Vitamin D deficiency is the latest hot topic in the nutrition and health world. Very few foods naturally contain Vitamin D: salmon, tuna, mackerel and fish oils are the best sources. Vitamin D is also added to milk, and sometimes yogurt, orange juice, or cold breakfast cereals. We used to be more concerned about getting too much Vitamin D, because it’s known to be toxic at high levels.
However, there’s been a wealth of research in the past few years that makes many scientists believe the vast majority of us don’t get enough Vitamin D. Sun exposure to bare skin allows our body to manufacture Vitamin D. But guess what? If you live north of Boston, your body can’t make Vitamin D from November through February. You have to live south of a line drawn between LA and Columbia, SC for your body to manufacture Vitamin D year round. Cloud cover reduces the UV rays necessary to produce Vitamin D by 50%, shade (and pollution) by 60%, and sunscreen with an SPF of 8 or above blocks it completely.
Why the concern? Low levels of Vitamin D have long been linked with osteoporosis, which is why Vitamin D is typically added to calcium supplements. Newer research links low levels of Vitamin D with some types of cancer, especially colon, prostate, and breast cancer. There’s also interest in the role of Vitamin D in developing both type 1 and type 2 diabetes, multiple sclerosis, and high blood pressure.
Last week my husband had his yearly physical, and he asked his doctor to test his Vitamin D levels. He’s on the low side of normal, and has started taking a Vitamin D supplement. Since we live in Vermont, north of Boston, and he was tested the beginning of September, his Vitamin D levels are most likely at their highest right now. Taking a supplement seems like a prudent step.
There’s no way of estimating your Vitamin D levels. While people who spend much of their time indoors are at higher risk, it’s also not uncommon for people who spend a lot of time in the sun to have low Vitamin D levels. Here’s my suggestion: ask your doctor to check your Vitamin D levels, and then follow her suggestions for a supplement if necessary. Since Vitamin D can be toxic if you get too much from supplements or cod liver oil, it’s best to know exactly where you stand and to heed your physician’s advice.