Getting adequate vitamin D in the fall and winter

Vitamin D plays a large role in overall health, but it can be challenging to absorb sufficient levels – especially in the colder months. A Baylor College of Medicine expert provides tips on how to maintain your vitamin D intake in the fall and winter. 

“Vitamin D is well known to support bone health, but it also plays a role in the health of your heart as well as your GI tract. It is tougher to get it because a lot of the absorption and how the vitamin gets transformed to a usable substance in our bodies is from the sun,” said Dr. Mike Ren, assistant professor in the Department of Family and Community Medicine at Baylor. “You need the sun high in the sky, not when it’s rising or about to set, for your body to effectively absorb sunlight to absorb the vitamin D.”

While some fatty fishes and seafood naturally contain some vitamin D, it is not commonly found in other foods, so people typically do not get enough vitamin D from their diet. Sun exposure helps, but in the fall and winter months when there might be less sunlight, people tend to be more deficient. The typical adult needs 800 international units of vitamin D per day, which roughly translates to 15 to 30 minutes of good, direct sunlight. There is no need to put on a bathing suit just to get sun. You can be fully clothed with the sun shining on your face or hands for sufficient exposure. Make sure to get your sun exposure during peak sunlight and not at sunrise or sunset. 

While some winters are very mild, others require you to fully cover up to keep warm, leaving little-to-no skin exposed to the sun. If you are fully dressed in winter gear covering your hands and face, you will not get the same level of UV and vitamin D absorption as someone spending time outside in a warmer climate. 

If you spend ample time inside, especially without windows, Ren recommends taking an over-the-counter vitamin D supplement. 

“If you take supplements, you need more than the recommended 800 international units per day because you're not going to absorb 100% of that supplement, so get 5000 international units as the baseline,” he said. “It’s a supplement, and it’s safe to take. If there is a little excess, your body will excrete it out.”

Vitamin D deficiency is prominent in people who spend a lot of time indoors and little time outdoors. A common side effect of weight loss surgeries such as gastric sleeve is the decrease of vitamin D absorption, so these individuals might need more supplements than the average person. People with cystic fibrosis or kidney and liver disease have absorption issues because those bodily functions normally help metabolize vitamin D. Ren suggests they should get their levels checked and consider further supplementation. 

Vitamin D is touted with calcium absorption and bone health, but recent studies also show links between vitamin D and heart health, as well as vitamin D and low cancer risk. 

“Some new studies are also finding that vitamin D is important for proper muscle function, like your constantly beating heart, as well as lower risk of getting a variety of cancers,” he said. “These are new studies so I don’t want to overestimate their importance, but on the flip side, I don’t want people to trivialize it and say it’s not important.”

Ren emphasizes the importance of getting your vitamin D levels checked.