nutrient review

Vitamin D Is For Cancer Defense

by Bill Sardi

From time to time news reports surface about a "cancer cluster" among workers in a building. Often the workers have been assigned to dark basement offices or sealed clean-rooms where they must wear space-suit like garb. After an indoor environmental examination, investigators often are unable to correlate any factor in the building with the cancer cases. But what if, rather than a cancer-causing agent, the cancer cases are attributable to a missing protective factor? Given a growing body of evidence linking cancer with vitamin D deficiency, a question surfaces: Are indoor workers getting sufficient sunlight to make enough vitamin D to protect them from cancer?

Vitamin D is formed in the skin of animals and humans by the action of short-wave ultraviolet light, the so-called fast-tanning sun rays. Precursors of vitamin D in the skin are converted into cholecalciferol, a weak form of vitamin D3, which is then transported to the liver and kidneys where enzymes convert it to 1,25-dihydroxycholecalciferol, the more potent form of vitamin D3.

Fat-soluble vitamin D supplements are available in two forms. Vitamin D3 is believed to exhibit the most potent cancer- inhibiting properties and is the preferred form of the vitamin. More than 10 substances belong to a group of steroid compounds that exhibit vitamin D activity. Vitamin D2 (ergocalciferol), derived from plants and yeast, is a form of the vitamin commonly added to milk and some nutritional supplements. The first vitamin D to be discovered was a crude mixture called vitamin D1; it is not available as a supplement.

Although the list of vitamin-D-rich foods is limited, it is acquired from foods such as egg yolks, butter, cod liver oil and from cold-water fish such as salmon, herring and mackerel.