Do You Need to Supplement with Vitamin D?

Vitamin D foods

Table 1 below lists the content of the 40 most concentrated sources of vitamin D in real, non-fortified foods. Careful examination of this table makes it clear that, except for salmon or fresh tuna ⁽¹²⁾, it is difficult or even impossible to achieve recommended vitamin D intakes (600 I.U. or greater per day) ^{(10, 11)} with real, non-fortified foods.

Table 1. The 40 most concentrated sources of Vitamin D in real, non-fortified foods in the western diet.

At the top of the list for natural foods is cod liver oil, which at first appears to be a great source of vitamin D. It is, but unfortunately it also contains high levels of vitamin A which competes with our bodies’ metabolism for vitamin D and may impair vitamin D metabolism ⁽¹³⁾. A better choice is fish oil from the body of fish, rather than the liver. It also contains vitamin D and the healthful long chain omega 3 fatty acids (EPA and DHA) without the higher concentrations of vitamin A which may impair vitamin D metabolism ⁽¹³⁾.

But from an evolutionary perspective, fish oil whether derived from cod liver oil or only the body of fish, was known to have been consumed by the Vikings (circa 700s to 1100 AD) but was not commercially manufactured until relatively recent (200 – 300 years) times.

Accordingly, the Paleo Diet paradigm suggests that (as a species) if we consumed vitamin D from food, it must have come from other sources. Table 1 indicates that salmon is a concentrated source of vitamin D, and if we consume roughly ¼ pound of salmon or more per day ⁽¹²⁾, we may be able to achieve low level vitamin D balance. But who do you know who eats a quarter pound or more of salmon a day (day in and day out) in the 21st century?

As you move on down the list of foods in Table 1 from salmon, it becomes increasingly obvious that with our modern tastes and diets, few people could achieve vitamin D balance on any normal diets before modern, fortified foods (milk, margarine and processed foods) were introduced in about the 1930’s and 1940’s. Organ meats won’t do it, eggs won’t do it, shellfish won’t do it and meat won’t do it. The obvious implications of Table 1 is that food never was or never could have been the primary source of the hormone, vitamin D, which is essential for optimal human health. Before I leave this topic, let’s examine milk and dairy products.

Are dairy foods good sources of vitamin D?

To even suggest that milk is a good source of vitamin D is a total stretch of the facts. The Institute of Medicine Daily’s recommended intake for vitamin D is 600 IU per day for most people ⁽¹⁴⁾. Although this advice represents a substantial increase from previous estimates, it still falls far short of human experimental evidence showing that at least 2,000 IU per day is required to keep blood levels of vitamin D at the ideal concentration of 30 ng/ml ^{(6, 7, 10)}. See Table 2 below.

Table 2. Vitamin D Classifications in Blood.

An eight oz glass of raw milk (280 calories) straight from the cow without fortification gives you a paltry 3.6 IU of vitamin D. At this rate, you’d have to drink a ridiculous 167 eight oz glasses of milk just to achieve the 600 IU daily recommendation. Because most of the milk we drink is fortified with vitamin D, then an 8 oz glass typically yields 100 IU of this nutrient. However, even with fortification, you would have to drink six 8 oz glasses (1,680 calories or ~ 75 percent of your daily caloric intake) of milk to meet the daily requirement for vitamin D. If you wanted to reach the 2,000 IU level as suggested by the world’s best vitamin D researchers, you would have to drink 20 eight oz glasses of fortified milk amounting to 5,600 calories. No one in their right mind would drink 20 glasses of milk a day, even if they could.

As you can see from these simple calculations, whether fortified or raw, milk is an abysmal source of vitamin D. The best way to get your vitamin D is not by drinking milk, but rather by getting a little daily sun exposure as nature intended.

Sunlight exposure

Lifeguards and other outdoor workers can achieve blood concentrations that top out at about 60 ng/ml. But you really don’t need values this high. Most experts agree that values higher than 30 ng/ml will significantly reduce your risk for cancer and all of the other diseases associated with low vitamin D status ^(15-21). The good news is that daily sunlight exposure in the summertime for short periods 15-30 minutes will rapidly boost your blood levels of vitamin D above 30 ng/ml. Something that cannot be achieved with diet alone because almost all real foods, except salmon ⁽¹²⁾, that we commonly eat contain little or no vitamin D (Table 1).

Vitamin D supplementation

For most of us, regular sunlight exposure is a luxury that is difficult or impossible to come by on a year round basis. Obviously, our hunter gatherer ancestors, living at low to moderate latitudes did not have this problem. Consequently, you will need to supplement your diet with vitamin D3 capsules.

If we look at the official governmental recommendation for vitamin D intake (between 400 and 600 IU), however, it is unfortunately inadequate. The most recent human experiments show that blood levels of 30 ng/ml could never be achieved with vitamin intakes between 400 and 600 IU ^{(6, 7, 10, 11)}. In fact, a recent series of articles and reviews published in Nutrients actually demonstrated that the 600 IU recommendation was based on a misinterpretation of the data and was an order of magnitude too low. A meta-analysis of existing studies conservatively estimated daily needs of 1885, 2802 and 6235 IU for normal weight, overweight, and obese individuals respectively (22-24).

The majority of men, women and children in the U.S. maintain blood levels of vitamin D which are either deficient or insufficient ^(6-11). Hence, one of the best strategies you can take with adopting The Paleo Diet is to supplement daily with vitamin D3 if you are unable to get sunshine on a regular basis. Most vitamin D experts agree that daily supplementation of at least 2,000 IU of vitamin D3 daily is necessary to achieve healthful blood levels of 30 ng/ml or greater.

References:

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[22] Heaney, R., et al., Letter to Veugelers, P.J. and Ekwaru, J.P., A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients 2014, 6, 4472-4475; doi:10.3390/nu6104472. Nutrients, 2015. 7(3): p. 1688-1690.

[23] Veugelers, P.J. and J.P. Ekwaru, A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients, 2014. 6(10): p. 4472-4475.

[24] Veugelers, P.J., T.M. Pham, and J.P. Ekwaru, Optimal Vitamin D Supplementation Doses that Minimize the Risk for Both Low and High Serum 25-Hydroxyvitamin D Concentrations in the General Population. Nutrients, 2015. 7(12): p. 10189-10208.