And you think:

“This person should feel fine…”

Or the contrary:

“How does this patient even get out of bed?”

And then you see it, the dreaded up and down zigzag pattern of cortisol levels all day long, fluctuating faster than gas prices on a holiday weekend. And all the while you’re wondering why their symptoms don’t match the curve – they’re supposed to!

What We Knew

We were taught to treat adrenal dysfunction based on 4 or 5 cortisol levels measured throughout the day, called a diurnal curve.

We were taught to use certain supplements to treat high cortisol levels and certain supplements to treat low cortisol levels.

We were taught to use certain supplements for patients who had a cortisol curve that looked like the rickrack my grandmother sewed onto my homemade clothes as a child.

We learned the symptoms of adrenal dysfunction.

We learned that high cortisol causes things like anxiousness and cravings for sugar and carbs, and we learned that low cortisol causes symptoms like fatigue and salt cravings.

But what can be confusing and frustrating are those cortisol levels that do not explain the symptoms – or worse yet – the patient whose symptoms do not resolve with the supplement designated for their cortisol levels.

What We Know, Now

Enter Physicians Lab and their 24-hour urinary hormone testing.  The report includes not only the standard 5-point cortisol levels and curve but also includes total cortisol metabolites; the cortisol:metabolite ratio and a 5-point cortisone curve (an adrenal game changer!).

Now we can see not only the cortisol curve, but we can also see how each patient metabolizes his or her cortisol.  This is especially important for those patients whose symptoms do not match their cortisol levels.

In addition to studying the individual cortisol values and the diurnal curve, it is very imperative to look at the cortisol:metabolite ratio.  As long as this ratio is in the mid-target range (best being 1), then you know that the reported cortisol levels can be interpreted as is.  Meaning they are true and accurate levels.

However, if the cortisol:metabolite ratio is elevated, then the patient is not metabolizing cortisol well.  He or she has a decreased cortisol metabolism.  This may indicate that the actual cortisol levels could be misinterpreted as the result of increased adrenal production.  The levels may be falsely high.

If the cortisol:metabolite ratio is low, then the patient has increased metabolism of cortisol.  This can cause cortisol levels to be misinterpreted as the product of decreased adrenal production.  The levels may be a false low.

Careful Considerations

At this point, we need to remember that abnormal cortisol metabolism changes only the height of the curve.  It is important to note that an abnormal cortisol metabolism does not change the shape of the curve. The shape of the diurnal curve is still the best way to assess adrenal health and function throughout the day.  Let the shape of the curve guide you in your decision process for supplement use.

We also need to remember that decreased cortisol metabolism is often the first indicator of hypothyroidism.  And, an increased cortisol metabolism (false low curve), indicates that the patient is at high risk for obesity, metabolic syndrome, insulin resistance, and type 2 diabetes.

Supplemental Solutions

Lifestyle changes, as well as carefully chosen supplements, are essential for adrenal health. The following lifestyle changes are imperative for the patient with adrenal dysfunction of any kind, no matter what the trouble with the curve:

  • – Healthy diet with an emphasis on vegetables and some well-chosen fruits. Think berries!
  • – Daily exercise
  • – Stress reduction techniques
  • – Sufficient, quality sleep
  • – Daily supplements – fish oil, multivitamin, vitamin D, probiotic

With so many quality adrenal supplements available at our fingertips to help treat different adrenal issues, below are three of my favorites:

  • – Pure Calm – for truly elevated levels
  • – Pure Lift – for truly low levels
  • – Adapto-Pure – for that zigzag pattern

 

The good thing is that if you have questions about your patient’s results, the friendly folks at Physicians Lab are ready and willing to help interpret results, so you have a clear understanding of what is going on. They can be reached Monday-Friday at (877)316-8686, option 2.

 

 

Benita Phillips, DO received her doctorate of Osteopathic Medicine at Oklahoma State University’s College of Osteopathic Medicine in 2000. She went on to complete her residency in Family Medicine at the University of Oklahoma College of Medicine in Tulsa, where she earned the honor of Chief Resident in back to back years (2002-2003). In 2003, Dr. Phillips became Board Certified by the American Board of Family Practice and was awarded both The Paul E. Tietze Memorial Award for Commitment to Patient Care and the Keeping Up With the Times Award for Research Excellence. She later was presented with the Physician’s Recognition Award by the American Medical Association in 2007. Dr. Benita Phillips is an active member of the fellowship in Regenerative Medicine and the American Academy of Anti-Aging and Regenerative Medicine (A4M). She is also an active member of the American Medical Association and the American Academy of Family Physicians.

Short Communication: Implications of Flaxseed on Urinary Hormone Testing

By: Clifford Morris, Ph.D. Cand., Chief Chemist and Research Scientist

 

Flaxseed and Phytoestrogens

Flaxseed is a powerful plant that has achieved massive interest, yet much of what people know about flaxseed is simply misunderstood. Flaxseed is a popular dietary source of lignans, which are a type of phytoestrogen.1,2 A phytoestrogen is a plant nutrient with structural and biochemical similarity to estrogens. Many plants including soy, sunflower, and sesame contain phytoestrogens. Whole flaxseed is the richest plant source of alpha-linolenic acid (ALA) and the lignan, secoisolaricirescinol diglucoside (SDG).3 Flaxseed also contains a significant number of other macronutrients, fiber, and minerals. ALA is converted to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which are anti-inflammatory and cardioprotective, while SDG is converted to enterolactone (EL) and enterodiol (ED) which have anti-estrogenic and antioxidant properties.4–6 Phytoestrogen compounds found in flaxseed act closely to estrogen blockers; by modulating the production, availability, and metabolism of endogenous estrogen, specifically 2-methoxyestradiol, estradiol and 17 beta-estradiol.7–10 SDG in flaxseed can lower the production of estradiol by blocking the aromatase enzyme, similarly to aromatase inhibitors, as well as having a higher affinity for estrogen receptors than almost all the endogenous estrogens.11

 

Flaxseed and Breast Cancer

Lignans are the center of the controversy regarding whether it is safe for women with breast cancer to consume flaxseeds. Since the phytoestrogens in flaxseed can act as or block estrogen, this has raised concerns about whether phytoestrogens may not be safe for people with a history of hormone-linked cancers, such as prostate cancer, endometrial cancer, or estrogen receptor positive breast cancer.  In postmenopausal women, lignans can cause the body to produce less active forms of estrogen. This is believed to potentially reduce breast cancer risk.1,7 There is evidence that adding ground flaxseeds into the diet decreases cell growth in breast tissue as well.3,5 Again, this would be the type of change that would be expected to decrease breast cancer risk. Research provides evidence that flaxseed can increase apoptosis. Cell and animal studies have shown that two specific phytoestrogens found in lignans, EL and ED, may help suppress breast tumor growth. Animal studies have shown that both flaxseed oil and lignans can reduce breast tumor growth. 4,6,7,12 Combined, this suggests that flaxseeds may have anti-cancer benefits. It is recommended that human intake should be through diet only, not supplementation. If you plan to add flaxseeds into your nutrition plan, please talk to your doctor first to ensure it is an appropriate choice for you.

 

Flaxseed and Urinary Hormone Testing

Consumption of flaxseed influences estrogen metabolism, as indicated by both urinary metabolite excretion and serum hormone concentrations. Studies have shown that flaxseed lignans moderately inhibit the enzymes aromatase and 17 beta-hydroxysteroid dehydrogenases, which catalyze the conversion of androgens to estrogens and balance between estrogens, respectively.2,9,10 Flaxseed consumption has also been shown to affect both endocrine and growth factor pathways by modifying steroid hormone metabolism of IGF and EGFR. Since flaxseed alters estrogen metabolism and could change the clinical interpretation of an estrogen profile, it is strongly advised that flaxseed and phytoestrogen consumption be avoided for at least 3 days prior to urinary hormone testing with Physicians Lab.

 

 

References:

(1)         Flower, G.; Fritz, H.; Balneaves, L. G.; Verma, S.; Skidmore, B.; Fernandes, R.; Kennedy, D.; Cooley, K.; Wong, R.; Sagar, S.; et al. Flax and Breast Cancer : A Systematic Review. 2014.

(2)          Brooks, J. D.; Ward, W. E.; Lewis, J. E.; Hilditch, J.; Nickell, L.; Wong, E.; Thompson, L. U. Supplementation with Flaxseed Alters Estrogen Metabolism in Postmenopausal Women to a Greater Extent than Does Supplementation with an Equal Amount of Soy 1 – 3. 2004, No. 1, 318–325.

(3)          Mora, C.; Tomaz, C.; Ana, S.; Gustavo, A.; Costa, V.; Ibrahim, P.; Maria, N.; Costa, B. Comparative Effects of Brown and Golden Flaxseeds on Body Composition , Inflammation and Bone Remodelling Biomarkers in Perimenopausal Overweight Women Q. J. Funct. Foods 2020, 33 (2017), 166–175.

(4)          Lindahl, G.; Saarinen, N.; Abrahamsson, A.; Dabrosin, C. Tamoxifen , Flaxseed , and the Lignan Enterolactone Increase Stroma- and Cancer Cell – Derived IL-1Ra and Decrease Tumor Angiogenesis in Estrogen-Dependent Breast Cancer. 2011, 51–61.

(5)          Gray, S. L.; Lackey, B. R. Optimizing a Recombinant Estrogen Receptor Binding Assay for Analysis of Herbal Extracts. J. Herb. Med. 2018, No. August, 100252.

(6)          Truan, J. S.; Chen, J.; Thompson, L. U. Flaxseed Oil Reduces the Growth of Human Breast Tumors ( MCF-7 ) at High Levels of Circulating Estrogen. 2010, 2, 1414–1421.

(7)          Jelodar, G.; Masoomi, S.; Rahmanifar, F. Hydroalcoholic Extract of Flaxseed Improves Polycystic Ovary Syndrome in a Rat Model. 2017.

(8)          Hutchins, A. M.; Martini, M. C.; Olson, B. A.; Thomas, W.; Slavin, J. L. Flaxseed Consumption Influences Endogenous Hormone Concentrations in Postmenopausal Women. 2001, 39 (1), 58–65.

(9)          Sturgeon, S. R.; Volpe, S. L.; Puleo, E.; Bertone-johnson, E. R.; Heersink, J.; Sabelawski, S.; Kristina, W.; Bigelow, C.; Kurzer, M. S. Effect of Flaxseed Consumption on Urinary Levels of Estrogen Metabolites in Postmenopausal Women. 2010, 62 (2), 175–180.

(10)        Sturgeon, S. R.; Heersink, J. L.; Volpe, S. L.; Bertone-johnson, E. R.; Puleo, E.; Stanczyk, F. Z.; Kristina, W.; Kurzer, M. S.; Bigelow, C. Effect of Dietary Flaxseed on Serum Levels of Estrogens and Androgens in Postmenopausal Women. 2008, 60 (5), 612–618.

(11)        Mccann, S. E.; Edge, S. B.; Hicks, D. G.; Thompson, L. U.; Morrison, C. D.; Andrews, C. A Pilot Study Comparing the Effect of Flaxseed , Aromatase Inhibitor , and the Combination on Breast Tumor Biomarkers Kim Clark and John Wilton. 2014, 66 (4), 566–575.

(12)        Dikshit, A.; Hales, K.; Hales, D. B. Whole Flaxseed Diet Alters Estrogen Metabolism to Promote 2-Methoxtestradiol-Induced Apoptosis in Hen Ovarian Cancer ☆ , ☆☆. J. Nutr. Biochem. 2017, 42, 117–125.

 

The Role of CBD in Maintaining the Endocannabinoid System and HPA Axis Balance

By: Clifford Morris, Ph.D. Cand., Chief Chemist and Research Scientist

 

In this article, we will shed light on the nebulous topic of cannabidiol (CBD), including the effects of CBD on the Hypothalamic-Pituitary-Adrenal (HPA) axis, stress, and inflammation. The legalization of medical cannabis has brought a new wave of cannabinoid science and healthcare to the world, and CBD has exponentially grown in popularity as a dietary supplement.1–5 One of the reasons for this boom is that CBD can assist the body in maintaining homeostasis – the fine art of balancing hormones, immune functions, metabolism, sleep, and stress responses.6 Society is plagued by chronic stress and inflammation caused by poor health and diets, overworking, low quality sleep and negative environmental impacts. It is a global pandemic that must be addressed, as it exacerbates the pathology of cancers, neurodegenerative diseases, heart attacks, diabetes, obesity and many more. The majority of these contemporary issues could be a consequence of the prohibition of hemp and cannabis under the Marihuana Tax Act of 1937.7 For thousands of years, humans have epigenetically coevolved a dependence on hemp, but in 1937, Americans experienced a sudden and total starvation of cannabinoids due to the prohibition of hemp.8 Is this endocannabinoid crisis one of the major causes of modern chronic illness? It certainly could be.

 

The Endocannabinoid System (ECS)

CBD is one of many cannabinoids extracted from the industrial hemp plant, Cannabis sativa. Another famous cannabinoid is tetrahydrocannabinol (THC). However, CBD has unique properties that make it attractive for therapeutic purposes over THC. Recently, in January of 2019, the Farm Bill removed CBD from the Federal list of regulated substances. From a pharmacologic perspective, CBD has no obvious intoxicating (psychotropic) effects as well as no chance of excitotoxicity, both of which contribute heavily to therapeutic decision making.9,10 This leads us to discussing CBD’s mechanism of action.

(11)

The endocannabinoid system (ECS) is a biological network distributed throughout the entire body. It is composed of endocannabinoids, which are endogenous lipid-based retrograde neurotransmitters that bind to cannabinoid receptors and proteins that are expressed throughout the central nervous system, including the brain and peripheral nervous system.4,6,12 The ECS is comprised of two important receptors; cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2). CB1 and CB2 are transmembrane G-protein coupled receptors (GPCRs) located throughout the central and peripheral nervous system. They are the most abundant GPCRs in the nervous system and work with cannabinoids to maintain the homeostasis of the cell. The ECS also contains arachidonate-based endocannabinoids, known as anandamide (AEA) and 2-arachidonoylgycerol (2-AG), along with enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), which break down AEA and 2-AG, respectively.

 

Effects of CBD on the HPA Axis and Stress

The HPA axis and ECS act in concert, balancing and regulating a variety of physiological and cognitive processes including homeostasis, metabolism, inflammation, pain-sensation, mood, memory, and many more.6 Interestingly, THC can bind to CB receptors directly, with a preference for the CB1 receptors which are more densely located in the central nervous system and thus the source of THC’s psychoactive effects. However, CBD interacts indirectly with other cells that then interact with these receptors and others, manipulating cellular function.1 CBD is a competitive inhibitor that binds to FAAH and MAGL, with a higher affinity then 2-AG and AEA, resulting in an elevated concentration of AEA and 2-AG in the body. Increasing endocannabinoid levels in the body allows the ECS to do its job well, maintaining balance through times of change or stress.4,6 The fight-or-flight response, also called acute hyperarousal, is a physiological reaction that occurs in response to perceived (real or not) threat or stressor.13 In brief, an external stress signal is perceived by the cerebral cortex, initiating the hypothalamus to produce corticotrophin-releasing hormone (CRH), which in turns makes the pituitary gland produce adrenocorticotropic hormone (ACTH), cascading to the adrenal glands and finally resulting in the production of cortisol, epinephrine, and norepinephrine. This allows the body to respond in a heightened state, but chronic activation of this system can lead to permanent damage. There are also areas in the hippocampus and amygdala which are densely covered in CB1 receptors. The amygdala’s main role in the body is intelligence and processing emotions, most notably stress, anxiety, fear, and PTSD.1,2,4 Physiologically, most stress and anxiety is a result of the bed nucleus of the stria terminalis (BNST) coordinating a stress-based response in conjunction with the amygdala. Here, CBD produces its anxiolytic effects via activation of the 5HT-1a receptor associated with serotonin, as well as the BNST of the amygdala. It is important to note that CBD only mildly increases AEA concentrations. This is shown to give enough stimulation to decrease FAAH levels, as well as the neurotransmitter glutamate, thereby relieving stress and allowing the brain to respond to stress effectively.

In cases of chronic stress and inflammation, both the HPA axis and ECS are imbalanced and dysfunctional. It is critical to address the endocannabinoid shortage and rebalance the HPA axis. The ECS can be rectified by lowering CRH and FAAH with exogenous cannabinoids, such as CBD, thereby raising AEA and lowering glutamate.3,5 Increased levels of AEA are directly correlated with improved wellness, mood, and stress response. The HPA axis can be rectified by focusing on lowering cortisol and CRH levels through stress, diet and sleep management. Piecing it all together, CBD is an excellent way to boost endocannabinoid signaling, improve the regulation of the HPA axis, and promote a healthy endocrine system. CBD naturally increases ECS tone which helps to improve the regulation of homeostasis across the HPA axis. Physicians Lab offers comprehensive diurnal hormone testing to determine cortisol and cortisol metabolite levels, and address the sources of HPA axis dysfunction. This will improve both the physiological and psychological responses to stress, making a person more likely to resist the cascade leading to HPA dysfunction and endocrine-related health problems.

 

Neuroprotective and Anti-inflammatory Properties of CBD

CBD also has anti-inflammatory and neuroprotective effects.4,5,9,14 This, however, is achieved without involving the endogenous cannabinoid receptors. A major component of inflammation is the response to reactive oxygen species (ROS), which can accumulate and cause DNA damage and cytotoxicity. Antioxidants are molecules that have the ability to detoxify ROS. CBD has been shown in various studies to have a much higher antioxidant ability than vitamin C and E, and comparable to that of BHT – a synthetic antioxidant used as a food and drug preservative.14 In addition to acting as an antioxidant itself, CBD causes a noted increase in the presence of other antioxidants as well. CBD upregulates an important antioxidant, glutathione, as well as the enzyme superoxide dismutase (SoD), which is the body’s strongest antioxidant and responsible for around a third of the total antioxidation in our bodies. Earlier we mentioned glutamate, which is the brain’s primary excitatory neurotransmitter. When glutamate levels are too high, excitotoxicity and oxidative stress both occur. CBD is shown to prevent this by agonizing serotonin 5-HT1a receptors, which have the opposite effect of glutamate receptors, thereby reducing excitotoxicity and oxidative stress.10 Many neurodegenerative diseases are characteristic of excitotoxicity, including Alzheimer’s Disease and Parkinson’s disease, anxiety, schizophrenia, and even autism. Finally, CBD is fast becoming a treatment of choice for effective pain relief, spasticity and seizures, with plenty of high-quality evidence supporting it.4,5,15 CBD’s action as a protectant against inflammation and oxidative stress could explain the success that many have found using CBD to add to their therapeutic strategy for these conditions and others.

 

Supporting Balance with CBD

In conclusion, CBD is a non-toxic, non-psychotropic, powerful dietary supplement that can help maintain ECS and HPA axis homeostasis. It supports lower levels of stress, anxiety and inflammation, along with antioxidant and neuroprotective properties. Dosing varies according to route of administration, with 25-50 mg per day being a normal dose via ingestion, and up to 1500 mg per day, according to the Florida Department of Health (Rule 64-4.015). We highly recommend opting for high-grade full-spectrum CBD products with independent third-party lab testing to ensure efficacy. All in all, CBD is a great natural dietary supplement, and when used right, can be an excellent therapy for a wide variety of acute and chronic health and wellness issues.

 

 

 

References

(1)          Campos, A. C.; Moreira, F. A.; Gomes, F. V.; del Bel, E. A.; Guimarães, F. S. Multiple Mechanisms Involved in the Large-Spectrum Therapeutic Potential of Cannabidiol in Psychiatric Disorders. Philosophical Transactions of the Royal Society B: Biological Sciences. 2012.


(2)          Blessing, E. M.; Steenkamp, M. M.; Manzanares, J.; Marmar, C. R. Cannabidiol as a Potential Treatment for Anxiety Disorders. Neurotherapeutics. 2015.

(3)          Fernández-Ruiz, J.; Sagredo, O.; Pazos, M. R.; García, C.; Pertwee, R.; Mechoulam, R.; Martínez-Orgado, J. Cannabidiol for Neurodegenerative Disorders: Important New Clinical Applications for This Phytocannabinoid? Br. J. Clin. Pharmacol. 2013.

(4)          Devinsky, O.; Cilio, M. R.; Cross, H.; Fernandez-Ruiz, J.; French, J.; Hill, C.; Katz, R.; Di Marzo, V.; Jutras-Aswad, D.; Notcutt, W. G.; et al. Cannabidiol: Pharmacology and Potential Therapeutic Role in Epilepsy and Other Neuropsychiatric Disorders. Epilepsia 2014.

(5)          Rajesh, M.; Mukhopadhyay, P.; Btkai, S.; Patel, V.; Saito, K.; Matsumoto, S.; Kashiwaya, Y.; Horvth, B.; Mukhopadhyay, B.; Becker, L.; et al. Cannabidiol Attenuates Cardiac Dysfunction, Oxidative Stress, Fibrosis, and Inflammatory and Cell Death Signaling Pathways in Diabetic Cardiomyopathy. J. Am. Coll. Cardiol. 2010.

(6)          Hill, M. N.; Tasker, J. G. Endocannabinoid Signaling, Glucocorticoid-Mediated Negative Feedback, and Regulation of the Hypothalamic-Pituitary-Adrenal Axis. Neuroscience. 2012.

(7)          Grinspoon, L.; Bakalar, J. B. Marihuana as Medicine. JAMA 1995.

(8)          Pollan, M.; Chapela, I.; Gallagher, C.; Unterman, P. Cannabis, Forgetting and the Botany of Desire; 2012.

(9)          Hayakawa, K.; Mishima, K.; Nozako, M.; Ogata, A.; Hazekawa, M.; Liu, A. X.; Fujioka, M.; Abe, K.; Hasebe, N.; Egashira, N.; et al. Repeated Treatment with Cannabidiol but Not Δ9-Tetrahydrocannabinol Has a Neuroprotective Effect without the Development of Tolerance. Neuropharmacology 2007.

(10)        Rock, E. M.; Bolognini, D.; Limebeer, C. L.; Cascio, M. G.; Anavi-Goffer, S.; Fletcher, P. J.; Mechoulam, R.; Pertwee, R. G.; Parker, L. A. Cannabidiol, a Nonpsychotropic Component of Cannabis, Attenuates Vomiting and Nausea-like Behaviour via Indirect Agonism of 5-HT 1A Somatodendritic Autoreceptors in the Dorsal Raphe Nucleus. Br. J. Pharmacol. 2012.

(11)        Nahtigal, I.; Blake, A.; Hand, A.; Florentinus-Mefailoski, A.; Hashemi, H.; Friedberg, J. The Pharmacological Properties of Cannabis. J. Pain Manag. 2016.

(12)        Borges, R. S.; Batista, J.; Viana, R. B.; Baetas, A. C.; Orestes, E.; Andrade, M. A.; Honório, K. M.; Da Silva, A. B. F. Understanding the Molecular Aspects of Tetrahydrocannabinol and Cannabidiol as Antioxidants. Molecules 2013.

(13)        Jansen, A. S. P.; Van Nguyen, X.; Karpitskiy, V.; Mettenleiter, T. C.; Loewy, A. D. Central Command Neurons of the Sympathetic Nervous System: Basis of the Fight-or-Flight Response. Science (80-. ). 1995.

(14)        Hampson, A. J.; Grimaldi, M.; Axelrod, J.; Wink, D. Cannabidiol and (-) 9-Tetrahydrocannabinol Are Neuroprotective Antioxidants. Proc. Natl. Acad. Sci. 1998.

(15)        Campos, A. C.; Fogaça, M. V.; Scarante, F. F.; Joca, S. R. L.; Sales, A. J.; Gomes, F. V.; Sonego, A. B.; Rodrigues, N. S.; Galve-Roperh, I.; Guimarães, F. S. Plastic and Neuroprotective Mechanisms Involved in the Therapeutic Effects of Cannabidiol in Psychiatric Disorders. Frontiers in Pharmacology. 2017.

 

High 4OHE1

4OHE1 is a catechol estrogen formed by aromatic hydroxylation of primary estrogens at either the C-2 or C-4 position.  4OHE1 can be oxidized to catechol estrogen quinones if it is not inactivated by COMT and/or sulfation, glucuronidation, etc. These catechol quinones can react with DNA to produce an excess of estrogen-DNA adducts with subsequent cancer-initiating mutations. This sequence of events is possibly related to uterine fibroids in addition to cancer in the breast, uterus, and prostate.

When a patient is producing too much 4OE1 catechol estrogen, there are 4 primary approaches utilized to decrease the harmful effects and potential increased cancer risk, while still being able to maintain adequate hormone replacement therapy.

  1. Decrease the production of 4OHE1 by directing primary estrogen down alternative pathways.
  2. Increase the production of the safer estrogen metabolite, 4-MeOE1, by supporting the methylation of 4OHE1 in addition to supporting sulfation and glucuronidation.
  3. Protect against the conversion of 4OHE1 estrogens to dangerous quinones that injure DNA.
  4. Support glutathione production, because glutathione can detox dangerous quinones.

Decrease the production of 4OHE1 by directing primary estrogen down alternative pathways.

Although low levels of 4OHE1 are likely OK, it is very important that your liver metabolizes (breaks down) hormones effectively to avoid the production of too much 4OHE1. The liver has the option of taking estrogen down 3 different pathways, only one of which ends in increased 4OHE1. CYP1B1 is the enzyme pathway in the liver that leads to 4OHE1 production.  There are genetic variants that upregulate the CYP1B1 enzyme, predisposing a person to taking estrogen down the 4OHE1 pathway. There are toxins that turn on the CYP1B1 enzyme, subsequently increasing the production of 4OHE1. There are nutrients found in foods and in supportive supplementation that preferentially turn on the alternative pathways that do not result in 4OHE1 production. Supporting liver metabolism of estrogen down more protective pathways is accomplished with a healthy diet, the avoidance of environmental toxins (including xenoestrogens), and supportive supplementation and hormone optimization.

To inhibit the 4OHE1 pathway and/or turn on the alternative pathways particularly the safer CYP-1A1 enzyme pathway that leads to the production of 2OHE1, a safer estrogen metabolite:

  1. Eat a healthy diet
    1. Cruciferous vegetables contain the phytochemical indole-3-carbinol (I3C). In the body, I3C is broken down to 3.3-diindolylmethane – DIM, for short. Cruciferous vegetables include: arugula, broccoli, brussels sprouts, cabbage, cauliflower, collard greens, kale, radishes, rutabaga, turnips and watercress.
    2. Strawberries, blackberries and raspberries (sources of Ellagic acid)
    3. Purple Grapes (a source of Resveratrol)
    4. Green tea (a source of EGCG- epigallocatechin gallate)
    5. Avoidance of Caffeine
    6. Avoidance of simple sugars
    7. Avoidance of excessive omega 6 fatty acids
  2. Avoid environmental toxin exposure
    1. Xenoestrogens, a group of either naturally-occurring or artificially-created compounds in the environment, show hormone-like properties: they are both imperfect, potent estrogens and endocrine disruptors. The more efficacious a Xenoestrogen, the more it disrupts the action of physiologic estrogens. In addition, the liver can only do so much. If the liver is busy metabolizing xenoestrogens from the environment, it is not going to do as well metabolizing endogenous estrogens made by the body. Important xenoestrogens to note include: plastics, pesticides, soy isolates, and products from animals raised with inappropriate hormone exposure.
    2. PAHs – (Polycyclic Aromatic Hydrocarbons). PAHs in air are produced by burning wood and fuel for homes. They are also contained in gasoline and diesel exhaust, soot, cola, and smoke from cigars and cigarettes.
    3. PCBs (Polychlorinated Biphenyls). PCBs belong to a broad family of man-made organic chemicals known as chlorinated hydrocarbons. PCBs were domestically manufactured from 1929 until manufacturing was banned in 1979. They have a range of toxicity. Although no longer commercially produced in the United States, PCBs may be present in products and materials produced before the 1979 PCB ban. Products that may contain PCBs include: transformers and capacitors, electrical equipment, oil used in motors and hydraulic systems, old electrical devices or appliances containing PCB capacitors, fluorescent light ballasts, cable insulation, thermal insulation material (including fiberglass, felt, foam, and cork), adhesives and tapes, oil-based paint, caulking, plastics, carbonless copy paper, & floor finish. PCBs can accumulate in the leaves and above-ground parts of plants and food crops. They are also taken up into the bodies of small organisms and fish. As a result, people who ingest fish may be exposed to PCBs that have bioaccumulated in the fish they are ingesting.
  3. Optimize hormones
    1. Such as Thyroxine, Progesterone, DHEA
    2. Avoidance of birth control pills
  4. Supplementation
    1. EstroPure
    2. Pure Balance
    3. Pure Hormone Support – F
    4. Pure Fish Oil or OmegaAvail Smoothies. Omega -3 found in fish have been shown to promote estrogen using the C-2 pathway. This is particularly true for EPA omega-3 fatty acids.

Increase the production of the safer estrogen metabolite (4-MeOE1) by supporting the methylation of 4OHE1, in addition to supporting sulfation, glucuronidation, and conjugation to glutathione.

If 4OHE1 is overproduced, it is less likely to oxidize to carcinogenic compounds.  That creates DNA adducts if it is neutralized via methylation, sulfation, glucuronidation and/or conjugation to glutathione. Methylation by the enzyme COMT converts the 4OHE1 form of estrogen to 4-MeOE1, a safer form of estrogen. Nutrients to support the COMT enzyme include: Methionine (especially important if low homocysteine), Magnesium, B2, B6, B12, Folate (folinic acid, 5-formyl THF, or 5-methyl THF), TMG (betaine), and choline. Sulfur containing amino acids support sulfation, glucuronidation, and conjugation with glutathione.

  1. Supplementation to consider:
    1. Pure Methylation
    2. Homocysteine Supreme
    3. Magnesium Glycinate, Reacted Magnesium.
    4. Caution with excessive calcium supplementation
    5. Sulfur containing compounds/amino acids like: MSM (Methylsulfonlymethane), NAC (N-Acetyl Cysteine), and Methionine
  2. Avoid factors that slow or inhibit COMT.
    1. Rule out Mercury toxicity as mercury inhibits the COMT activity through inhibition of S-adenosylmethionine (SAM), a coenzyme for COMT.
    2. Plastics inhibit COMT activity
    3. Chronic Stress – the COMT enzyme is involved in the metabolism of neurotransmitters, using up available nutrients for COMT optimization in the liver.

Protect against conversion of 4OHE1 estrogens to dangerous quinones that injure DNA

  1. Avoid trans fats
  2. Avoid heavy metal exposure
  3. Supplementation:
    1. Melatonin
    2. Theanine
    3. Sulphoraphane

Support glutathione production because glutathione can detox dangerous quinones

  1. Diet
    1. Sulfur-rich foods like garlic and onions to provide sulfur containing amino acids
    2. Bioactive Whey Protein, if tolerated – a great source of cysteine
  2. Supplementation to boost glutathione production
    1. N-Acetyl Cysteine
    2. Glutamine
    3. Glycine
    4. Selenium
    5. Pure Energy
  3. Decrease excessive use of glutathione by: avoiding excessive pharmaceuticals, decreasing heavy metal exposure, decreasing cigarette exposure and air pollution, all of which use up available glutathione.
  4. Reactivate glutathione by increasing Vitamin C and Vitamin E.

Julie Kissel, MDSince 1996, Julie Kissel, M.D., has served the greater Cincinnati area by helping thousands of men and women relieve the symptoms of andropause and menopause through a combination of integrative medicine, bioidentical hormone replacement therapy, targeted supplementation, and customized nutritional counseling. She earned her medical degree at the University of Cincinnati and is Board Certified in Integrative Medicine and Family Practice. Dr. Kissel is also fellowship trained in anti-aging and regenerative medicine and an active member of the American Academy for Anti-Aging Medicine.

Total Estrogen and Precision Medicine: Treating Our Patients vs. Treating the Population

Throughout the history of medicine, healthcare trends have evolved toward disease prevention instead of treating disease. Yet, the flood of lifestyle and dietary changes designed to avoid certain diseases seems to be more of a marketing strategy for food distributors, health clubs and supplement companies than realistic and actionable recommendations in practice.  In recent years, a number of studies have discussed the association between genetic mutations (SNPs), estrogen sensitive cancers (breast, uterine and prostate), and estrogen hormone replacement therapies. In these studies, there seemed to be a clear association between orally administered synthetic estrogen and the development of estrogen-sensitive cancer. However, as more and more medical practitioners switched from oral administration of synthetic estrogen to bio-identical creams, patches, gels and pellets, the association between estrogen and breast cancers appeared to decrease. Those prescribing and/or marketing bioidentical hormones made the assumption that breast cancer risk was related to the synthetic make-up in oral administration of estrogen, but although the association to synthetic oral estrogen to cancer is statistically significant, this assumption may be misleading. This article will specifically discuss the pathways of estrogen metabolism, what these pathways represent in clinical practice and how to identify and, subsequently, mitigate the risks associated with developing estrogen-sensitive breast, uterine and prostate cancers in disease prevention.

Estrogen is essential in both men and women for bone health, brain health, cardiovascular health, reproductive health and has even shown positive effects in treating certain cancers. It is clear that maintaining optimal levels of estrogen is very important, because having too much or too little estrogen can present with a myriad of symptoms. Measuring Estrogen before addressing suspected hormone imbalances and monitoring estrogen levels during hormone replacement therapy are crucial in maintaining hormone balance, but the clinical science behind the risks and benefits of Estrogen relating to cancer remained a mystery until estrogen metabolism became more understood. In order to customize therapies for patients while mitigating risks associated with estrogen-sensitive cancers, all primary estrogens (Estrone, Estradiol and Estriol), as well as the downstream estrogen metabolites, must be evaluated.

Most practitioners are accustomed to evaluating serum estradiol by itself when determining if a patient is a candidate for estrogen hormone therapy, but measuring a single estrogen significantly limits practitioners in developing therapies that are precise to each individual patient. As men and women age, aromatase activity takes place at the testosterone precursor, Androstenedione, at a higher rate than the aromatase activity at Testosterone observed in younger populations. The result is a migration toward estrone production over estradiol; so simply measuring estradiol can produce an inaccurate assessment of estrogen effect at the estrogen receptors (ERs).

In addition to assessing Estrone, it is essential to look at the various stages of Estradiol, Estrone and Estrone metabolism collectively. Special attention should be paid to the amount of free hormone that is available to tissues based on the binding affinities of estrone (E1), estradiol (E2), estriol (E3) and 16-alpha-hydroxyestrone at the estrogen receptors.1,2 The Total Estrogen Effect (TEE) in urinary hormone and hormone metabolite testing is calculated based on the presence of estrone, estradiol, estriol, and their relative binding affinities at the estrogen receptors.1,2 Estradiol is considered to be the most estrogenic estrogen and is the prevalent primary estrogen produced by menstruating women. Estradiol has a strong and long-binding affinity at the estrogen receptors and is responsible for most cell proliferation at estrogen-sensitive tissues, such as breast and uterine tissues, in menstruating women.1-6 Based on receptor availability at the tissues, estradiol is converted to estrone and further converted to estriol through the 16-alpha-hydroxyestrone metabolism pathway during Phase I metabolism. Unless a female is pregnant or menopausal, most estrone and estriol is a result of conversion from estradiol. Based on this knowledge, we are able to assume the estrogen effect at the estrogen receptors. The calculation for the TEE assumes certain standard binding affinities at the estrogen receptors. Estriol is the weakest binding primary estrogen at the estrogen receptors and can compete with stronger-binding estrogens.2 Due to its competitive nature and its weaker binding affinity, estriol is considered to be a protective estrogen.1,3,10 Following estriol in binding affinity is estrone (4x more estrogenic than estriol), 16a-hydroxyestrone (9x more estrogenic than estriol), and estradiol (10x more estrogenic than estriol).2,7 These relative values are added together to establish the Total Estrogen Effect at the ERs.

Table 1: Fictitious Example (If a patient has an estriol of 2, an estrone of 2, a 16a-OHE1 of 2, and an estradiol of 2, then the Total Estrogen Effect (TEE) would be 48 based on their relative binding affinities)

Estrogen Fictitious Result Binding-Affinity Multiplier Total
Estriol 2 1 2
Estrone 2 4 8
16a-OHE1** 2 9 18
Estradiol 2 10 20
Total Estrogen Load
48

**Although 16a-OHE1 is a Phase I metabolite, it is included in the calculation due to its ability to contribute to estrogen dominance.

Assessing the amount of estrogen effect at the receptor is the best way to decide if a patient is a candidate for estrogen hormone replacement, but this assessment is only the beginning; assessing Phase I and Phase II metabolism of estrogen is where inflammatory responses and cancer risk are assessed and customized therapies are derived.

As shown in Figure 2, there are three distinct pathways of Phase I metabolism of Estrone, resulting in 2-hydroxyestrone (the most favorable pathway of metabolism), 16-alpha-hydroxyestrone (a result of inflammation) and 4-hydroxyestrone (a carcinogenic pathway). These Phase I pathways are directly impacted by lifestyle and dietary choices.

  • 4-OHE1 is catalyzed predominantly through CYP1B1
  • 2-OHE1 is catalyzed predominantly through CYP1A1
  • 16-a-OHE1 is catalyzed predominantly through CYP3a4

Improvements in lifestyle result in a preference of metabolism down the most favorable 2-hydroxyestrone pathway. 2-hydroxyestrone does not bind to the estrogen receptors. However, COMT activity causes the methylation of 2-hydroxyestrone in Phase II metabolism. That results in stable DNA adducts and can slow estrogen-sensitive cell growth and even reverse DNA damage caused by the 4-OHE1 pathway of Phase I metabolism. 2-methoxyestrone has also been shown to reverse inflammatory responses to estrogen dominance and slow or reverse breast, uterine and prostate cancer growth. When estrogen dominance or certain mutations in the CYP1B1 gene are present, Phase I metabolism increases down the 4-hydroxyestrone pathway. 4-Hydroxyestrones are highly reactive and form 3,4 Quinones that can form unstable DNA adducts, resulting in the creation of carcinogenic mutations. The 4-hydroxyestrone pathway is additionally influenced by environmental toxins, so patients who have CYP1B1 SNPs are especially susceptible to estrogen-sensitive cancers. Because 4-OHE1 is a biomarker of CYP1B1 SNPs, patients with increased 4-OHE1 levels should avoid chemical toxins and improve methylation to drive Phase II detoxification of 4-OHE1. When 4-OHE1 is methylated in Phase II metabolism, the carcinogenic effects of 4-OHE1 are completely neutralized.  Finally, the 16-alpha-hydroxyestrone pathway increases in the presence of inflammation. While most of this inflammation stems from the gut, estrogen dominance and the presence of estrogen-sensitive cancers can increase 16-a-OHE1 during Phase I metabolism as well. The best way to assess 16-a-OHE1 levels is the relative rate of metabolism of 2-OHE1 to 16-a-OHE1 via the 2:16 ratio. When the 2:16 is low, supporting Phase I metabolism and reducing gut inflammation are the primary ways to redirect Phase I metabolism down the 2-OHE1 pathway. Additionally, driving the 16-a-OHE1 pathway through 16-a-OHE1 to Estriol (via 16-hydroxylase activity) is another way to protect the tissues from estrogen dominance through weaker competitive binding of estriol at the ERs. 16-a-OHE1 covalently binds to ERs, resulting in long-standing action at the target tissues. This covalently-binding estrogen metabolite has positive effects in cell proliferation and has even been used to treat certain cancers, but it can cause an existing cancerous tumor or damaged estrogen-sensitive tissue to grow aggressively as well. This unique action of increased 16-a-OHE1 in the presence of inflammation, followed by increase cell proliferation, makes 16-a-OHE1 advantageous in the absence of free-radicals and un-repaired DNA damage. On the other hand, this action makes 16-a-OHE1detrimentally aggressive in the presence of cancer or certain genetic predispositions to increases in 4-OHE1. This is why assessing estrogen metabolism, modulating Phase I metabolism through lifestyle, and supporting Phase II metabolism through methylation and glutathione activity are essential in customizing therapies for patients and optimizing clinical outcomes.

Provided there is sufficient glutathione activity, the removal of DNA-damaging free-radicals is a regular event inside of cells. In the event of DNA mutations, insufficient DNA repair and the initiation of cancerous tissue, these mechanisms of cellular defense are likely compromised significantly. Un-repaired DNA damage is a major cause of cancer initiation. Again, the 2-hydroxy ➝ 2-methyoxyestrone pathway is the most advantageous pathway for repairing DNA damage and reversing the effect of free-radicals, as well as glutathione activity.

A number of nutrients, botanicals and nutrient compounds have been identified as having varying effects on the estrogen-metabolizing and detoxifying pathways. Implementation of many of these compounds through an individualized process affords great potential for those affected by the potentially deleterious effects of aberrant estrogen metabolism.

  • DIM (diindolylmethane) – DIM is used to stimulate 2 hydroxylation (neutral estrogen pathway) via CYP1A1 and reduce expression of 16 hydroxylation (potential harmful estrogen pathway) through inhibiting CYP3a4. There is far more potential therapeutic action to DIM, however. DIM has been shown to reduce DNA hypermethylation of CpG islands (hallmark feature of cancer activity), reduce intestinal inflammation, function to mildly inhibit aromatase, and enhance DNA repair mechanisms.
  • Flax seeds – Flax seeds are a promoter of CYP1A1 and an inhibitor of CYP1B1. Thus, flax seeds are promoters of 2 hydroxylation (neutral estrogen) and inhibitors of 4 hydroxylation (potentially undesirable). Flax also has shown to inhibit CYP3a4 and reduce the excretion of 16OHE1, another potentially-problematic estrogen.
  • Berries – Numerous types of berries (blackberries, raspberries, grapes, blueberries) are a rich source of polyphenolic compounds, including ellagic acid. Ellagic acid is a promoter of glutathione transferase (GSTM), as well as NQO1 (quinone reductase). These 2 enzymes are important in the detoxification of 3,4 semi-quinones. Additionally, ellagic acid has been shown to increase DNA repair genes, as well as reduce DNA adducts that have been formed by carcinogens.
  • Grapefruit & Citrus peel – Are sources of hesperidin. Hesperidin, at high doses, inhibits CYP1B1 and also CYP3a4. Grapefruit is notorious for inhibiting CYP3a4. Citrus peel contains a considerable amount of hesperidin; that is especially true of dried tangerine peel. An assortment of studies done on hesperidin have found an overall increase in blood flow and circulation, reduction in blood pressure, and reduction in symptoms of cell adhesion factors, which may disrupt cancer activities.
  • Calcium D-glucarate – Is a form of calcium that promotes phase 2 glucuronidation. This phase 2 reaction makes molecules more water-soluble. Additionally, it is believed that calcium d-glucarate is a beta glucuronidase inhibitor, which acts to prevent the reabsorption of detoxified estrogens through 2nd pass metabolism.
  • Glutathione promoters and/or cofactors: NAC, lipoic acid, selenium, B-2, B-6, zinci

REFERENCES

  1. Lemon HM. Pathophysiologic considerations in the treatment of menopausal patients with oestrogens; the role of oestriol in the prevention of mammary carcinoma. Acta Endocrinol Suppl (Copenh). 1980;233:17-27.
  2. Blair RM, Fang H, Branham WS, et al. The estrogen receptor relative binding affinities of 188 natural and xenochemicals: structural diversity of ligands. Toxicol Sci. 2000;54(1):138-153.
  3. Sepkovic DW, Bradlow HL. Estrogen hydroxylation—the good and the bad. Ann N Y Acad Sci. 2009;1155(1):57-67. doi:10.1111/j.1749-6632.2008.03675.x.
  4. Barba M, Yang L, Schünemann HJ, et al. Urinary estrogen metabolites and prostate cancer: a case-control study and meta-analysis. J Exp Clin Cancer Res. 2009;28:135. doi:10.1186/1756-9966-28-135.
  5. Dondi D, Piccolella M, Biserni A, et al. Estrogen receptor beta and the progression of prostate cancer: role of 5alpha-androstane-3beta,17beta-diol. Endocr Relat Cancer. 2010;17(3):731-742. doi:10.1677/ERC-10-0032.
  6. Oliveira AG, Coelho PH, Guedes FD, Mahecha GA, Hess RA, Oliveira CA. 5alpha-androstane-3beta,17beta-diol (3beta-diol), an estrogenic metabolite of 5alpha-dihydrotestosterone, is a potent modulator of estrogen receptor ERbeta expression in the ventral prostrate of adult. Steroids. 2007;72(14):914-922. doi:10.1016/j.steroids.2007.08.001.
  7. Serafimova R, Todorov M, Nedelcheva D, et al. QSAR and mechanistic interpretation of estrogen receptor binding. SAR QSAR Environ Res. 2007;18(3-4):389-421. doi:10.1080/10629360601053992.
  8. Fabres C, Zegers-Hochschild F, Altieri E, Llados C. Validation of the dual analyte assay of the oestrone:pregnanediol ratio in monitoring ovarian function. Hum Reprod. 1993;8(2):208-210.
  9. Collins WP, Collins PO, Kilpatrick MJ, Manning PA, Pike JM, Tyler JP. The concentrations of urinary oestrone-3-glucuronide, LH and pregnanediol-3alpha-glucuronide as indices of ovarian function. Acta Endocrinol (Copenh). 1979;90(2):336-348.
  10. Bratoeff E, Segura T, Recillas S, et al. Aromatic esters of progesterone as 5alpha-reductase and prostate growth inhibitors. J Enzyme Inhib Med Chem. 2009;24(3):655-662. doi:10.1080/14756360802323720.
  11. Bradlow HL, Telang NT, Sepkovic DW, Osborne MP. 2-hydroxyestrone: the ‘good’ estrogen. J Endocrinol. 1996;150(Suppl):S259-265.
  12. Kabat GC, O’Leary ES, Gammon MD, et al. Estrogen metabolism and breast cancer. Epidemiology. 2006;17(1):80-88.
  13. Robinson JA, Waters KM, Turner RT, Spelsberg TC. Direct action of naturally occurring estrogen metabolites on human osteoblastic cells. J Bone Miner Res. 2000;15(3):499-506. doi:10.1359/jbmr.2000.15.3.499.
  14. Lotinun S, Westerlind KC, Kennedy AM, Turner RT. Comparative effects of long-term continuous release of 16 alpha-hydroxyestrone and 17 beta-estradiol on bone, uterus, and serum cholesterol in ovariectomized adult rats. Bone. 2003;33(1):124-131.
  15. Napoli N, Faccio R, Shrestha V, Bucchieri S, Rini GB, Armamento-Villareal R. Estrogen metabolism modulates bone density in men. Calcif Tissue Int. 2007;80(4):227-232. doi:10.1007/s00223-007-9014-4.
  16. Bradlow HL, Zeligs MA. Diindolylmethane (DIM) spontaneously forms from indole-3-carbinol (I3C) during cell culture experiments. In Vivo. 2010;24(4):387-391.
  17. Lord RS, Bongiovanni B, Bralley JA. Estrogen metabolism and the diet-cancer connection: rationale for assessing the ratio of urinary hydroxylated estrogen metabolites. Altern Med Rev. 2002;7(2):112-129.
  18. Higdon JV, Delage B, Williams DE, Dashwood RH. Cruciferous vegetables and human cancer risk: epidemiologic evidence and mechanistic basis. Pharmacol Res. 2007;55(3):224-236. doi:10.1016/j.phrs.2007.01.009.
  19. Fowke JH, Longcope C, Hebert JR. Brassica vegetable consumption shifts estrogen metabolism in healthy postmenopausal women. Cancer Epidemiol Biomarkers Prev. 2000;9(8):773-779.
  20. Xu X, Duncan AM, Wangen KE, Kurzer MS. Soy consumption alters endogenous estrogen metabolism in postmenopausal women. Cancer Epidemiol Biomarkers Prev. 2000;9(8):781-786.
  21. Sturgeon SR, Volpe SL, Puleo E, et al. Effect of flaxseed consumption on urinary levels of estrogen metabolites in postmenopausal women. Nutr Cancer. 2010;62(2):175-180. doi:10.1080/01635580903305342.
  22. Bentz AT, Schneider CM, Westerlind KC. The relationship between physical activity and 2-hydroxyestrone, 16alpha-hydroxyestrone, and the 2/16 ratio in premenopausal women (United States). Cancer Causes Control. 2005;16(4):455-461. doi:10.1007/s10552-004-6256-6.
  23. Wright JV. Bio-identical steroid hormone replacement: selected observations from 23 years of clinical and laboratory practice. Ann N Y Acad Sci. 2005;1057:506-524. doi:10.1196/annals.1356.039.
  24. Zahid M, Kohli E, Saeed M, Rogan E, Cavalieri E. The greater reactivity of estradiol-3,4-quinone vs estradiol-2,3-quinone with DNA in the formation of depurinating adducts: implications for tumor-initiating activity. Chem Res Toxicol. 2006;19(1):164-172. doi:10.1021/tx050229y.
  25. Cavalieri EL, Stack DE, Devanesan PD, et al. Molecular origin of cancer: catechol estrogen-3,4-quinones as endogenous tumor initiators. Proc Natl Acad Sci U S A. 1997;94(20):10937-10942.
  26. Brooks JD, Ward WE, Lewis JE, et al. Supplementation with flaxseed alters estrogen metabolism in postmenopausal women to a greater extent than does supplementation with an equal amount of soy. Am J Clin Nutr. 2004;79(2):318-325. doi:10.1093/ajcn/79.2.318.
  27. Craig Cooney, PhD; Methyl Magic. Andrews McMeel Publishing; Kansas City, MO; 1999.
  28. Joseph Mercola, DO. Vitamin B12: Essential for Vigorous Good Health.
  29. John V. Dommisse, MD. Subtle vitamin B12 deficiency and psychiatry: A largely unnoticed but devastating relationship? Medical Hypotheses; 1991.
  30. K.L. Stone et al. Low serum vitamin B12 levels are associated with increased hip bone loss in older women: A prospective study. Journal of Clinical Endocrinology & Metabolism; 2004.
  31. J.B.J. van Meurs, PhD, et al. Homocysteine levels and the risk of osteoporotic fracture. New England Journal of Medicine; 2004.
  32. Martin Lajous et al. Folate, Vitamin B6, and Vitamin B12 Intake and the Risk of Breast Cancer Among Mexican Women. Cancer Epidemiol Biomarkers Prev; 2006.