Government's Vitamin D recommendations are said to be 200 IUs a day up to age 50, 400 IUs to age 70, and 600 IUs over 70... some advocate for 2,000 IUs a day and even more.
In some parts of the country, 10 minutes of midday summer UV-B rays on exposed legs, arms and faces can make up to 10,000 IUs. No matter what our skin type is, the time of year, the latitude where we live, what we eat, let's face it: we all will be healthier if we get more not less outdoor activity, irrespective of whatever supplements we take.
Maybe some amount of supplementation is beneficial at some times. Just drinking fortified milk is taking supplements. But, we also should be aware of similar recommendations that did not prove to be healthy advice-- e.g., suggestions to take beta carotene and vitamin E proved to be dangerous:
From the
NYT-
In a study published in The New England Journal of Medicine in 1994, 29,000 Finnish men, all smokers, had been given daily vitamin E, beta carotene, both or a placebo. The study found that those who had taken beta carotene for five to eight years were more likely to die from lung cancer or heart disease.
Two years later the same journal published another study on vitamin supplements. In it, 18,000 people who were at an increased risk of lung cancer because of asbestos exposure or smoking received a combination of vitamin A and beta carotene, or a placebo. Investigators stopped the study when they found that the risk of death from lung cancer for those who took the vitamins was 46 percent higher.