Dietary Sources of Vitamin D

Why do we need Vitamin D?

Some nutrient sources contain dense amounts of Vitamin D3, and it can be acquired in significant amounts by including them in one’s diet, though in many instances the amounts would probably fall below recommended levels. This is partly because during the course of evolution in Equatorial zones, skin exposed to solar radiation became the principal way of humans acquiring it, rather than through our diet. Furthermore not all Vitamin D is actually absorbed when it is eaten. It’s absorption is mainly at the distal (far) end of the large intestine. Vitamin D is mainly stored in the liver and kidneys of mammals, but not for long periods of time. Predatory carnivores like wolves and cats, as well as human beings who, until the advent of agriculture, were also predators, can acquire Vitamin D from consuming the organs of prey animals. Humans were (and are) also food collectors of bird eggs and mushrooms, which are also good sources of Vitamin D.

Sources of Vitamin D3 in food


The highest concentrations of D3 are found in oily fish. It accumulates in fish livers after becoming concentrated through the food chain, beginning with algae and moving up through small fish eaten by larger fish that are in turn eaten by ever larger fish. Cod liver oil is the densest nutrient source available at reasonable cost. And oily fish, especially salmon, are also an excellent and widely available source.

Sardines, herring, mackerel, swordfish, trprocessing-salmon-fish-meat-725x472out and tuna also supply significant amounts of Vitamin D. The extra benefit from all these fish are that they contain Omega 3 fatty acids, a potent fat with many additional health benefits. Sardines, herring and baby mackerel are also eaten whole and so their small bones can also increase calcium intake.


Vegans as well as other vegetarians can rely on many mushrooms for some of their vitamin D. Shiitake mushrooms hold significant quantities and are a source of protein as well. Even less costly portobello mushrooms also contain useful amounts of D and are widely available.


Food Preparation to minimize loss of Vitamin D

How these foods are prepared is important in order to maximize the dose received. Frying fish in oil reduces the Vitamin D available because it is a fat soluble vitamin–and can be dissolved all along the cooking surface of the fish where it is taken up by the oil in which it’s cooked. Steamed, baked or broiled fish retain more Vitamin D. Higher temperatures can destroy some vitamin D too, but if the fish is steamed, the temperature never exceeds that of boiling water and all the benefits, as well as the taste of the fish, are retained.

Cow’s milk

Cow’s milk is widely fortified with Vitamin D (as are many processed foods). Vitamin D fortification in developed countries was undertaken as an inexpensive and effective way to prevent “Rickets” which is a serious disorder of bone development mainly found in children, especially those who are desperately poor. Vitamin D is also found in significant amounts in milk from dairy herds that rely on pasture for forage. It is present in new-mown hay because it’s produced by dying and drying plants, specially alfalfa. Animals that consume large amounts of such forage produce milk with Vitamin D3 in higher amounts than those fed other types of feed in barns. Importantly cow’s milk is fortified with D3–so a true benefit is derived. Fortification is an inexpensive and effective way for public health campaigns to help all people to avoid the most serious vitamin D deficiencies, particularly rickets. However, eating many processed foods to gain vitamin D is not a good idea because many of these possess a long list of other far less desirable attributes.holsteins in field


Dietary acquisition of vitamin D may be problematic for many individuals due to dietary restrictions associated with biological and cultural sensitivities including: vegetarianism (either as a religious or ethical stance), lactose intolerance related to aging or the basic physiology of most of the global population, and dietary restrictions related to other health issues and medical treatments. Dietary supplementation with Vitamin D3 is recommended for nearly all people who do not spend significant amounts of time exposed to the sun. That means most of us.

Astaxanthin: Prince of Antioxidants

March 20, 2016

Astaxanthin has been hailed by some as the “King of Antioxidants” with incredible health benefits and claims that it can cure everything from sunburn to cancer. If astaxanthin is that good, why haven’t most people ever heard of it?

The idea behind the claims is that astaxanthin has significant anti-inflammatory and anti-oxidative properties which lead to many health benefits, including protection from sun damage, improved athletic performance, protection from heart disease, eye disease, cancer and longer lives.

The question is, how valid are these claims? It is our aim to explain to you what astaxanthin is, what the health benefits are and how much substance there is behind the claims.

What is Astaxanthin?

Astaxanthin is a naturally occurring fat-soluble carotenoid found in microalgae. It works its way up the food chain and is what makes krill, shrimp, trout, salmon and flamingos pink. Even though it has not received the same attention as other carotenoids, such as vitamins C and E, it is possibly a far more powerful antioxidant than these and other better known carotenoids.

What are Carotenoids?images-4

Identifiable by their orange, yellow, and red pigments, carotenoids are found in many plants, algae, and bacteria. There is a significant amount of scientific evidence that carotenoids act as antioxidants in the body, protecting against cellular damage. There are over 600 carotenoids, with beta-carote
ne, alpha-carotene, lutein, zeaxanthin, lycopene, and astaxanthin being the most common.

Many studies have shown that people consuming diets rich in carotenoids from natural foods, such as fruits and vegetables, are healthier, and live longer because carotenoids are efficient free radical scavengers and reduce oxidative stress.(1)

urlWhat is an Antioxidant?

In simple terms, antioxidants protect the body from free radicals. Free radicals are atoms or groups of atoms with unpaired electrons, and occur when oxygen interacts with certain molecules. Free radicals can inflict damage by causing a long series of chain reactions that prompt oxidative stress.

Oxidative stress is the imbalance between the production of free radicals and the ability of the body to counteract their harmful effects. One of the principal harmful effects of oxidative stress is inflammation which ultimately causes damage to cell structures, including the lipids and membranes, proteins, and DNA.

The body has a defense system of antioxidants which serves to prevent free radical damage.
Antioxidants interact with free radicals and stop the chain reaction before the vital molecules are damaged. The body cannot manufacture antioxidants and so they must be supplied from our diet or supplements.

Astaxanthin and Other Carotenoids

While similar to other carotenoids with many of the same health benefits, some believe that astaxanthin is superior because it has a unique structure and works in some very unique ways. It is thought that unlike other carotenoids, astaxanthin positions itself across the entire cell membrane, protecting all parts of the cell, and is able to trap radicals both inside of the membrane and at the membrane surface.

This claim is a significant one because it provides a rationale for why astaxanthin may be more effective than other antioxidants. However, the only scientific backing we have been able to find for this claim is a 2001 Japanese study which compares the effectiveness of beta carotene and astaxanthin on free radicals. This study found that astaxanthin was twice as effective, and concluded that its effectiveness was due to its unique ability to trap free radicals near the membrane surface and in the interior of the membrane.(2)

We could not find any follow up studies that investigate this important claim.

There are other claims made about astaxanthin that also attempt to distinguish it from other carotenoids. One claim is that astaxanthin acts on at least five different inflammatory pathways and can handle more free radicals at any given time than other antioxidants. Another claim is that, unlike other antioxidants, it does not become pro-oxidant because it forms an electron cloud around itself, so that when free radicals come by to steal electrons they are absorbed into the cloud and neutralized. Unfortunately, we have been unable to find any scientific studies that effectively back up these claims. The authority for these theories seems to be Dr. Robert Corish MD, who is professed to be one of the world’s leading experts on astaxanthin. He may well be, but that does not in itself constitute valid scientific evidence for the propositions. And there is also the fact that he serves as the medical director for the largest producer of astaxanthin, which…. we’ll let you draw your own conclusions.

Another bold and often repeated claim is that astaxanthin is the most potent antioxidant nature has to offer and that it is 800 times greater than CoQ10, 75 times greater that ALA, 550 times greater than green tea catechins and 6,000 times greater than Vitamin C. This claim seems to be based on a 2007 Japanese study which compared several antioxidants to determine their ability to combat singlet oxygen.(3) Even though this is an important study, it was not a human study or even an animal study, and it was funded by the leading producer of astaxanthin. And even the study concluded that far more research is required before these claims can be conclusively validated.

None of this means that astaxanthin does not have many health benefits and may indeed be the best of the carotenoids as an antioxidant. For example, in an assay study in 2000, astaxanthin was shown to have the highest antioxidant activity compared to other carotenoids.(4)

We will now look at some of astaxanthin’s health benefits that have at least some scientific validation.

Can Astaxanthin Improve Athletic Performance?

One of the benefits of astaxanthin that has piqued the interest of researchers is its ability to enhance athletic performance. Whether you are an elite athlete or just interested in increasing your tolerance for yard work, can this carotenoid help?

In a 2012 study, astaxanthin was shown to have positive benefits with regard to exercise-induced stress. This was a double blind study covering a ninety day period. Thirty-two elite male soccer players were given either a placebo or astaxanthin (4 mg/day). Each week they trained 5 to 7 days for 10 to 15 hours. Those taking astaxanthin showed less oxidative stress, inflammation and an enhanced immune response. (5)

Can Astaxanthin Protect Your Skin?

It would appear so, given the results of two 2012 significant Japanese human clinical studies. In one, an open-label non-controlled study, 30 healthy women were given 6 mg per day oral supplementation and 2 ml of a topical solution of astaxanthin for 8 weeks. The researchers found that the women showed significant improvement with regard to wrinkles, elasticity and age spots.

The other, a randomized double-blind placebo controlled study, involved 36 healthy male subjects. For 6 weeks the subjects were given the same supplementation as the women and showed similar results.(6)

A preliminary clinical trial of 25 individuals, conducted by an astaxanthin manufacturer in the course of patent research, found that after two weeks of supplementation of 4 mg per day, there was a statistically significant increase in the amount of time necessary for UV radiation to redden skin.(7)

Can Astaxanthin Protect Your Heart?

Researchers are also looking into claims that astaxanthin can benefit heart health. A 2006 study examined astaxanthin’s effects on rats with hypertension (high blood pressure), and results indicated that it may help to improve elastin levels and arterial wall thickness.(8)

Other claims include the idea that astaxanthin can prevent heart disease and help lower cholesterol, but there does not yet appear to be sufficient evidence to support these claims.

Can Astaxanthin Help You Live Longer?

A study has shown that doses as low as 2 mg/day for 4 weeks lead to a significant reduction in the measurable oxidative DNA damage by about 40%.(9)

Oxidative stress or the production of free radicals is thought to be a principal mechanism of aging. Both slowing down the production of free radicals or increasing antioxidants to neutralize free radicals ought to slow down the aging process.

In a randomized double-blind, placebo-controlled study in 2010, young healthy women were given astaxanthin supplements (0, 2 or 8 mg/day) for 8 weeks. They found that those taking astaxanthin showed less oxidative stress and inflammation, and an enhanced immune response. Interestingly, both doses of astaxanthin decreased DNA damage and enhanced the immune response. (10)

What are Some Other Health Benefits of Astaxanthin?

One study found short and long term benefits for the treatment of breast cancer, including reduced growth of breast cancer cells.(11)

Astaxanthin may also have a future in the treatment of carpal tunnel syndrome, and joint pain, including conditions like rheumatoid arthritis, which affects nearly one in five Americans. However, results so far have been mixed.(12)

In a 2005 study, astaxanthin showed positive results for male fertility. Over the course of three months, the double-blind study examined 30 different men who were previously suffering from infertility. The researchers saw improvements in sperm parameters, like count and motility, and improved fertility in the group who received a strong dosage of astaxanthin. As this was a relatively small-scale study, more evidence and research is needed to support this claim.(13)

An interesting 2009 study found that: astaxanthin has a protective efficacy against several deleterious effects caused by high glucose exposure and proposed that astaxanthin should be explored further as a potential antidiabetic remedy for the treatment of diabetic nephropathy.(14)

Sources of Astaxanthinimgres-6

Microalgae produce astaxanthin to protect themselves from various environmental stresses including excessive UV radiation.(15) H. pluvialis has the highest levels of astaxanthin found in nature at 40,000 parts per million. The other main sources are: phaffia yeast 10,000, arctic shrimp 1,200, krill 120, plankton 60 and salmonids 5.(16)

At this point if you feel that astaxanthin would be beneficial for you, and unless you eat a lot of wild caught alaskan salmon or a lot of arctic shrimp, supplementation of 4 mg per day is probably a good idea.


Even though there are a growing number of scientific studies, most of them are small and not large randomized controlled studies. Nonetheless, some of the existing studies do provide compelling evidence of health benefits.

Therefore, while the jury is still out on some of the health claims made with regard to astaxanthin, you can be pretty certain that, as an antioxidant, astaxanthin is good for you. The title of “King of the Carotenoids” if nothing else, is premature; perhaps a better title is “Prince of the Carotenoids” and in the future we will see if it can ascend to the big throne.


imgres-1 imgres-2

Supplementing what we eat with added vitamins, minerals and  herbs is a complex topic.  If the perfect foods were always available, supplementation would not be needed. But in an imperfect world, sometimes supplementing diets is important.

Reasons people might need to supplement their diets include: dietary restrictions due to chronic illness, age-related problems absorbing nutrients, depletion from therapies (“chemo” or radiation), ethical or religious beliefs, dangerous interactions between some foods and certain drugs, or food sensitivities and allergies.  Many foods produced by industrial processes also contain lower amounts of vitamins than their wild counterparts. 

See these articles on supplements

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Vitamin K2: The Mystery Vitamin

February 21, 2016

Most people and many health care professionals have never heard of Vitamin K2. This is truly unfortunate since it plays a key role in many health concerns, is almost non-existent in Western diets and could well be the “missing link” between our diet and osteoporosis, as well as cardiovascular disease.

What is Vitamin K?  capsules-of-omega-3

Since its discovery in 1929, vitamin K has been known primarily for its crucial role in the blood-clotting process. Vitamin K represents a family of fat soluble vitamins, of which K1 and K2 have been found to be useful for general health purposes.(1)

It was not until 1975 that researchers at Harvard Medical School identified osteocalcin, a bone protein, which led to the discovery of vitamin K2 as distinct from vitamin K1.

Since that time, scientists have uncovered compelling evidence that vitamin K2 plays an important role in bone health, as well as playing a significant role in preventing heart disease and other health issues.

What is the Difference Between K1 and K2?

Vitamin K1 is well known for being crucial for proper blood clotting.

Vitamin K2 importance goes far beyond proper blood clotting; there is a growing body of clinical evidence demonstrating its crucial significance in the fight against the most common and devastating diseases of our time: osteoporosis and cardiovascular disease.(2) These conditions contribute to significant health-care costs, are the most common causes of death worldwide. Both can be linked to a deficiency in vitamin K2.

Vitamin K2 can be further divided into several different subtypes, but the most important ones are MK-4 and MK-7.

What is the Connection Between Vitamin K2, Vitamin D and Calcium?

There is no question that calcium is an incredibly important mineral. It is far more than just a building material for bones and teeth; it plays a crucial role in all kinds of biological processes. (3)

So why is it that recent studies, including one published in the prestigious British Medical Journal, say there is no evidence that increasing calcium intake through supplementation prevents fractures and that supplementation should not be recommended?(4)

It would appear that there is more to the story. Is Vitamin D the missing component? Its importance in bone development is well established.(5) There is no doubt as to the importance of vitamin D to our health. For a detailed discussion, please refer to our article: The Growing Pandemic of Vitamin D deficiency:

There is another significant factor to be considered and that is cardiovascular disease. Many studies are now showing that calcium supplementation causes an increased risk of cardiovascular disease for both men and women.(6)

The Calcium Paradox

Dr. Kate Rheaume-Bleue, a naturopathic physician, has authored what we believe is one of the best books on this important topic: Vitamin K2 and the Calcium Paradox: How a Little Known Vitamin Could Save Your Life.

“When you take vitamin D, your body creates more of these vitamin K2-dependent proteins, the proteins that will move the calcium around. They have a lot of potential health benefits. But until the K2 comes in to activate those proteins, those benefits aren’t realized. So, really, if you’re taking vitamin D, you’re creating an increased demand for K2. And vitamin D and K2 work together to strengthen your bones and improve your heart health.

… For so long, we’ve been told to take calcium for osteoporosis… and vitamin D, which we know is helpful. But then, more studies are coming out showing that increased calcium intake is causing more heart attacks and strokes. That created a lot of confusion around whether calcium is safe or not. But that’s the wrong question to be asking, because we’ll never properly understand the health benefits of calcium or vitamin D, unless we take into consideration K2. That’s what keeps the calcium in its right place.”

In simple terms, it appears that both vitamin K1 and k2 modify proteins to allow them to bind to calcium and in this way activate the calcium binding properties of proteins.(7)

Vitamin K1’s primary function is in the liver to activate calcium-binding proteins involved in blood clotting, while vitamin K2 is used by the body to activate proteins that regulate where calcium ends up in the body. (8)

Vitamin K2 and Heart Disease

In a landmark study known as the Rotterdam study, those who had the highest intake of Vitamin K2 were 52% less likely to develop calcification of the arteries, and had a 57% lower risk of dying from heart disease, over a 7-10 year period. (9)

Another study of 16,057 women found that participants with the highest intake of vitamin K2 had a much lower risk of heart disease. For every 10 micrograms of K2 they consumed per day, the risk of heart disease was reduced by 9%. (10)

Unfortunately, this very important topic still requires further study in the form of large controlled trials. The two studies referred to above are observational studies, which do not prove cause and effect.

How do Vitamin D and K2 Work Together?

Vitamin D allows the body to absorb calcium from the intestines into the bloodstream, but it does not take the calcium to where it needs to go. That is where vitamin K2 comes in. Vitamin K2 activates two important enzymes, Matrix Gla-protein (MGP) and Osteocalcin, that move calcium around the body. When our bodies are deficient in K2, this very important function does not occur, and calcium ends up being deposited in our arteries instead of our bones, leading to a multitude of health problems.

Vitamin D’s role in the transit of calcium is equally critical, and it works synergistically with vitamin K2. When Vitamin D is deficient, K2 is left without an opportunity to escort calcium away from arteries and into bones. If vitamin D is present in sufficient quantity but you are lacking vitamin K2, calcium is likely to build up in arterial walls leading to many health issues.

Lack of vitamin K2 results in the “Calcium Paradox”, where too little calcium is utilized by the bones, resulting in weak bones, and excess calcium accumulates in the arteries, making them stiff and inelastic.

In a peer reviewed article in the Oman Medical Journal entitled Vitamin K Dependent Proteins and the Role of Vitamin K2 in the Modulation of Vascular Calcification: A Review, the authors concluded: “Vitamin K2 has promising potential to be used as treatment or prevention for the the development of vascular calcification, especially in at risk patient groups with high incidence of calcification or vitamin K deficiency.” (11)

What we have is a persuasive argument based on biological grounds and strong correlations from observational studies. Given that cardiovascular disease is the world’s most common cause of death, the importance of further study can not be overstated.
The American Heart Association reports that cardiovascular disease killed 17.3 million people in 2015, with the number expected to rise to 23.6 million by 2030. (12)

What are the Best Food Sources of Vitamin K2?

Our gut bacteria produce some K2 for us and we convert a small amount of K1 to K2 in our liver, but we must depend on dietary sources for most of our K2 requirement.

Vitamin K2 is produced by specific bacteria and the primary food source of vitamin K2 is natto (a Japanese fermented soybean dish), goose liver, and the fat (egg yolk, butter and lard) of grass-fed animals.


Natto is not widely available and is very much an acquired taste. Goose liver is a rare delicacy at best and quite expensive. What used to be our best source – animal fats – is now almost entirely lacking in K2 because of the diet of commercially raised animals. These animals need the chlorophyll in grass or other green food to convert K1 to K2 for us.

To the extent that vitamin K2 is present in dairy products, it is mostly in certain types of cheeses, such as Gouda, Brie, and Edam. It is quite difficult to get enough vitamin K2 from the standard Western diet, especially if you do not eat K2-rich natto, so taking a supplement may be the best strategy for most people.



Vitamin K2 Supplements?

There are several different forms of vitamin K2. The two primary ones are the only ones available in supplement form: menaquinone-4 (MK-4) and menaquinone-7 (MK-7).

MK-4 has a very short biological half-life of about one hour. In addition, in supplement form, the MK-4 products are synthetic, thus making it a poor candidate as a dietary supplement.

MK-7 stays in your body longer; its half-life is three days, meaning you have a much better chance of building up a consistent blood level. MK-7 comes from a natural fermentation process from natto.
Furthermore, it has recently been shown that MK-7 also helps prevent inflammation by inhibiting pro-inflammatory markers produced by white blood cells called monocytes.(13)

With regard to the appropriate dosage, some studies have shown as little as 45 micrograms per day is sufficient. Dr. Dennis Goodman, the chair of the Department of Integrative Medicine at New York University (NYU), in his excellent book, Vitamin K2: The Missing Nutrient for Heart and Bone Health, recommends taking 180 micrograms per day in the form of MK-7 and if you choose to eat natto, all you need is about one teaspoon to meet your 180 micro-gram target.

On the positive side, unlike most fat soluble vitamins, vitamin K2 is virtually non-toxic and there is not much danger of overdosing.(14) Finally, because it is fat soluble, it is best to take your vitamin K2 supplement with a healthy fat, like coconut oil, to improve its absorb-ability.

How Can you Tell if you are Vitamin K2 Deficient?

It is not easy. Unlike Vitamin D there is no easily available way to screen or test for vitamin K2 deficiency. Vitamin K2 cannot so far be measured directly; it is measured through an indirect assessment of undercarboxylated osteocalcin. Unfortunately, this test is still not commercially available.

Without an available test, we are left with looking at lifestyle factors that may indicate signs of deficiency. In general, if you have any of the following health conditions, you are likely deficient in vitamin K2: Osteoporosis, Heart disease or type 2 diabetes. In addition, given the low likelihood that you are getting very much vitamin K2 from your diet, its low toxicity and its potential health significance, it makes sense for virtually everyone to supplement.

Recent Studies Pertaining to Vitamin K2 and its Health Benefits

A study published by the European Prospective Investigation into Cancer and Nutrition (EPIC) has revealed that increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 percent. The authors point out that the benefits of K2 were most pronounced for advanced prostate cancer, and, importantly, that vitamin K1 did not offer any prostate benefits. The findings were based on data from more than 11,000 men taking part in the study.(15)

In another interesting study published in the Oxford Journals in 2013, two hundred chronic kidney dialysis patients suffering from advanced calcification of the arteries were recruited to randomly receive 360, 720 or 1080 µg of MK-7 three times weekly for 8 weeks. They found that the calcification levels decreased by 17, 33 and 46% in the respective groups. They concluded that MK-7 “supplementation may be a novel approach to prevent vascular calcifications in chronic haemodialysis patients.(16)

These studies form part of a small but growing body of science supporting the potential health benefits of vitamin K2 for bone, cardiovascular and prostate health.


There remains a desperate need for large randomized studies on K2 and its potential health benefits. However, the studies that do exist are very persuasive as to vitamin K2’s health benefits. Since vitamin K2 has been shown to be biologically effective, it is clearly an important nutrient for human health, although one of the most poorly understood by medical authorities and the general public.  Our apple rating:  5




The Growing Pandemic of Vitamin D Deficiency

March 22, 2016

sunshine addresses Vitamin D deficiencyThere is virtually no aspect of your health that is not affected by Vitamin D.  We have vitamin D receptors throughout our bodies, including the heart, kidneys, brain, colon, muscle and immune cells. This wide distribution of receptors highlights the importance of this vitamin to many of the body’s functions, and helps to explain why vitamin D deficiency affects not only bone health, but also other systems in the body. Vitamin D deficiency has been linked to various types of cancer, heart disease, depression, multiple sclerosis, lupus, high blood pressure, weight gain, diabetes, infections, colds, flu and a growing list of other illnesses.

Vitamin D is a fat-soluble vitamin that is naturally present in few foods, added to some, available as a dietary supplement and produced when ultraviolet rays from sunlight strike the skin and triggers vitamin D synthesis.

How does your Body Make Vitamin D?

Vitamin D obtained from the sun, food, and supplements is biologically inert and must undergo two processes in the body to be active. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D]. The second occurs primarily in the kidney and forms the active 1,25-dihydroxyvitamin D [1,25(OH)2D] or calcitriol.

Do I need to take Vitamin D Supplements?

The simple answer is that we all need vitamin D and that most of of us are able to get at least some of the required amount from our diet and sun exposure for at least part of the year.

There is a mistaken belief that as little as ten minutes of daily sunlight exposure on your hands and face will provide you with your daily Vitamin D requirements year round. Unfortunately, there is far more to it: it depends on where you live, the time of year and even your skin type or whether you are wearing sunscreen. The NCBI (The National Center for Biotechnology Information) has determined for example, that “exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin.”(1)

Simply put, if you live anywhere cold or rainy in the winter, you will have to supplement at least to some extent, and depending on your lifestyle, possibly year round irrespective of where you live.

Can I get my Vitamin D from my diet?

Yes, but not in significant amounts. There are only a few naturally occurring food sources of vitamin D. These include fatty fish, fish liver oil, and egg yolk. Cod liver oil is the densest nutrient source available at a reasonable cost.



Some foods are fortified with vitamin D, with vitamin D2 and D3. Cow’s milk is widely fortified as are other processed foods. Vitamin D fortification in developed countries was undertaken as an inexpensive and effective way to prevent “Rickets” which is a serious disorder of bone development mainly found in children, especially those who are desperately poor.

See our article: Dietary Sources of Vitamin D.

What is the Difference Between Vitamin D2 and Vitamin D3?

Vitamin D3 (cholecalciferol) is a natural by-product of animal origin that is created from exposure to the sun, while vitamin D2 (ergocalciferol) is a synthetic by-product of plant origin.

Even though there are similarities between Vitamin D2 and D3, vitamin D3 is more readily absorbed and utilized by the human body. There is no reason to supplement with Vitamin D2 (2) although unfortunately it is still used to fortify food. In Canada milk is fortified with vitamin D3, and while optional, nearly all milk sold in the U.S. is also fortified with vitamin D3.

How do I Know What my Vitamin D Levels Are?

Fortunately, there is a relatively simple blood test that measures serum concentration of 25 hydroxyvitamin D, the active form of vitamin D in the liver. This test is the best way to determine someone’s vitamin D levels and reflects the total amount of vitamin D from food, supplements and sun exposure.

How Much Vitamin D do I Need to Take?

There is no clear consensus as to the required amount. To start with, each body is unique and processes vitamin D differently. To further complicate matters, away from the equator UVB levels in sunlight are too weak, for 4-6 months of the year, to make any significant amount of vitamin D naturally.

The “official answer” comes from the US Institute of Medicine (IOM) which was asked by the Canadian and US governments to assess the current data on health outcomes associated with calcium and vitamin D, as well as updating the nutrient reference values, known as Dietary Reference Intakes (DRIs).(3)

In 2010 the IOM produced a report with recommendations largely aimed at bone health which calls for 600 IU of vitamin D daily for all ages up to age 70 and 800 IU after age 71. This assumes a limited amount of sun exposure. The report declared a safe upper limit of 4,000 IU daily for those above 9 years of age and a safe upper limit of 1,000 to 3,000 IU per day for children depending on age.(3) These recommendation are generally accepted, with some authorities recommending slightly higher levels. The Vitamin D council–a nonprofit research group– recommends 5,000 IU daily

How Much Vitamin D Should I Have in my Body?

The answer to this question is controversial because research concludes that the official recommended levels are far too low. According to the IOM, vitamin D level of 50 nmol/l (20 ng/ml) is sufficient for 97.5 percent of the population and the maximum level ought not to exceed 125 nmol/L (50 ng/mL).(3)

This recommendation is at odds with the research. In 2009 two double blind studies concluded that 50 nmol/l (20 ng/ml) was insufficient for fracture or fall reduction. (4) (5) In addition, a very large population based analysis found that bone density increased with higher levels far beyond 50 nmol/l (20 ng/ml) in younger and older adults.(6)

The ideal blood level of vitamin D that The Vitamin D Council recommends is 125 nmol/i (50 ng/ml).(7)

According to the The National Center for Biotechnology Information (NCBI) the desirable blood level of Vitamin D is between 90-120 nmol/l (36-48 ng/ml). (8)

A study in 2010 by Dr. William Grant estimated that if Canadians raised their vitamin D blood levels to105 nmol/L (42 ng/mg) it would prevent 37,000 deaths and save $14B in associated healthcare costs.(9)

Can I Take Too Much Vitamin D?

Vitamins are classified as either fat soluble (vitamins A, D, E and K) or water soluble (vitamins B and C). Fat soluble vitamins, once they have been stored in tissues in the body, tend to remain there.

Although fairly rare, you can take too much vitamin D. Excessive amounts of this vitamin will pull too much calcium into the bloodstream, ultimately leading to a disease called hypercalcemia, which can cause calcium deposits in the joints, and calcification of the arteries. Other symptoms of hypercalcemia include muscle weakness, joint pain, confusion, loss of appetite, constipation, abnormal heart rhythm, and even kidney stones.

On the bright side, it would appear that it is nearly impossible to get too much vitamin D from sunlight. This makes sense because the form of vitamin D that we get from the sun is “inactive,” and is stored in the skin and liver until the body activates it, based on its needs. Therefore the body activates only as much it needs, which means that the levels of vitamin D from sun exposure should be the optimal levels, more on that later.Going-to-the-Sun_Road_construction_crew_paving_around_milepost_33-300x200

Nearly all vitamin D overdoses come from supplements or foods, and even those overdoses are extremely rare. Recent studies suggest that healthy adults can tolerate more than 10,000 IU of vitamin D per day.(10)

Vitamin D Co-Factors?

Even more good news: it would appear that vitamin D overdose is even less likely so long as its partners (co-factors) vitamin A and vitamin K2 are present in the body in sufficient quantities. It is now believed by some experts that vitamin D toxicity, when it does occur, may in fact be due to a lack of vitamin A and vitamin K2. Interestingly, the inverse seems to hold true as well for vitamin A; its toxicity may come from taking high levels of vitamin A without adequate vitamin D and vitamin K2.  (11)

We believe that much can be learned from nature. When we consume vitamin D in the active form, from foods, it is most commonly found in liver (fish and mammals), where it occurs in combination with vitamin A. Where vitamin A creates compounds in the body that break down bone (osteoclasts), vitamin D creates compounds that reform bones (osteoblasts). Together they maintain the health and density of the skeletal structure.

When there is too much calcium in the blood, it is up to vitamin K2 to move it back into the skeletal structure. From this we can see that we need to look at vitamin D supplementation as part of a triumvirate that includes vitamins A and K2. By ensuring that we have adequate amounts of vitamins A and K2, it is far more likely that we can safely take higher doses of vitamin D.
Dr. Kate Rheaume-Bleue, a naturopathic physician, in her book, titled: Vitamin K2 and the Calcium Paradox: How a Little Known Vitamin Could Save Your Life, stated:

“We don’t see symptoms of vitamin D toxicity very often. But when we do, those symptoms are inappropriate calcification. That’s the symptom of vitamin D toxicity. And it is actually a lack of vitamin K2 that can cause that”.

Are Doses of Vitamin D Over 5,000 IU Safe?

There is no consensus due to the lack of credible large randomized controlled trials. Thankfully, there is currently underway a significant study at Brigham and Women’s Hospital, an affiliate of Harvard Medical School, in Boston, Massachusetts. This study, appropriately named VITAL, is an ongoing research study of 25,874 men and women across the U.S. investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (Omacor® fish oil, 1 gram) reduces the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. The results are expected in late 2017.(12)

Vitamin D is very widely researched. As of March 19, 2016, the total number of publications on the topic listed at was 66,891. This total compares to vitamin C at 55,646 and Vitamin E at 38,651.(13)

So even though there is a lack of large randomized studies, there is no shortage of papers and smaller studies to guide us.

For the moment the IOM remains the leading authority with regard to vitamin D recommendations.

How Controversial are the IOM’s Recommendations?

In 2015 researchers from the University of Edmonton published a paper which aimed to prove that the IOM made a calculation error in defining the vitamin D intake needed to reach and maintain 50 nmol/l (20 ng/mL). It is their contention that if the IOM had calculated it correctly, the RDA would have been ten times greater than what the IOM recommends.(14)

This conclusion was corroborated by Researchers from the University of California at San Diego and Creighton University in Omaha who claimed that their data confirmed the Institute of Medicine’s miscalculation as noted by the Canadian investigators. In a press release dated March 17, the American researchers stated that their work showed the current recommended daily intakes for vitamin D are only about one-tenth those needed to cut incidence of diseases related to vitamin D deficiency.(15)

What Does Evolutionary Anthropology Teach Us?images-3

It is generally accepted that humans evolved in the horn of Africa, close to the Equator over 30,000 years ago. Their days were spent out in the full sun, with little or no clothing. Their skin pigment evolved and protected them from sun burns and allowed the production of vitamin D through the skin. Living and working indoors, without sunshine exposure, is a relatively recent development.

In evolutionary terms it makes sense that people with darker pigmentation living in equatorial areas would have, as a general rule, optimal serum vitamin D levels. images-4

A very interesting 2012 study found that Massai pastoralists and Hadzabe hunter-gatherers have high serum vitamin D concentrations. The investigators measured serum 25(OH)D in 35 Massai and 25 Hadzabe and found that mean serum 25(OH)D levels were 47.7 ng/mL for the Massai, and 43.7 ng/mL for the Hadzabe. Even though the sample size was relatively small, it is significant that none of the participants was found to be vitamin D deficient. (study#16)

To get an idea of optimal vitamin D levels we can also look at studies that deal with outdoor workers to see what their levels are. As discussed earlier, vitamin D from the sun is stored in the skin and liver until the body activates it, based on its daily needs. Therefore the body activates only as much it needs, which means that levels from sun exposure should be the optimal levels.

Outdoimgres-3or workers in the tropics typically have high vitamin D levels ranging from 120 to 200 nmol/L (48 to 80 ng/ml).(17) By contrast, Statistics Canada reports that the average Canadian only has a vitamin D level of 68 nmol/L (27 ng/ml).(18)

Benefits of Higher Vitamin D Levels

Here is a summary of the health benefits that Dr. Holick, PhD., M.D., Boston University School of Medicine, believes could be achieved by raising the public’s vitamin D levels to 125 nmol/L:

  • Rickets, reduced by 100%
  • Osteomalacia, reduced by 100%
  • Cancers, all combined, reduced by 75%
  • Breast Cancer, reduced by 50%
  • Ovarian Cancer, reduced by 25%
  • Colon Cancer, reduced by 67%
  • Non-Hodgkins, reduced by 30%
  • Kidney Cancer, reduced by 67%
  • Endometrial Cancer, reduced by 35%
  • Type 1 Diabetes, reduced by 80%
  • Type 2 Diabetes, reduced by 50%
  • Fractures, all combined, reduced by 50%
  • Falls, women reduced by 72%
  • Multiple Sclerosis, reduced by 50%
  • Heart Attack, men, reduced by 50%
  • Peripheral Vascular Disease, reduced by 80%
  • Preeclampsia reduced by 50%
  • Caesarean Section, reduced by 75%

The list of health issues impacted by vitamin D continues to grow and includes health issues as diverse as asthma (19) and a good night’s sleep.(20)


Nearly every cell in the body uses vitamin D, and its health benefits range from reducing heart disease to boosting the immune system. It could be argued that the most important thing people can do to improve their overall health is to make sure they are getting enough of this vitamin to reach and maintain their optimal level. To that end, having a blood test is the only way to really know if you are getting enough vitamin D or not. Seasonal monitoring is also a good idea. For example, outdoor workers in low sunlight winter regions probably synthesize plenty in the summer, but not during the dark days of winter. Supplementation should be guided by how much Vitamin D people require and make use of over time because it varies as we age, change jobs, and move from place to place.