Vitamin D: To Supplement or Not?

It’s been brewing and it’s finally here! This post is all about Vitamin D, “the sunshine vitamin.” What most people don’t know is that Vitamin D is actually a hormone!

That said, to avoid any confusion, I’d like to preface by saying I’ll be referring to Vitamin D as “Hormone-D” throughout this blog post.

Hormone-D has many benefits, but understanding what it does and how can be very confusing. I’m hoping to clarify this!

A heads up, there are a few of you who got super excited about my magnesium post and immediately bought supplements before I posted about the best kinds. I encourage you to please hold off until you’ve finished reading this posts before you decide if Hormone-D is right for you. You might be surprised at what I’m about to tell you.

Read on to learn more about this amazing hormone.

What is Hormone-D?

You’ve waited long enough...let’s get into it!

Hormone-D is an essential, fat-soluble nutrient that we obtain primarily from the ultraviolet rays of the sun and through some foods. Some sources say we should get 80% from the sun and 20% from our food. Others say we can get 100% of our Hormone-D from just 15-minutes of sun exposure every day.

There are many versions of Hormone-D. There’s Ergocalciferol, Vitamin D2, which is present in plant foods and Cholecalciferol, Vitamin D3, present in animal foods. Animal food sources (D3) are the most easily absorbed and used by the body. We also get Vitamin D3 from the sun.

The inactive or storage form of Hormone-D is called Calcidiol. When Hormone-D is converted into its active form, D3 (Calcitriol), it's best known for helping us absorb Calcium from our digestive system into the blood. With Hormone-D, we can absorb 30-40% of our dietary calcium. Without it, we can only absorb around 10-15%. This is what makes Hormone-D so vital for healthy teeth and bones.

Aside from its relationship with Calcium, Hormone-D is also an important modulator of cell growth, neurotransmitter and immune system function, inflammation, and gene coding.

Like many things in the human body, Hormone-D can be a little bit complicated. Interested in learning more about how Hormone-D works? Keeping reading!

How Does Hormone-D Work?

Just like plants, humans have a very intimate relationship with the sun. Not only does it help set our biological and hormonal clocks (Circadian Rhythm, Cortisol Awakening Response, etc), it helps us absorb and regulate the mineral status of our bodies.

When your skin is exposed to sunlight, two things are produced: Cholesterol Sulfate and Vitamin D Sulfate. This sulfated Hormone-D is transported in the blood to the liver via Vitamin-D-Binding Protein (VDBP) where it’s converted to Calcidiol, the storage form of D. Calcidiol is then transported to the kidneys, again via VDBP, where it’s converted to the active form of Hormone-D, Calcitriol (D3). D3 is transported, again via VDBP, to target organs including the kidneys themselves, the pancreas, the bones, and the immune system. These organs all have Vitamin D Receptors (VDRs), which D3 can bind to, allowing for the absorption and regulation of Calcium.

Aside from this sun-skin transaction, the Parathyroid (PT) also has a lot to do with the mineral status of our blood, which needs to be kept at a pH between 7.35 and 7.45. Phosphorus (acidic) and Calcium (basic) are antagonists of pH balance. If the blood becomes too acidic, which is more common than not (from alcohol consumption, imbalanced blood sugar, overconsumption of muscle meat, etc), the PT will release Parathyroid Hormone (PTH), whose main goal is to help neutralize the pH of the blood. It does this by promoting the formation of D3 in the kidneys to boost Calcium absorption from food and increasing the breakdown of bone for the release of Calcium into the bloodstream.

Hormone-D seems pretty important, right? You might be wondering how it’s possible that 1 in 4 Americans are deficient. Read on to learn why.

Why Are We Deficient?

42% of Americans are deficient in Hormone-D. You would think that with high cholesterol being rampant we would be at 100%, right? Nope! There are so many reasons you could be deficient - check them out below…some of them may surprise you!

• Mg DEFICIENCY. Magnesium is needed for almost every step in Hormone-D conversion yet, in my last series, we learned that 75% of America may be Mg deficient. The body will purposefully lower storage D levels if there is not enough Mg to convert storage D into active D or too much Calcium (Mg antagonist). Why? Because your body is smart and it doesn’t want to calcify you. This strong relationship has experts saying that Mg status alone can determine your Hormone-D status.

• LOW-FAT OR PUFA-LADEN DIETS. Low-fat diets, as well as high unsaturated-fat diets, contain no Retinol (Vitamin A). Retinol is essential for activating the Vitamin D Receptor (VDR) and its immune functions. No Saturated Animal Fat = No Retinol = No Hormone-D.

• LACK OF SUNLIGHT. We humans are terrified of the sun giving us cancer so we stay indoors and slather ourselves in SPF on the rare occasion we do go outside. It’s been hypothesized that what’s really driving cancer is the oxidation of our stored PUFAs and their combination with heavy metals as well...more on that another time. But guess what? Sun exposure allows us to produce Cholesterol Sulfate, which is essential for optimal heart, brain, and red blood cell function. When we’re deficient, our body compensates by repurposing damaged LDL (“Bad”) Cholesterol, turning it into plaque, and waiting for a supply of Sulfate so it can make the conversion to Cholesterol Sulfate. Unfortunately and ironically, this noble plaque increases your risk of cardiovascular disease.

• ALUMINUM (Al). Sunscreens not only block the sun, they contain aluminum, which disrupts the pathways that create Sulfate. Not to mention, this is one of the heavy metals whose oxidation and combination with PUFA may cause cancer.

• GLYPHOSATE. Also known as Roundup, Glyphosate is an herbicide designed to kill weeds and grasses. 250 million pounds are sprayed on American crops every year. It’s in - not on - our fruits and vegetables, grains, legumes, herbs and spices, and seed oils, as well as our parks, forests, sports fields, lawns, and more. Not only has independent research found that it increases our cancer risk by 41.7%, it chelates Zinc, which is required to activate Hormone-D. It also disrupts Cytochrome P450 Enzymes, which are responsible for activating Hormone-D in the liver and kidneys, as well as the enzyme called eNOS, responsible for making Cholesterol Sulfate. Although organic isn’t perfect, Glyphosate is one of the many reasons I emphasize it.

• STATINS. 2 out of the top 10 prescribed drugs in the US are Statins. They function to reduce cholesterol production. Less cholesterol = less raw materials to make hormones, including Hormone-D.

• LIVER AND KIDNEY FUNCTION. 15% of the American population has Chronic Kidney Disease and Chronic Liver Disease and Cirrhosis is the 12th most leading cause of death. We need a healthy liver and kidneys to synthesize and use Hormone-D.

• INFLAMMATION. Many drivers of deficiency are driven by inflammation, which you’ve learned are closely tied to Mg deficiency. During times of inflammation, the body actually naturally lowers storage Hormone-D produces more active Hormone-D (D3 aka 1,25(OH)2 D3) to boost the antimicrobial properties of the immune system. So then, why do doctors panic when they see “Low Vitamin D” on a blood test? That’s because they usually only test for the storage form of Hormone-D (25(OH)D). It’s been said that low storage Hormone-D is a consequence or chronic inflammation rather than the cause. It seems we’re looking at this the wrong way.

• MELANIN. This is not a driver, but something us folks with beautiful, darker toned skin need to be aware of. Melanin is the brown-black pigment in eyes, hair and skin. The darker our skin, the more sun exposure you need to get sufficient Hormone-D.

What’s the common denominator here? We’ve got a lot of things backwards, as usual! Read on to hear about some of the signs, symptoms, and implications of Hormone-D deficiency.

Signs of Hormone-D Deficiency

In the last post you read about the many drivers of our Hormone-D deficiency. So, what are the signs you might be lacking?

An easy one is if you live in a sunny area, but your D levels are abysmal. Other more serious signs:

• Rickets and myopia

• Osteoporosis and other skeletal diseases

• Bone and back pain

• Muscle pain

• Cancer, such as colon, prostate, and breast cancers

• Cardiovascular disease

• High blood pressure

• Infections

• Impaired wound healing

• Immune and autoimmune system disorders

• Infections

• Hair loss

• Fatigue

• IBS

• MS

• Depression and other

• Cognitive disorders

• Diabetes

• Obesity

• Mortality

Because Hormone-D is so closely tied to our immune system, skeletal health, and cardiovascular health, this list spans a wide range. Taking a supplement seems like a no-brainer, right? Not so fast...

Should You Supplement?

It’s very tempting to want to supplement something that’s so vital to your overall function as a human being. In the case of Hormone-D, however, it’s very important to understand the nuances between supplementation and the impact a synthetic version of this hormone can have. Here are some potential implications and drawbacks:

• The only thing that can create Vitamin-D Sulfate is sunlight. This unique sulfation is what makes the hormone water-soluble and allows it to travel freely within the bloodstream. This is the form of Hormone-D that experts believe actually protects us from cancer and cardiovascular disease.

• Hormone-D supplements lower Retinol (Vitamin A) levels in the liver and the blood. Without Retinol, we can’t activate the Vitamin D Receptor (VDR) and important Hormone-D functions like gene coding will be inhibited. Retinol is also critical to create energy (ATP), amongst other important functions. Inability to create energy = stress = disease.

• Because of their impact on Retinol, Hormone-D supplements can also cause the illusion of Anemia. Without Retinol, Hydrogen Peroxide (H2O2), a Reactive Oxygen Species and waste product of inflammation (hello!), is left unchecked. The body senses H2O2 as a threat and will hide Iron inside tissues to keep them from interacting with each other because H2O2 + Iron = rust = the start of many diseases. This lowers your blood levels of Iron, making it “look” like you have Anemia. If Iron does get to interact with H2O2, it creates what’s called the Hydroxyl Radical (OH*), one of the most destructive chemicals in the human body. OH* is said to be the source agent for MTHFR...and even gray hair. More on that another time, but the takeaway here is if you’re taking D supplements and have been told you’re anemic, you may want to rethink your supplementation.

• We need Vitamin K to get Calcium into the bones. We not only need to get enough through our diet and production in our gut, it must be Carboxylated and Phosphorylated to work. We need energy to activate K and as you’ve now seen, synthetic Hormone-D makes it really hard for us to create energy.

• Supplements also drain our levels of Magnesium, which is required for almost every Hormone-D pathway and other hormones involved in Calcium absorption (Calcitonin and PTH). Calcium and Magnesium compete for absorption. Remember, Magnesium is the Yin to Calcium’s Yang. If there is not enough Magnesium, cellular ion channels are left wide open for Calcium and Sodium to flood in. Because of this energy (ATP) cannot be created and calcification can occur. Once again, inability to create energy = stress = disease.

• Hormone-D supplements deplete our cells of Potassium (Renal Potassium Wasting). Potassium (K) is a valuable electrolyte that regulates the amount of water inside cells. Without it, cells are vulnerable to Calcium, Sodium, and Iron coming into the cell in an uncontrolled manner. This is a chain reaction that can lead to things like calcification, renal stress, and more. Unmanaged Calcium and Iron = inability to create energy = stress = disease.

• There’s no clinical benefit to having storage Hormone-D above 21 ng/dL. Both healthy and sick people can have low storage D. It’s sick people that have high active Hormone-D, which should really be a marker for inflammation caused by something else (Mg deficiency, anyone?). Conventional medicine doesn't usually test for this, so it will likely remain a missing piece of your puzzle unless you advocate for yourself.

• Synthetic Hormone-D + Calcium supplementation can actually increase your risk for cardiovascular disease. High Hormone-D supplementation is now thought to be linked to our increasing mortality rates and it may cause renal impairment, hypercalcemia, or vascular calcification. Hormone-D has not been shown to lower cancer risk, unlike many people believe. It’s also been shown to increase the risk of falls in the elderly.

• Only sunshine can activate the POMC gene, which helps create melanin, which determines skin color. POMC also enhances endorphins, which make us happy, and leptin, which regulates hunger.

Make up your mind yet?

How Much D Do You Need?

Yes, we’re still talking about Hormone-D here! So how much D do you actually need every day? And if you’ve decided to take a supplement, which kind should you look for?

Daily recommendations for Hormone-D range from 200-800 IUs, but it’s possible that ideal ranges are higher.
I’m a proponent of sun over supplements, so I try to get 15-minutes of direct sunlight without sunscreen and exposing as much skin as possible (your face will not be enough) between 10 AM and 3 PM or when your shadow is shorter than your body height.

30-minutes of sunlight (while wearing a swimsuit) can provide the following Hormone-D levels:

• Most caucasians: 50,000 IUs

• Olive/tan complexions: 20,000-30,000 IUs

• Dark complexions: 8,000-10,000 IUs

Live somewhere that has minimal sunlight for most of the year? I would consider investing in a Vitamin D lamp or making your own. Most of them you just need to stand in front of for 5-minutes.

If you’re still considering supplementing Hormone-D, it’s important to remember the difference between D2 (Ergocalciferol) and D3 (Cholecalciferol). D2 is derived from plants - plants do not have cholesterol so D3 is the more desirable form as it can actually be converted into the active form (Calcitriol). Additionally,  it shouldn’t be taken at night, as it can interfere with Melatonin production.

Next to direct sunlight, food is my next favorite source of Hormone-D. Keep reading to learn about the best food sources!

Best D Food Sources

In addition to direct sunlight, food is a great way to get Hormone-D, especially during times of little sunlight like the winter. The following foods provide a decent source of Hormone-D:

• Pastured egg yolks

• Grass-fed liver

• Grass-fed butter

• Goat’s milk

• Grass-fed whole milk and whole milk dairy products

• Wild-caught oily fish like mackerel, salmon, sardines, herring

• Wild-caught tuna

• High-quality cod liver oil

Beware of fortified foods, as these often contain synthetic D2 and can be very harmful. Foods commonly fortified with synthetic Vitamin D include:

• Milk

• Soy milk

• Orange juice

• Cereals

• Oatmeals

Other things to think about:

• A few posts back, I talked about Glyphosate and how it can impair Hormone-D function. I’ll make another plea again here to buy organic whenever possible, especially the Dirty Dozen.

• Make sure to get real Vitamin A in your diet so that your body can activate VDRs. Beta Carotene is NOT a replacement for Retinol - get those animal fats in!

• Remember, Magnesium is needed for almost all steps of Hormone-D conversion. Make sure you're getting adequate amounts, especially if you choose to supplement.

That’s all I’ve got folks! This was a long post, so thanks for hanging in there. Hopefully this will help you make an informed decision on whether or not you’d like to supplement Hormone-D for yourself. Make sure to follow me on @innatefunctionalnutrition to get the latest updates.

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This is not medical advice. Always consult your healthcare professional before pursuing any changes to your personal healthcare regime.

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References

Amer, M. Qayyum, R. Relationship between 25-Hydroxyvitamin D and All-cause and Cardiovascular Disease Mortality. Retrieved from: https://www.amjmed.com/article/S0002-9343(13)00084-3/pdf.

Anumanthan, G., Gupta, S., Fink, M.K., Hasemann, N.P., Bowles, D.K., McDaniel, L.M., Muhammed, M., Mohan, R.R. (2018). KCa3.1 ion channel: A novel therapeutic target for corneal fibrosis. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/29554088.

Belluz, J. (2019). Millions of Americans take vitamin D. Most should just stop. Retrieved from: https://www.vox.com/2018/10/4/17933880/vitamin-d-health-sun-diet.

Bolt, M.J., Lui, W., Qiao, G. Kong, J. Zheng, W. Krausz, T. Cs-Szabo, G. Sitrin, M.D., Li, Y.C. (2004). Critical role of vitamin D in sulfate homeostasis: regulation of the sodium-sulfate cotransporter by 1,25-dihydroxyvitamin D3. Retrieved from: https://journals.physiology.org/doi/full/10.1152/ajpendo.00151.2004.

Chandler, S. (2018). Does Milk Really Contain Vitamin D?. Retrieved from: https://healthyeating.sfgate.com/milk-really-contain-vitamin-d-5415.html.

Cheng, C.J., Kuo, E., Huang, C.L. (2013). Extracellular Potassium Homeostasis: Insights from Hypokalemic Periodic Paralysis. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4131448/.

Cherry, K. (2020). How the Circadian Rhythms Act as the Body’s Biological Clock. Retrieved from: https://www.verywellhealth.com/circadian-rhythms-the-bodys-clock-2795928.

Cleveland Clinic. (2019). Vitamin D Deficiency. Retrieved from: https://my.clevelandclinic.org/health/articles/15050-vitamin-d--vitamin-d-deficiency.

Dean, C. (2012). The Calcium Wars: Magnesium deficiency causes heart disease. Retrieved from: https://www.naturalnews.com/038286_magnesium_deficiency_heart_disease.html.

Deering, Kate. (2013). What’s up with Vitamin D? Retrieved from: https://katedeering.com/2013/01/what-is-up-with-vitamin-d/.

Deng, X. Song, Y. Manson, J.E., Signorello, L.B., Zhang, S.M., Shrubsole, M.J., Ness, R.M., Seidner, D.L., Dai, Qi. (2013). Magnesium, vitamin D status and mortality: results from US National Health and Nutrition Examination Survey (NHANES) 2001 to 2006 and NHANES III. Retrieved from: https://bmcmedicine.biomedcentral.com/articles/10.1186/1741-7015-11-187.

Duffy, J.F., Czeisler, C.A. (2009). Effect of Light on Human Circadian Physiology. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717723/.

Durup, D. Jorgensen, H.L., Christensen, J., Schwartz, P. Heegaard, A.M., Lind, B.(2012). A reverse J-shaped association of all-cause mortality with serum 25-hydroxyvitamin D in general practice: the CopD study. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/22573406.

Egles, M.J. (2013). The Calcium to Magnesium Ratio- Effect on Mortality. Retrieved from: https://www.naturalhealthresearch.org/calcium-magnesium-mortality/.

Esposito, L. (2018). How Much Time in the Sun Do You Need for Vitamin D?. Retrieved from: https://health.usnews.com/wellness/articles/2018-07-18/how-much-time-in-the-sun-do-you-need-for-vitamin-d.

Fallon, S. (2001). Nourishing Traditions. Brandywine, MD: NewTrends Publishing.

Faloon, W. (2010). Startling Findings About Vitamin D Levels in Life Extension® Members. Retrieved from: https://www.lifeextension.com/magazine/2010/1/startling-findings-about-vitamin-d-levels-in-life-extension-members.

Ferris, T.F., Levitin, H., Phillips, E.T., Epstein, F.H. (1962). RENAL POTASSIUM-WASTING INDUCED BY VITAMIN D. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC291035/.

Galior, K., Grebe, S., Ravinder, S. (2018). Development of Vitamin D Toxicity from Overcorrection of Vitamin D Deficiency: A Review of Case Reports. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115827/.

Harbolics, B.K. Vitamin D Deficiency. Retrieved from: https://www.medicinenet.com/vitamin_d_deficiency/article.htm.

Harvard Health. (2019). Vitamin D and your health: Breaking old rules, raising new hopes. Retrieved from: https://www.health.harvard.edu/staying-healthy/vitamin-d-and-your-health-breaking-old-rules-raising-new-hopes.

Haas, E. M. Levin, B. (2006). Staying Healthy with Nutrition. New York, NY: Ten Speed Press.

Hatena Blog. (2016). DR/RXR and TCF4/β-Catenin Cistromes in Colonic Constitutive activation of the WNT pathway through mutation of the adenomatous polyposis coli complex. Retrieved from: http://soft-ave28.hatenablog.com/entry/vdrrxr-activation-pathway.

Holland, K. (2018). What Are the 12 Leading Causes of Death in the United States? Retrieved from: https://www.healthline.com/health/leading-causes-of-death.

Huang, W. (2015). High Dose Vitamin D Supplementation May Lead to Increased Risk of Falls. Retrieved from: https://www.mdedge.com/jcomjournal/article/146429/geriatrics/high-dose-vitamin-d-supplementation-may-lead-increased-risk.

Jones, T. (2019). Healthy Foods That Are High in Vitamin D. Retrieved from: https://www.healthline.com/nutrition/9-foods-high-in-vitamin-d#1.

Krane, S.M. (1990). 1,25-Dihydroxyvitamin D3 increases the toxicity of hydrogen peroxide: the role of calcium and heat shock. Retrieved from: https://www.ncbi.nlm.nih.gov/m/pubmed/2226658/.

Kresser, C. (2019). Vitamin D: More Is Not Better. Retrieved from: https://chriskresser.com/vitamin-d-more-is-not-better/.

Lappe, K. Watson, P. Travers-Gustafson, D., Recker, R., Garland, C., Gorham, E., Baggerly, K., McDonnell, S.L. Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/28350929.

Legg, T.J. (2018). What Are the Benefits of Sunlight?. Retrieved from: https://www.healthline.com/health/depression/benefits-sunlight.

Lehman, K., Monford, J.R., Horita, H., Ostriker, A.C., Weiser-Evans, M.C., Nemenoff, R.A., Furgeson, S.B. (2014). Activation of the retinoid X receptor modulates angiotensin II-induced smooth muscle gene expression and inflammation in vascular smooth muscle cells. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/25169989.

Mangin, M., Sinha, R., Fincher, K. (2014). Inflammation and vitamin D: the infection connection. Retrieved from: https://link.springer.com/article/10.1007/s00011-014-0755-z.

Masterjohn, C. (2009). Tufts University Confirms That Vitamin A Protects Against Vitamin D Toxicity by Curbing Excess Production of Vitamin K-Dependent Proteins. Retrieved from: https://chrismasterjohnphd.com/blog/2009/04/07/tufts-university-confirms-that-vitamin.

Mawson, A.R. (2012). Role of Fat-Soluble Vitamins A and D in the Pathogenesis of Influenza: A New Perspective. Retrieved from: https://www.hindawi.com/journals/isrn/2013/246737/.

Mead, N.M. (2008). Benefits of Sunlight: A Bright Spot for Human Health. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2290997/pdf/ehp0116-a00160.pdf.

Mercola, J. (2011). Could THIS Be the Hidden Factor Behind Obesity, Heart Disease, and Chronic Fatigue? Retrieved from: https://articles.mercola.com/sites/articles/archive/2011/09/17/stephanie-seneff-on-sulfur.aspx

Mercola, J. (2014). How Sun Exposure Improves Your Health and How Glyphosate Disrupts It. Retrieved from: https://articles.mercola.com/sites/articles/archive/2014/10/19/cholesterol-sulfate.aspx.

Michel, M.C., Brunner, H.R., Foster, C., Huo, Y. (2016). Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease.Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/27130806.

Munoz-Durango, N., Vecchiola, A., Gonzalez-Gomez, L.M., Simon, F., Riedel, C.A., Fardella, C.E., Kalergis, A.M. (2015).Modulation of Immunity and Inflammation by the Mineralocorticoid Receptor and Aldosterone. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4581510/.

Mora, J.R., Iwata, M., von Andrian, U.H. (2008). Vitamin effects on the immune system: vitamins A and D take centre stage. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/19172691.

National Institutes of Health. (2019). Vitamin D. Retrieved from: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/.

National Kidney Foundation. Kidney Disease: The Basics. Retrieved from: https://www.kidney.org/news/newsroom/factsheets/KidneyDiseaseBasics.

Ogbru, O. Top 10 Prescribed Drugs in the US. Retrieved from: https://www.medicinenet.com/top_drugs_prescribed_in_the_us/views.htm.

Pickart, L. (2018). Skin Regenerative and Anti-Cancer Actions of Copper Peptides. Retrieved from: https://www.mdpi.com/2079-9284/5/2/29/htm. 

Raman, R. (2017). What Does Potassium Do for Your Body? A Detailed Review. Retrieved from: https://www.healthline.com/nutrition/what-does-potassium-do.

Raman, R. (2017). What Vitamin D Dosage is Best? Retrieved from: https://www.healthline.com/nutrition/vitamin-d-dosage.

Raman, R. (2018). How to Safely Get Vitamin D from Sunlight. Retrieved from: https://www.healthline.com/nutrition/vitamin-d-from-sun.

Robbins, M. (2013). The Vitamin-D controversy… Retrieved from: https://therootcauseprotocol.com/the-vitamin-d-controversy/

Robbins, M. (2014). Testing is Key to Hormone-D!. Retrieved from: https://therootcauseprotocol.com/testing-is-key-to-hormone-d/.

Robbins, M. (2016). Why Vitamin D and iron is not a good idea! Retrieved from: https://therootcauseprotocol.com/mag-pie-alert-38-toxicity-of-iron/.

Sampson, S. (2018). How to get the most vitamin D from the sun. Retrieved from: https://www.medicalnewstoday.com/articles/326167.

Samsel, A. Seneff, S. (2013, Dec). Glyphosate, pathways to modern diseases II: Celiac sprue and gluten intolerance. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945755/.

Scragg, R. Stewart, A.W., Waayer, D. (2017). Effect of Monthly High-Dose Vitamin D Supplementation on Cardiovascular Disease in the Vitamin D Assessment Study: A Randomized Clinical Trial. Retrieved from: https://jamanetwork.com/journals/jamacardiology/article-abstract/2615260.

Steptoe, A. Serwinski, B. (2016). Cortisol Awakening Response. Retrieved from: https://www.sciencedirect.com/topics/neuroscience/cortisol-awakening-response.

Spritzler, F. (2018). 8 Signs and Symptoms of Vitamin D Deficiency. Retrieved from: https://www.healthline.com/nutrition/vitamin-d-deficiency-symptoms.

Taylor, R.L. Poultry Science. Retrieved from: https://www.journals.elsevier.com/poultry-science.

University of Copenhagen - The Faculty of Health and Medical Sciences. (2015). High levels of vitamin D is suspected of increasing mortality rates. Retrieved from: https://www.sciencedaily.com/releases/2015/03/150310105222.htm.

USGS. (2015). Estimated Annual Agricultural Pesticide Use. Retrieved from: https://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2016&map=GLYPHOSATE&hilo=L.

Wang, Y. Zhu, J. DeLuca, H.F. (2012). Where is the vitamin D receptor? Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/22503810.

Weitsman, G.E., Koren, R., Zuck, E., Rotem, C., Liberman, U.A., Ravid, A. Vitamin D sensitizes breast cancer cells to the action of H2O2: mitochondria as a convergence point in the death pathway. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/15964518.+

Wheeler, S. (2018). 42% Percent of Americans Are Vitamin D Deficient. Are You Among Them?. Retrieved from: https://www.cantonmercy.org/healthchat/42-percent-of-americans-are-vitamin-d-deficient/.

Wulff, H. Castle, N.A. (2010). Therapeutic potential of KCa3.1 blockers: an overview of recent advances, and promising trends. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3347644/.

Yamamoto, Y. Yancey, P.G., Zuo, Y., Ma, L.J., Kaseda, R., Fogo, A.B., Ichikawa, I., Linton, M.F., Fazio, S., Kon, V. Macrophage polarization by angiotensin II-type 1 receptor aggravates renal injury-acceleration of atherosclerosis. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/21979434.

Younossi, Z.M., Stepanova, M., Younossi, Y. Golabi, P., Mishra, A., Rafiq, N., Henry, L. (2019). Epidemiology of chronic liver diseases in the USA in the past three decades. Retrieved from: https://gut.bmj.com/content/69/3/564.

Zhang, L. Rana, L. Shaffer, RM. Taioli, E. Sheppard, L. (2019, Sep). Exposure to glyphosate-based herbicides and risk for non-Hodgkin lymphoma: A meta-analysis and supporting evidence. Retrieved from: https://www.sciencedirect.com/science/article/pii/S1383574218300887.

Zhong, M. Kawaguchi, R., Kassai, M., Sun, H. (2012). Retina, Retinol, Retinal and the Natural History of Vitamin A as a Light Sensor. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3546623/#!po=0.515464.