After two years of work developing new guidelines to tell us how much vitamin D and calcium is enough, the Institute of Medicine released its report this week with the basic message: Relax, you’re all doing pretty well.

Yet confusion still reigns in headlines about the report, as there are several different facets to the new standards (and the reaction to them). The new report also seem to contradict earlier, alarming studies that found vitamin D deficiencies in most Americans. So, what’s going on?

Most people are doing just fine

IOM looked at both Vitamin D and calcium intake for different age groups, and slogged through hundreds of studies of the levels of those nutrients versus health. The only group that was found deficient was adolescent girls, whom the researchers said should intake a little bit more calcium.

The panel said its findings challenged the notion that, when it comes to dietary nutrients, “more is better” — a belief that has inspired a multibillion-dollar market for dietary supplements in the United States. Americans spent $1.2 billion last year on calcium supplements and $430 million on pills containing vitamin D, according to the Nutrition Business Journal. [Los Angeles Times]

Ohio State oncologist Steven K. Clinton, a coauthor of the report, says most people have enough variety in their normal diet to get adequate amounts of both nutrients.

New findings? Not convincing enough

The reason that gigantic supplement market exists is that a number of studies have suggested vitamin D—found in some foods but mostly produced in your skin by the action of ultraviolet radiation—could help to prevent diseases like cancer, heart disease, diabetes, and more. But in its meta-review of vitamin D studies, IOM wasn’t convinced. Its report reinforced the traditional wisdom that vitamin D is crucial for skeletal health, but wouldn’t go further in determining healthy levels.

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People fighting off winter colds and bouts of the flu typically reach for a glass vitamin C-packed orange juice, but new research suggests that vitamin D may be a better protector. People with low levels of the vitamin, which is often called the sunshine vitamin because sun exposure triggers its production in the body, are more likely to catch colds, the flu, and even pneumonia, a broad new study reports. The effect was magnified in people with asthma or other lung diseases.

Vitamin D deficiency is quite common in the United States — particularly in winter…. “People think that if they have a good, balanced diet that they will get enough vitamin D, and that’s actually not true,” said Dr. Michal Melamed…. “Unless you eat a lot of fish and drink a lot of milk, you can’t get enough vitamin D from diet” [CNN].

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The news just keeps getting better about vitamin D. Earlier this year, studies linked proper levels of the “sunshine vitamin” to a decreased risk of diabetes, heart attacks, and cancer; that’s in addition to the previously understood role that vitamin D plays in keeping bones strong. Building on all these findings, a new study suggests that maintaining proper levels of the nutrient can even stave off death from heart attacks and other causes.

Researchers point out that they haven’t yet demonstrated a causal relationship, just a connection. The study’s lead author, Dr. Harald Dobnig of the Medical University of Graz in Austria, said the results don’t prove that low levels of vitamin D are harmful “but the evidence is just becoming overwhelming at this point” [AP]. Researchers aren’t sure what the connection is but they speculate that the nutrient may play a role in regulating the immune system, and may also have an anti-inflammatory function that keeps the heart healthy.

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For decades, doctors have warned the public about the dire risks of too much sunbathing and ultraviolet radiation, and the public has responded by slathering on sunblock. Now, medical advice is swinging back in the other direction.

A host of new studies have indicated that vitamin D, which is produced by the body when exposed to the sun’s ultraviolet rays, helps reduce the risk of heart disease, cancer, diabetes, and other diseases.

The latest study followed over 18,000 men and found that men with vitamin D deficiency were more than twice as likely to have a heart attack than those with normal levels of the nutrient. They were also more likely to die as a result of heart disease. The study was published in the Archives of Internal Medicine [subscription required].

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After years of hectoring new parents about the need to keep babies protected from the sun’s fierce ultraviolet rays, doctors may be about to swing back the other way. A new study shows that many infants and toddlers aren’t getting enough Vitamin D, which is produced in human skin during exposure to sunshine.

Vitamin D is essential for bone growth and absorption of calcium in the digestive tract, and also plays a role in regulating the immune system. But doctors disagree on the severity of the problem posed by the low vitamin D levels found in the study, and are also divided on what course of action to recommend.

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