Vitamin D: More Is Not Better

by Chris Kresser (web)

Have you been told you need more vitamin D? Healthcare practitioners are increasingly aware of the risks of low vitamin D levels, but many are not aware that high levels of vitamin D can have toxic effects. Read on to learn the risks of over-supplementation, what factors determine your optimal vitamin D level, and the many reasons to get sunlight exposure beyond just vitamin D.

Vitamin D is critical for health. Virtually every cell in the body has a vitamin D receptor, which, when bound to vitamin D, can influence the expression of more than 200 genes (1, 2). Vitamin D promotes calcium absorption in the intestine and maintains calcium and phosphate levels in the blood, protecting against osteoporosis, rickets, and bone fracture (3, 4). It also regulates immune function, cell growth, and neuromuscular function (5, 6).

With the many roles that vitamin D plays in the body, deficiency of this fat-soluble vitamin is a real cause for concern. Vitamin D deficiency has been found to increase the risk of heart attack, cancer, diabetes, asthma, and autoimmune disease (7, 8, 9, 10, 11, 12). Our modern indoor lifestyle limits our sun exposure, and we can only get a small amount of vitamin D from diet (13). According to the lower boundary of the U.S. lab range of 30 ng/mL, as many as 70 percent of Americans are considered deficient (14, 15).

It’s great that awareness about vitamin D deficiency is increasing, with more doctors than ever testing vitamin D levels. However, like many nutrients, vitamin D follows a U-shaped curve, meaning that both low levels and very high levels are associated with negative health outcomes (16). Unfortunately, few practitioners are aware of the dangers of vitamin D toxicity, and many just test serum vitamin D once and recommend a daily 5,000 or 10,000 IU supplement to their patients.

In this article, I’ll discuss the risks of over-supplementation, why you should get most of your vitamin D from sunlight, and the reasoning behind my current approach to vitamin D.

Risks of excess vitamin D supplementation

Vitamin D status is measured by 25(OH)D in blood. We’ll dive further into vitamin D metabolism later, but for now, just understand that this is the precursor to active vitamin D and is generally considered the most accurate single marker to assess vitamin D status. The U.S. laboratory reference range for adequate 25(OH)D is 30 to 74 ng/mL, while the Vitamin D Council suggests a higher range of 40 to 80 ng/mL, with a target of 50 ng/mL (17).

But a large body of evidence in the medical literature strongly suggests that optimal vitamin D levels might be lower than these figures. There is little to no evidence showing benefit to 25(OH)D levels above 50 ng/mL, and increasing evidence to suggest that levels of this magnitude may cause harm. Consequences of vitamin D toxicity include heart attack, stroke, kidney stones, headache, nausea, vomiting, diarrhea, anorexia, weight loss, and low bone density (18).

Furthermore, in most studies, taking vitamin D supplements does not decrease risk of death, cardiovascular disease, or other conditions. Based on an exhaustive review of over 1,000 studies in 2011, the Institute of Medicine recommends a much more conservative range of 20 to 50 ng/mL (19).

Some research on Israeli lifeguards suggests that, contrary to popular belief, vitamin D toxicity from sunlight alone (in the absence of supplementation) is possible (20). That said, it is  much more difficult to achieve toxic levels through sun exposure alone. Sunlight is the optimal source of vitamin D, and has numerous  benefits above and beyond improving vitamin D status.

Beyond vitamin D: The many benefits of sunlight

Vitamin D is really just the tip of the iceberg when it comes to the benefits of sunlight. A recent 20-year study following 29,518 subjects found that those individuals avoiding sun exposure were twice as likely to die from all causes (21). While this study did not assess vitamin D levels, findings from other epidemiological studies suggest that this cannot be accounted for by the increase in vitamin D production alone.

Indeed, humans make several important peptide and hormone “photoproducts” when our skin is exposed to the UVB wavelength of sunlight (22). These include:

• β-Endorphin: a natural opiate that induces relaxation and increases pain tolerance (23, 24)
• Calcitonin Gene-Related Peptide: a vasodilator that protects against hypertension, vascular inflammation, and oxidative stress (25)
• Substance P: a neuropeptide that promotes blood flow and regulates the immune system in response to acute stressors (26)
• Adrenocorticotropic Hormone: a polypeptide hormone that controls cortisol release by the adrenal glands, thus regulating the immune system and inflammation (27)
• Melanocyte-Stimulating Hormone: a polypeptide hormone that reduces appetite, increases libido, and is also responsible for increased skin pigmentation (27)

Exposure to the UVA wavelength of sunlight has also been shown to have benefits, including increasing the release of nitric oxide from storage (28). Nitric oxide is a potent cellular signaling molecule that dilates the blood vessels and thus reduces blood pressure (29).

In addition to the production of photoproducts and release of nitric oxide, sunlight also entrains circadian rhythms. Exposure to bright light during the day activates neurons in the suprachiasmatic nucleus of the hypothalamus, which sends signals to the pineal gland that regulate melatonin production. Disruption of circadian rhythm has been associated with mood disorders, cognitive deficits, and metabolic syndrome (30, 31).

Optimal vitamin D range depends on many factors

So how much do you need? At the first annual IHH-UCSF Paleo Symposium in San Francisco this year, nutritional biochemist Dr. Chris Masterjohn summarized evidence suggesting that optimal vitamin D levels may vary from population to population, despite the fact that there is currently only one reference range used for all patients.

Ethnicity is one major consideration. For example, blacks have lower 25(OH)D than whites in the U.S., yet they typically have much higher bone mineral density. Furthermore, non-Caucasians have lower 25(OH)D levels than Caucasians, even at their ancestral latitudes (32). From these and other studies, it has been suggested that people with non-white ancestry may be adapted to a lower optimal 25(OH)D level than people with white ancestry.

Another factor that influences toxicity is nutritional status. The fat-soluble vitamins A, D, and K work synergistically, and adequate vitamin A and K may protect against toxic effects of excess vitamin D (33). Sufficient levels of potassium and magnesium have also been suggested to protect against vitamin D toxicity (34). Unfortunately, most people are deficient in these micronutrients in the developed world, making them more susceptible to vitamin D toxicity.

What about optimal vitamin D range from an evolutionary perspective? A study on traditionally living hunter–gatherer populations in East Africa found that the Masai and Hadzabe tribes had average 25(OH)D concentrations of 48 ng/mL and 44 ng/mL, respectively (35). These indigenous populations get a great deal of sun exposure but also have very high intakes of vitamins A and K, suggesting that these levels are probably towards the higher end of the optimal range for most people in the modern world.

Using parathyroid hormone levels to individualize vitamin D testing

As we saw in the last section, 25(OH)D lab ranges should vary by population, genetics, and nutritional status. In the absence of specific ranges, we need other biological markers that can help to clarify vitamin D status. To find these biological markers, we need to look at how vitamin D is metabolized.

When UVB contacts the skin epidermis, vitamin D is produced from 7-dehydrocholesterol. This vitamin D then travels in the blood to the liver, where it undergoes primary hydroxylation (the addition of a hydroxyl group, consisting of one oxygen and one hydrogen atom) on the 25th carbon atom. The result is 25(OH)D, which is the metabolite most widely used to assess nutritional vitamin D status. This compound circulates in the blood until it undergoes secondary hydroxylation on the first carbon atom in the kidney, resulting in 1,25(OH)₂D, the active form of vitamin D (36).

You might be wondering: why don’t we test the active form? While certainly informative, the amount of active vitamin D is not directly reflective of nutritional vitamin D status because the secondary hydroxylation step is tightly regulated by parathyroid hormone (37). When the parathyroid glands sense a drop of blood calcium levels, they secrete parathyroid hormone (PTH). PTH stimulates the formation of active vitamin D, which increases calcium absorption in the small intestine and calcium release from bone in an attempt to restore normal blood calcium levels (38). High PTH levels can therefore lead to high 1,25(OH)₂D, low bone mineral density, increased risk of fractures, and osteoporosis (39).

With a basic understanding of this pathway, we can use PTH, calcium, and active vitamin D3 as markers to give us a more complete picture of someone’s vitamin D status. In his presentation at IHH-UCSF, Dr. Masterjohn suggested that serum PTH levels above 30 pg/mL may be indicative of biological vitamin D deficiency when 25(OH)D levels are borderline low. Conversely, if 25(OH)D levels are borderline low or even slightly below the laboratory reference range (e.g., 25 to 30 ng/mL), but PTH is less than 30 pg/mL, it is unlikely that the patient is vitamin D deficient, and supplementation is not warranted.

Instead of focusing on the 25(OH)D level itself, what we really want to achieve is maximum suppression of PTH levels for optimal calcium homeostasis and bone health. Beyond this level, more vitamin D is not necessarily better.

Conclusion

Based on my assessment of the literature and my own clinical experience, I believe the functional range for 25(OH)D is around 35 to 60 ng/mL. However, I can’t stress enough that there is significant variation among populations. For those with non-white ancestry, the optimal range may be a bit lower. For those with autoimmune disease, the optimal range might be a bit higher (45 to 60 ng/mL) to maximize the immune-regulating benefits of vitamin D. Here are a few recommendations for optimizing your vitamin D level.

1. Don’t supplement blindly.
   If your 25(OH)D level is:

• less than 20 ng/mL: you likely need some combination of UV exposure, cod liver oil, and a vitamin D supplement
• 20 to 35 ng/mL: get your PTH tested. If PTH is adequately suppressed (less than 30 pg/mL), supplementing is probably unnecessary.
• 35 to 50 ng/mL: continue your current diet and lifestyle for maintaining adequate vitamin D
• greater than 50 ng/mL: try reducing your vitamin D supplements, and make sure you are getting adequate amounts of the other fat-soluble vitamins to protect against toxicity

2. Get retested!
   Check your levels after three to four months to see if you have achieved or maintained adequate levels of vitamin D. If not, adjust your diet, lifestyle, or supplements accordingly and check again in another three to four months.

3. Get sunlight or UV exposure as your primary form of vitamin D.
   Reap the many benefits of sunlight beyond just subcutaneous production of vitamin D, and reduce your chance of achieving toxic levels. Spend about 15 to 30 minutes, or about half the time it takes your skin to turn pink, in direct sunlight. Sunscreens not only block production of vitamin D, but also all of the other beneficial photoproducts produced in the skin in response to UVB.

4. Mind your micronutrients to protect against toxicity.
   Try cod liver oil as a good source of vitamins A and D and high-vitamin butter oil or pastured butter and ghee for vitamin K. Sweet potatoes, bananas, plantains, and avocados all contain significant amounts of potassium. Considersupplementing with magnesium as it is very difficult to get adequate amounts of this micronutrient from food due to soil depletion.

Take Magnesium for Better Performance: How It Affects Vitamin D, Calcium & Zinc

by Charles Poliquin (web)

Take magnesium for better athletic performance and get the most out of vitamin D and zinc at the same time. New research shows that magnesium enables optimal athletic performance because the body is better able to use energy and perform muscular contractions.

A recent study performed on elite handball players in the journal Magnesium Research found that supplementing with magnesium will increase red blood cell production, and it increases the availability of both zinc and magnesium to support energy production, muscle contractions, and removal of waste products produced by intense exercise.

Magnesium is redistributed throughout the body when you start exercising, which is one reason that studies trying to identify the optimal daily intake of magnesium for different populations have produced inconclusive results. What is clear is that athletes have greater need for magnesium, and 500 mg a day is a reasonable dose. Your needs be higher if you are a heavy sweater or experience symptoms of low magnesium such as muscle spasms, arrhythmias, or unexplained fatigue or weakness when training.

In addition to magnesium’s role in red blood cell production, it is also taken up by fat cells as fat is used for fuel. If you are deficient in magnesium, muscle contraction rate will be impaired because the calcium pump that transports calcium ions to the sarcoplasm of the muscle will be reduced. When this happens, you will feel fatigue, and reduced power and strength.

Zinc is also involved in optimal red blood cell production and it allows for the release of anabolic and fat burning hormones during exercise. It plays an interrelated role with magnesium and calcium, as seen by an interesting study that found that when intra-abdominal pressure is increased—a common occurrence when strength training—brain blood levels of magnesium, calcium and zinc are altered significantly. This study didn’t test optimal levels of these minerals; it only highlighted the close relationship they play physiologically.

In addition, magnesium activates cellular enzyme activity, allowing the body to convert vitamin D into its active form to help bone building. It also leads to the release of the hormone calcitonin, which helps to preserve bone structure and draw calcium out of the blood and soft tissues to be deposited in the bones.

With all of these physiological uses for magnesium, it’s no wonder that this mineral is one of the most important for athletes.  For best results with magnesium, vitamin D, and zinc take 500 mg/day of magnesium from a highly absorbable source such as magnesium glycinate. Researchers suggest that for women, a healthy calcium to magnesium dose is 1:1, whereas men probably do not need to get supplemental calcium since there is some evidence that it can lead to cardiovascular problems.
Also, ensure your vitamin D level is optimal by getting a vitamin D blood test (you want a level above 40 ng/ml).

To test your zinc level,  do a zinc taste test that works because we know that taste and smell are dependent on there being adequate zinc in the body. To do this test, get zinc sulfate and put about 1-2 teaspoons in a cup and sip it, holding it in the mouth. If it tastes just like water, you are very zinc deficient. If you taste something slightly metallic, you are moderately zinc deficient. If it tastes disgusting—strongly metallic and unpleasant—your levels are probably adequate. This test is subject to individual taste perception and it is not 100 percent valid, but it is a good place to start.

9 Steps to Perfect Health – #4: Supplement Wisely

by Chris Kresser (web)

In the first three articles in this series, we discussed which foods to eat and which foods to avoid. In this article we’re going to talk about when to supplement and how to do it wisely. We’ve got a lot of material to cover, so you might want to grab a cup of tea and get comfortable!

There are three principles to supplementing wisely:

• Get nutrients from food whenever possible.
• Take nutrients in their naturally occurring form whenever possible.
• Be selective with your supplementation.

Get nutrients from food whenever possible

Humans are adapted to getting nutrients from whole foods. Most nutrients require enzymes, synergistic co-factors and organic mineral-activators to be properly absorbed. While these are naturally present in foods, they are often not included in synthetic vitamins with isolated nutrients.

In a paper published in the American Journal of Clinical Nutrition called Food Synergy: An Operational Concept For Understanding Nutrition emphasizing the importance of obtaining nutrients from whole foods, the authors concluded:

A person or animal eating a diet consisting solely of purified nutrients in their Dietary Reference Intake amounts, without benefit of the coordination inherent in food, may not thrive and probably would not have optimal health. This review argues for the primacy of food over supplements in meeting nutritional requirements of the population.

They cautioned against the risk of reductionist thinking, which is common in conventional medicine and nutritional supplementation. Instead, they urge us to consider the importance of what they call “food synergy”:

The concept of food synergy is based on the proposition that the interrelations between constituents in foods are significant. This significance is dependent on the balance between constituents within the food, how well the constituents survive digestion, and the extent to which they appear biologically active at the cellular level.

They go on to provide evidence that whole foods are more effective than supplements in meeting nutrient needs:

• Tomato consumption has a greater effect on human prostrate tissue than an equivalent amount of lycopene.
• Whole pomegranates and broccoli had greater antiproliferative and in vitro chemical effects than did some of their individual constituents.
• Free radicals were reduced by consumption of brassica vegetables, independent of micronutrient mix.

In short: get nutrients from food, not supplements, whenever you can.

Take nutrients in their naturally occurring form whenever possible

Synthetic, isolated nutrients don’t always have the same effect on the body. It matters whether the nutrients have been produced by technologic or biological processes, because industrial processing sometimes creates an entirely new compound with different physiological actions. Trans fat produced in ruminant animals (such as conjugated linoleic acids in dairy products) are beneficial to health, whereas trans fats produced in the processing of industrial seed oils are highly toxic.

Folic acid is another example. The naturally occurring form of folate is not folic acid, a compound not normally found in food or nature, but tetrahydrofolate. While folic acid can be converted into folate, that conversion is poor in humans. It’s also important to note that unlike natural folate, folic acid does not cross the placenta. This is significant because folate is a crucial nutrient for pregnancy, and while folic acid can prevent neural tube defects it doesn’t have the other beneficial effects of folate. What’s more, several studies have shown that folic acid – but not natural folate – increases cancer risk. Unfortunately, folic acid is what’s often used in multivitamins, because it’s significantly cheaper than natural folate.

Be selective with your supplementation.

Multivitamins have become increasingly popular: half of Americans currently take one. But is this a good idea? Most studies show that multivitamins either provide no benefit, or may even cause harm. A study in the Archives of Internal Medicine showed that multivitamins have little to no influence on the risk of common cancers, CVD or total mortality in postmenopausal women. A now infamous meta-analysis in the Journal of American Medical Association, which looked at over 68 trials with 230,000 pooled participants, found that treatment with synthetic beta carotene, vitamin A and vitamin E may increase mortality.

The problem with multivitamins is that they contain too little of beneficial nutrients like magnesium, vitamin D and vitamin K2, and too much of potentially toxic nutrients like folic acid, calcium, iron and vitamin E. This means that multivitamins can actually cause nutrient imbalances that contribute to disease. Another problem is that multivitamin manufacturers often use the cheapest possible ingredients, such as folic acid instead of natural folate – the consequences of which we discussed above.

Which supplements may be necessary?

At this point you might be thinking I’m against supplementation entirely. Not so. No matter how well we eat, some nutrients are difficult to obtain enough of from food alone. There are also circumstances where are need for certain nutrients may increase, such as vitamin C during infections and magnesium with blood sugar imbalances or metabolic problems. In these cases, it makes sense to supplement selectively with beneficial nutrients.

The five nutrients I recommend most people supplement with are:

• Vitamin A
• Vitamin D
• Vitamin K2
• Magnesium
• Vitamin C

Vitamin A (Retinol)

Vitamin A is important catalyst for a variety of biochemical processes in the body. It’s required for assimilation of protein, minerals and water-soluble vitamins, and it also acts as antioxidant > protecting body against free-radical damage and diseases like cancer. Vitamin A plays a crucial role in reproduction, promoting full-term pregnancy and proper development of face (eyes, nose, dental arches & lips).

The RDA for vitamin A (2,600 IU) is woefully inadequate, and even then, over 25% of American consume less than half of the recommended amount. Native populations such as the traditional Inuit – which were free of modern, degenerative disease – got much more vitamin A than the average American. The Greenland Inuit of 1953, prior to much contact with the Western world, got about 35,000 IU of vitamin A per day.

Vitamin A (retinol) is only found in significant amounts in organ meats, which explains why many Americans don’t get enough of it. If you follow my recommendations in #2: Nourish Your Body, and you do eat organ meats (especially liver), you’re probably getting enough vitamin A and thus don’t need to supplement. However, if you’re like most Americans and you’ve never eaten liver in your life, you would benefit from supplementing with A.

There’s been a lot of discussion in the media about the toxicity of vitamin A. Some researchers and doctors now recommend avoiding cod liver oil because of this concern. Even Dr. Mercola has jumped on the “vitamin A is toxic” bandwagon. But is this true?

It is true that vitamin A is potentially toxic. Some evidence suggests that excess vitamin A increases the risk of osteoporosis. For example, this study showed both low and high serum A carried double risk of fractures as did optimal levels.

But if we dig deeper we find that excess vitamin A only causes problems against a backdrop of vitamin D deficiency. In his excellent article Vitamin A on Trial: Does Vitamin A Cause Osteoporosis, researcher Chris Masterjohn summarizes evidence demonstrating that vitamin D decreases the toxicity of and increases the dietary requirement for vitamin A. Studies show that supplementing with vitamin D radically increases the toxicity threshold of vitamin A. In a hypothetical 160 lb. person, vitamin D supplementation increases the toxicity threshold of vitamin A to more than 200,000 IU/d. You’d have to eat 22 ounces of beef liver or take 5 TBS of high vitamin CLO each day to get this amount. Not likely!

To meet vitamin A needs (assuming you’re not up for eating organ meats), I recommend taking high vitamin cod liver oil (CLO) to provide a dose of 10-15,000 IU per day. Cod liver oil is really more of a food than a supplement, but since it’s not a normal part of people’s diet we’ll consider it as a supplement. CLO is an ideal vitamin A source because it also contains vitamin D, which as we just learned, protects against the toxicity of A.

Vitamin D

Much has been written about the need for and benefits of vitamin D supplementation over the past several years – and with good reason. It’s absolutely critical for health, and up to 50% of Americans are deficient.

We can get vitamin D from two sources: food, and sunshine. Seafood is the only significant source of vitamin D, but you’d still have to eat a lot of it to get enough. 8-9 ounces of herring provides about 2,000 IU of vitamin D, which is a minimum daily requirement for most people to maintain adequate blood levels.

Sunlight converts a precursor called 7-dehydro-cholesterol in our skin to vitamin D3. This D3, along with the D3 we get from food, gets converted by the liver into 25-hyrdroxy-vitamin D (25D), which is what typically gets measured when you have a vitamin D test. The optimal 25D level is somewhere between 35 and 50 ng/mL.

Contrary to what some researchers and doctors have recommended, there’s no evidence that raising blood levels of 25D above 50 ng/mL is beneficial, and there’s some evidence that it may cause harm. Studies show that bone mineral density peaks at 45 ng/mL and then falls again as 25D levels rise above 45. Other studies have shown that the risk of kidney stones and CVD increase with high 25D levels, due to elevated serum calcium levels that accompany excess vitamin D.

However, we also know that vitamin A and vitamin K2 protect against vitamin D toxicity, and vice versa. As I explained in the vitamin A section, fat soluble vitamins exist in a synergistic relationship. It’s possible that the people in the studies above that experienced problems with excess 25D levels were deficient in vitamin A or K2, or both. This is why it’s so important to supplement with all of the fat-soluble vitamins together.

What about sunlight? Well, in summer mid-day sun with pale skin, 30 minutes of direct sunlight will produce 10-20,000 IU of vitamin D. But this is a best case scenario. With darker skin, or different times of year, or buildings that block the sunlight, or increased time spent indoors, we won’t be producing that much. It’s also true that aging, overweight and inflammation reduce our conversion of sunlight to vitamin D. This is why sunlight alone isn’t normally a sufficient source of vitamin D.

With this in mind, most people should supplement with D. The amount needed to maintain blood levels of 35-50 ng/mL varies depending on some of the factors I’ve listed above, but in my clinical experience it’s usually somewhere between 2,000 – 5,000 IU. With vitamin D, it’s important to test your levels, begin supplementation, and then re-test a few months later to determine the correct maintenance dose.

As with vitamin A, the best source of vitamin D is high-vitamin cod liver oil. It contains not only vitamins A & D, but also natural vitamin E and other quinones.

Vitamin K2

Vitamin K2 may be the most important vitamin most people have never heard of. It’s needed to activate proteins and it also regulates calcium metabolism (keeping it in the bones and teeth where it belongs, and out of the soft tissue where it doesn’t belong). Elevated blood calcium significantly increases the risk of cardiovascular disease (CVD), which explains why vitamin K2 has been shown to prevent atherosclerosis and heart attacks. It also strengthens bones.

Unfortunately, many (if not most) of Americans are deficient in vitamin K2. It’s important to point out that vitamin K2 is not the same as vitamin K1, which is found in green, leafy vegetables like kale and collards. Some K1 is converted into K2 in our bodies, but that conversion is inefficient in humans. It is efficient, however, in ruminant animals – which is why grass-fed dairy is the most convenient source of vitamin K2 in the diet. This is only true in animals raised on pasture, because it is eating the K1-rich grass that allows them to convert it into K2.

Most people should aim for at least 100 mcg/d from a combination of food and supplements. If you eat a large amount of cheese from grass-fed cows and pastured egg yolks, you may be able to get this amount from food alone. 100 g of hard cheese contains 67 mcg, and 6 pastured egg yolks contain about 32 mcg. Otherwise, supplementation is probably beneficial. I recommend a dosage of 1 mg/d in the MK-4 form, which is the form of vitamin K2 found in pastured dairy and the one shown to have the most benefit in clinical studies. There is another form, MK-7, that is found in fermented foods like natto, but it has not demonstrated the same properties as MK-4 in clinical studies.

Magnesium

There are few compounds in the body more important to overall health than magnesium. Over 300 enzymes need it, including every enzyme associated with ATP, and enzymes required to synthesize DNA, RNA and proteins. Magnesium also plays an important role in bone and cell membranes, as it helps to transport ions across the membrane surface.

Studies show that most Americans are deficient in magnesium. The median intake across all racial groups is far below the RDA, which is 420 mg/d for men and 320-400 mg/d for women. Although half of Americans take a multivitamin daily, most don’t contain enough magnesium to prevent deficiency.

Magnesium is also difficult to obtain from food. Nuts and seeds are the highest source, but it’s difficult to eat enough of them to meet magnesium needs without getting too much polyunsaturated fat. Another issue is that magnesium levels in food have dropped as modern soils have become increasingly depleted. What this means is that if you’re not supplementing with magnesium, you’re probably not getting enough.

And magnesium deficiency is no small thing. It has serious – even fatal – consequences. It produces symptoms like muscle cramps, heart arrhythmias, tremor, headaches & acid reflux, and it’s associated with CVD, hypertension, metabolic syndrome, diabetes, migraines, PMS, asthma, hypothyroidism. In fact, it’s hard to find a modern disease magnesium deficiency isn’t associated with.

Because of this, I think everyone should supplement with magnesium. Intake of 400 – 800 mg/d from a combination of food and supplements is an optimal range to shoot for. Since most people get less than 250 mg/d from food, a dose of 400 – 600 mg/d in supplement form is ideal. I recommend using chelated forms of magnesium like glycinate and malate, because they’re better absorbed and tend to have fewer side effects.

Vitamin C

Vitamin C is needed for building the structural components of the body, and for maintaining levels of glutathione, the master antioxidant in the body. But vitamin C deficiency is also common: studies suggest that 34% of men and 27% of women don’t get enough. This is especially true for the elderly and those struggling with chronic illness.

400 mg/d is the saturation range in healthy people, and that number is probably higher in the elderly and the sick. As with the other micronutrients in this article, it’s difficult to obtain adequate levels of vitamin C from the diet. Acerola cherries are the highest food source, with 1677 mg per 100g. A cup of cooked red peppers has 235 mg, which is one of the highest dietary sources.

I’m somewhat less certain about the need to supplement with vitamin C, but in general I recommend approximately 500 mg to 1 g of vitamin C each day. If you’re dealing with a chronic health challenge, or fighting an infection, you can take several grams a day with no toxic effects. It’s best to space the doses out to avoid diarrhea, however.

Other contenders

In addition to the fat-soluble vitamins A, D & K2, and magnesium and vitamin C, some may want to consider supplementing with selenium and iodine. Selenium plays important role in thyroid function, which affects every aspect of physiology. The recommended dose is approximately 200 mcg/d.

Selenium is plentiful in organ meats, ocean fish, and in brazil nuts. One brazil nut contains 100 mcg of selenium, but it also contains a whopping 1 g of omega-6 linoleic acid, which as you know from previous articles in the series, we want to limit significantly. This is why I don’t recommend brazil nuts as a source of selenium. Ocean fish are also good sources of selenium. 100 g of cod contains about 150 mcg.

Iodine also plays a crucial role in thyroid function, and it prevents brain damage and strengthens the immune system. The amount iodine needed for thyroid function is incredibly small: we need about a teaspoon of iodine over a lifetime to avoid deficiency. I’m not convinced humans need to supplement with iodine above what can be obtained from seafood, but some research does suggest that increased intake of iodine is beneficial. This is especially true if you’re fighting a chronic infection or dealing with a hypothyroidism caused by iodine deficiency.

But be careful: iodine can trigger and flare autoimmune diseases, especially Hashimoto’s and Graves’(autoimmune thyroid disease). In the U.S., 9 out of 10 women with hypothyroidism actually have Hashimoto’s, so the typical advice to supplement with iodine if you are hypothyroid is dangerous. I’ve written extensively about this in my special report on thyroid disease.

For those without autoimmune disease, a dose of 12.5 mg – 50 mg per day may be beneficial, but it’s best to work up slowly over time, beginning at a much lower dose.