By Benjamin V. Treadwell, Ph.D.

For most of us, vitamins are synonymous with good health. Yet most Americans do not take vitamins. (See Research Update along side this article.) Changing diet affects the need for vitamins, as does age, since older bodies don't absorb vitamins as well as younger ones. Vitamin D is a good example of the controversy surrounding vitamins.

Vitamin D seems like a familiar friend. It's been added to milk and listed on our milk cartons for as long as many of us can remember. But if you think that Vitamin D has long been well understood, think again!

The Truth About Vitamin D

The "facts" surrounding vitamin D are in a state of flux. Strictly speaking, vitamin D is not a vitamin at all. By definition, a vitamin is a substance we require but cannot make in sufficient quantity for maximum health. Recently, scientists have come to understand that our bodies can synthesize all the D we require for full health, but only when conditions are right.

Our bodies synthesize a precursor form of the vitamin. It requires UV irradiation from the sun for conversion to vitamin D₂. This reaction occurs in our skin. Vitamin D₂ spontaneously rearranges its structure to produce vitamin D₃, the form present in our vitamin pill. Vitamin D₃ is modified to additional active forms by the liver, kidney and various tissues of the body, resulting in a range of biological activities.

Vitamin D Deficiency and Disease

Early humans lived largely in equatorial Africa, free of sun-blocking garments. They had plenty of sunlight to produce adequate levels of D. This changed when humans migrated to northern latitudes with less sunlight, more clothing and, consequently, less vitamin D synthesis. The decrease in exposure to sunlight was accentuated by the industrial revolution, when adults and children worked long hours indoors. These conditions produced rickets, a skeletal disease common to children in 17th century England. The deficiency in adults caused a related disorder, osteomalacia, or softening of the bones. It was learned later that adding fish or fish oil to the diet could prevent these diseases. The active component in fish oil was later identified as vitamin D3, and shown to be required for proper mineralization of the skeleton. Hence, it was labeled a vitamin, since it was believed we needed to obtain it from our diet.

Rickets was the first of many discoveries linking vitamin D deficiency with disease. Preliminary research has now implicated this vitamin in a host of common diseases, including osteoporosis, cardiovascular disease, muscle weakness, high blood pressure, diabetes, multiple sclerosis (MS), rheumatoid arthritis (RA), inflammatory bowel disease (IBD), Crohn's disease, and cancer.

Several of these diseases are attributed to vitamin D's regulatory action on the immune system. In animal models of autoimmune disease, especially MS, vitamin D has been demonstrated to virtually stop the progression of the disease. This effect is attributed to vitamin D's capacity to "reboot" the immune system and consequently to decrease inflammation by lowering the level of inflammatory cytokines and elevating the level of anti-inflammatory cytokines.

The story is not yet complete, however. The actual mechanism is sure to be more complex, since this vitamin is involved in the regulation of numerous genes. No fewer than 21 different types of tissues contain the vitamin D receptor and thus are somehow affected by vitamin D.

The vitamin may also have a role in prevention of prostate, colorectal and breast cancer. Studies have demonstrated a significant correlation between low plasma levels of D and increased incidence of cancer. Epidemiological studies have demonstrated an inverse correlation between the amount of exposure to sunlight and the incidence of MS, RA, prostate, and colorectal cancer. MS is virtually nonexistent in the equatorial regions of the world, and the incidence of this disease increases with latitude. The Eskimos, however, offer an exception. They have a low incidence of MS, but their diet is rich in fish and, therefore, vitamin D.

Significant evidence indicates the average American does not have an adequate amount of vitamin D (as determined by measuring plasma levels) for maximum health and prevention of disease. This is especially true of those over 50, as older skin does not function as well in the conversion of inactive to active vitamin D.

Others who have impaired D synthesis are those with dark skin, and many women who live in cultures in which clothing and veils cover their skin. Epidemiological data also show an increased incidence of prostate cancer in dark-skinned men. To produce an equivalent level of vitamin D, very black skin requires 6 times longer exposure to the sun than does very light skin.

How Much Is Optimal?

Currently, there is no established optimum level for vitamin D consumption. The only available guideline is the "reference daily intake," which is estimated from studies demonstrating the amount necessary to prevent such diseases as rickets and osteomalacia. This level is generally accepted as 400 IU/day, regardless of age, diet and other factors. However, many believe this level is much too low to produce an optimum vitamin D plasma level that is effective in preventing or attenuating the diseases listed above.

Interestingly, the amount of vitamin D synthesized by white human skin under intensive UV exposure (a level commonly produced by our outdoor ancestors) is equivalent to 4,000 IU/day, ten times the amount currently recommended. Recent investigations indicate that oral intake of this amount/day does not cause adverse effects. However, the upper limit for adults, as recommended by the US Standing Committee on the Scientific Evaluation of Dietary Reference Intakes (1997), is in the range of 2000 IU/day. This is a controversial number!

So how much should we take/day, if any? This question has no definitive answer just yet. The current recommended adult adequate intake level (400 IU/day) was set before we knew about the intricate details of vitamin D metabolism. Furthermore, the early recommendations were directed toward preventing the childhood disease of rickets, and not the numerous D-associated diseases, mentioned above, which at that time were largely thought to be unrelated to vitamin D.

The major danger from taking too much of the vitamin is developing hypercalcemia (elevated serum calcium), which can cause kidney stones and harm kidney tissue. However, this can be monitored by routine blood or urine analysis. The evidence indicates that the recommended 400 IU/day is probably too conservative for people over 50, and two to three times that amount may be closer to the target level.

Although the need for vitamins and minerals is widely recognized, most Americans don't bother to take supplements that would ensure adequate vitamin intake. A national survey by the Centers for Disease Control and Prevention produced data indicating that 60% of the U.S. population had not taken at least 1 vitamin or mineral in the past month.

Vitamin C is the most commonly consumed vitamin, followed by several B vitamins. Vitamin E is 7th, A is 8th and D is 9th on the list of the top ten most common ingredients. Folic acid, well known for its importance during pregnancy, is 10th.

Vitamin consumption correlates with age, education, gender and geography. The groups with the highest vitamin supplementation are those who are non-Hispanic whites, women, 50 and over, have 13+ years of education, and live in the West. For further information, click here.

This Research Update column highlights articles related to recent scientific inquiry into the process of human aging. It is not intended to promote any specific ingredient, regimen, or use and should not be construed as evidence of the safety, effectiveness, or intended uses of the Juvenon product. The Juvenon label should be consulted for intended uses and appropriate directions for use of the product.

QUESTION: I take the Juvenon energy pill and love it, but how do I know which are the right vitamins to take along with it?

Kim, via email

ANSWER: Most people do not consume the required amount of fruits and vegetables per day to meet the daily vitamin requirement. In addition, the elderly and those with genetic errors require more than the recommended daily intake.



It is a good idea to be on the safe side by taking a good multiple vitamin, like a Centrum® or a comparable substitute. If you are part of the majority of Americans who do not meet the specified daily veg-fruit intake, then I would also recommend taking one B-complex/day, which contains the B vitamins in significantly higher doses than most multiple vitamins.



The Juvenon formula works best with a fully tuned up body, one with sufficient vitamins to produce maximum metabolic efficiency and protection from toxic substances.

Send your questions to AskBen@juvenon.com.

For more questions and answers, go to juvenon.com/product/qa.htm.

Benjamin V. Treadwell, Ph.D., is a former Harvard Medical School associate professor and member of Juvenon's Scientific Advisory Board.