Vitamin D is critical to all life forms. Most of us are familiar with the role of vitamin D in the regulation of calcium absorption, which is necessary for healthy bones and teeth. However, most people are unaware that vitamin D also aids in the absorption of other minerals essential to good health, such as magnesium for proper muscle function (including the heart) and optimum blood pressure, iron for the production of red blood cells and the utilization of oxygen, and zinc for stimulation of the immune system and the synthesis of DNA and RNA. More recently, research has demonstrated the role of vitamin D as a precursor for hormone production and as a powerful antioxidant.

So why are we talking about vitamin D now? Because natural UV sunlight is one of the main sources of vitamin D for the human body and our exposure to this valuable source is significantly diminished during the winter months. Actually, our bodies manufacture vitamin D from cholesterol (which is one of the reasons you don’t want blood cholesterol to be too low below 140 but that’s another article) when our skin is exposed to this UV light. There are other sources of vitamin D, which we will discuss later, but without adequate UV light for an extended period of time, there is a risk of vitamin D deficiency.

So the next logical question is how much do we need? According to the RDA, we need 200-400 IU daily. However, most of the recent information suggests that this recommendation is inadequate. In fact, the consensus among most holistic nutritional practitioners is that the daily requirement should be raised to 1,000 IU’s. Dr. Weston A. Price, who conducted the initial and most extensive research on human vitamin D requirements, suggested that we get at least 4,000 IU’s daily.

The other side of this issue is that of toxicity. How much is toxic? Yes, vitamin D like vitamin A is fat-soluble and we do need to be concerned about liver toxicity. However, the doses needed to result in toxicity have been exaggerated with the unfortunate result that many people are currently vitamin D deficient. One of the reasons the RDA is so low for vitamin D is that the government studies were conducted with synthetic supplements. Supplementing with synthetic forms of nutritional substances will invariably promote inadequate absorption, and thus toxicity. This also explains why the RDA figures have been notoriously low for several other micronutrients, such as vitamin C and vitamin E. Synthetic supplements are especially inferior for fat-soluble vitamins because of the toxicity issue. Another reason for inaccurate RDA recommendations is that they are typically based on uncontrolled or tainted studies. This is again another article.

Another factor to consider here is that vitamin D actually regulates the levels of calcium in the blood. Consequently, if there is not enough calcium in the diet vitamin D will cause it to be drawn from bone. In other words, someone with a calcium deficiency should not supplement with vitamin D. Similarly, people who are on low-fat diets should not supplement with vitamin D because adequate dietary fat is necessary for the assimilation of vitamin D. Any excess vitamin D (i.e., not assimilated by the body) will contribute to toxicity and even osteoporosis.

The message here is that vitamin D requirements are not clear-cut by any means. Like most other issues we discuss relating to health, each individual has different requirements.

Since the experts cannot agree on accurate vitamin D requirements, and since toxicity is such a real issue, especially with synthetic supplementation, our recommendation is that you get as much skin exposure to sunlight during the winter months as you can and that you eat foods that are naturally rich in vitamin D. This is not to say that you should stop taking your multivitamin. Everyone should be on a high quality multi like Bio-Multi Plus, which is available in our online store http://www.ingoodhealthinc.com. Foods that are rich in vitamin D are generally meats and eggs from animals raised in the wild or free-range animals. Some examples are wild salmon, free-range eggs, organic butter, oysters, and organ meats from wild or free range animals. Farm raised and caged animals are generally less healthy animals and therefore have significantly less of the healthy fat needed to retain fat-soluble micronutrients. They also tend to be deficient in the essential fats or have unhealthy ratios of the Omega 3 and Omega 6 fats. (For more on fats, go to http://www.westonaprice.org/facts_about_fats/facts_about_fats.html .)

Cow’s milk is generally a poor source of vitamin D and calcium for similar reasons. Most cows are raised on synthetic growth hormones and conventional feed that is laced with synthetic chemicals. In addition, much of the vitamins, minerals and essential enzymes in cow’s milk are lost during the homogenization and pasteurization processes. This is generally not an issue with raw milk. However, raw milk is not available in many states because of misguided government regulation.

The richest source of natural vitamin D is cod liver oil. Just two teaspoons of cod liver oil can supply 1,000 iu’s of vitamin D. This is generally safe as long as liver or kidney disease is not present and the diet contains adequate amounts of calcium, magnesium, and other minerals. The source of cod liver oil we recommend is Carlson’s. It is lemon flavored and less offensive than the straight stuff.

If you are still unsure about whether you need more vitamin D, you could have your blood tested for vitamin D status. For the reasons mentioned above, you may also want to have your blood levels of calcium, magnesium, potassium, zinc, and phosphorus tested.