When you think of ‘Prescription Strength’, most of us will think, somehow, that it is automatically better or stronger than a similar ‘Over the Counter’ variety. But with prescription vitamin D supplements, this is far from the case. In fact, these prescription vitamin D supplements are Completely inferior to the vitamin D3 supplements that you can buy in any health food store in many ways. They are less potent, have more potential for toxicity, don’t have the ‘active’ component that regular vitamin d does and they have a shorter shelf life. Do you STILL want prescription strength vitamin D?

Vitamin D has become somewhat famous lately, with tons of studies showing that millions of otherwise ‘healthy’ people are vitamin D deficient, in many cases SEVERELY so, and that the consequences are diseases like cancer, heart disease and multiple sclerosis. As clinicians become more aware of the problems associated with vitamin D deficiency, more are testing for and treating it. And while awareness of vitamin D is GREATl, it will also bring more prescription vitamin D supplements- which may NOT be so great.

The most common form of prescription vitamin D is in the form of Vitamin D2, also called Ergocalciferol. This is also the same type of vitamin D that is used for the ‘fortification’ of most milk and cereal products. But the ‘over the counter’ formulation of vitamin D in the form of Vitamin D3, also called Cholecalciferol, is far superior to the prescription formula that is routinely prescribed. First of all, prescription vitamin D is at least one-half as effective as vitamin D3 and possibly even up to one-tenth as effective. In ‘The case against ergocalciferol (vitamin D2) as a vitamin supplement’, the authors state, “50 000 IU vitamin D2 should be considered equivalent to 15000 IU vitamin D3, and likely closer to 5000 IU vitamin D3″. That’s One-Tenth as effective as vitamin d that you can buy in stores. When these differences were discovered in the 1950′s, Germany reformulated their prescription vitamin D to vitamin D3, but almost 60 years later, the United States is still using prescription vitamin D that doesn’t work.

And it really doesn’t work. One consequence of vitamin D deficiency is an increase in parathyroid hormone levels which alters calcium metabolism and preventing calcium from building bones. Studies measure the effectiveness of vitamin D treatment by measuring vitamin D levels increasing AND parathyroid hormone levels decreasing. In studies that compare the two different types of supplements, vitamin D3 supplements decreased parathyroid hormone while vitamin D2 didn’t. Another extremely important function of vitamin D, one that can’t be understated, is vitamin D’s ability to bind to ‘Vitamin D Receptors’ in the body. These receptors, also called VDR, are present in almost every tissue in the body and are one possible explanation for the extremely diverse health effects of the vitamin. When VDR’s are bound with an active form of vitamin D, it can help to prevent the expression of a mind boggling array of disease causing genes. Yet, vitamin D2 produces an active hormone that has 40% less binding ability to VDR’s than does the hormone produced from vitamin D3. This makes vitamin D2 much less ‘Biologically Active’ than a Vitamin D3 Supplement and leads to the possibility that prescription vitamin D doesn’t even prevent the diseases and problems that treatment of vitamin D deficiency is supposed to alleviate!

Another disadvantage of prescription vitamin D , is that it has a shorter half life in the body. Water soluble vitamins need to be replenished continually; for instance B vitamins and vitamin C are best metabolized in small doses throughout the day. But fat soluble vitamins like vitamin D do NOT need to be taken every day. In fact the half life of vitamin D3 supplements is 3 weeks. This means that 3 weeks after you take one dose, one half of that dose is still left in your body. This is true whether you get it from the sun, food or supplements. But prescription vitamin d has a much shorter half life, which means that you not only need more of the vitamin to prevent or treat deficiency, but you also need to take that higher dose more OFTEN.

But these higher doses could cause more problems. Researchers since the 1930′s have found higher potential for toxicity, more impurities and less consistent formulations in vitamin D2 preparations than in Vitamin D3 Supplements . In fact, researchers interpreting studies on vitamin D find that the studies done using vitamin D2 have less consistent results and recommend that all vitamin d research be done using vitamin D3 supplements for its more consistent results, better method of action in the body, lower toxicity levels and its improved shelf stability.

So while progress is being made in the awareness of the widespread problem of vitamin d deficiency, doctors who actually test for and treat vitamin D deficiency most often choose to ignore the advice of vitamin D researchers Dr’s Houghton and Vieth who state, “… vitamin D2, or ergocalciferol, should not be regarded as a nutrient suitable for supplementation…”. It seems that patients would be better served if their doctors, instead, recommend their patients go to the local health food store to treat their vitamin D deficiency.

Kerri Knox, RN- The Immune Health Queen
Functional Medicine Practitioner