VITAMIN D and calci-
You may have heard a bit about this news, and I want to tell you more and give you my take on what it means.
Scientists followed nearly 1,200 Nebraska women who were 55 or older. The women were randomly divided into three groups: one group took calcium supplements, another took calcium plus vitamin D and the third group took a placebo, or dummy pill.
Unexpectedly, scientists found that women taking calcium plus vitamin D for four years had much lower cancer rates than the other groups--more than four times lower. This applied to all kinds of cancers: breast, colon, lung, lymphoma, uterine and others.
The study is the first ever to show vitamin D supplements may reduce cancer risk. Scientists had long suspected this was the case but had been unable to prove it.
They had observed patterns showing that the farther people lived from the equator, the higher the rates of many cancers. The farther north you go in the United States, the less sunshine you are exposed to. Because sunlight on our skin produces vitamin D in the body, scientists wondered if vitamin D somehow protected against cancer.
However, only one other study looked at actually giving vitamin D supplements. That study, the Women's Health Initiative, gave the government-recommended 400 units of vitamin D daily and found no cancer protection.
The newer study, however, gave a much higher dose, 1,100 units of vitamin D-3,
Vitamin D overdoses are rare, but they are possible because the body stores extra vitamin D in fat cells. It doesn't purge unneeded
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It's hard to get enough vitamin D from foods; it's found in fatty fish, shiitake mushrooms and fortified milk. Mainly, the human body seems to have evolved to make vitamin D from a three-step chemical reaction caused when sunlight hits our skin.
After forming in the skin, vitamin D travels through the bloodstream and is transformed again in the liver and finally by the kidney. After these transformations, the magic begins.
Vitamin D helps the intestines absorb calcium from food and helps the bones become stronger. It's good for more than the bones. Tissues all over our bodies have receptors for vitamin D--skin, muscles, nerves, pancreas, thyroid and parathyroid, the immune system and even sperm cells.
Scientists don't yet understand how these body parts use vitamin D, but it's clear that they do. Recent studies have suggested that people with high intakes of vitamin D have lower rates of autoimmune problems and diabetes as well.
So with all the good things vitamin D can do, how can you get more?
the role of the sunSome experts recommend "sensible sun exposure," but this may not be enough in the northern U.S. for much of the year, plus there is the risk of sunburns and skin cancer if people overdo it.
How much vitamin D your skin makes depends on skin color, as well. Pigments that make skin darker acts as a natural sunscreen, blocking some ultraviolet light. Thus, darker-skinned people take longer to get a sunburn and to make vitamin D. Elderly folks also make vitamin D more slowly. Children are more vulnerable to sunburns.
So, it's hard to recommend sunbathing. Just for the record, though, 20 minutes on the beach would make about 10,000 units of vitamin D for some people.
No one recommends getting a sunburn. With sunbathing controversial, many experts are debating vitamin D supplements instead.
It may take a few more years of research to clarify exactly what is most helpful. But for now, it seems to me that it wouldn't hurt to take a standard multivitamin that has some vitamin D, possibly a little extra if your physician OKs it. Look for the best form of the vitamin: vitamin D-3, aka cholecalciferol.
Jennifer Motl welcomes reader questions via her Web site, bright eating.com, or mailed to Nutrition, The Free Lance-Star, 616 Amelia St., Fredericksburg, Va. 22401.| Jennifer Motl is a registered dietitian. Formerly of Fredericksburg, she now lives in Wisconsin. |