You might need to up your vitamin D dosage in the winter months, and taking supplements or eating certain foods can help.
“The risk of deficiency can go up because you have no sunlight,” Marie van der Merwe, PhD, coordinator of the Applied Physiology and Nutrition doctoral program at the University of Memphis, told Health. “It becomes more pronounced in the wintertime.”
Vitamin D helps your body absorb calcium and, in doing so, helps prevent osteoporosis, which weakens the bones.
Additionally, vitamin D is needed for the nerves to send messages between the brain and the body, and it helps the immune system protect against viruses and bacteria. The nutrient also helps the muscles move; a deficiency can cause weak, painful muscles.
The recommended dietary allowance depends on your age:
- Infants under 12 months: 10 micrograms (mcg), or 400 international units (IU)
- People aged 1 to 70: 15 mcg, or 600 IU
- People aged 71 and older: 20 mcg, or 800 IU
It’s possible—but tricky—to get enough vitamin D through food alone.
“The problem with vitamin D is it’s really hard to get it from our diet because there’s not a lot of foods that have vitamin D in it,” van der Merwe said.
Fatty fish—such as trout, tuna, salmon, and mackerel—and fish liver oils are some of the best sources of vitamin D, while egg yolks, cheese, beef liver, and mushrooms have small amounts.
Additionally, many breakfast cereals are fortified with vitamin D, as are some milks, yogurts, and orange juices.
A Centers for Disease Control and Prevention (CDC) survey found that around 19% of adults take a vitamin D supplement.
Even though vitamin D deficiencies are common, you don’t necessarily need a supplement unless a doctor has recommended one, Pieter Cohen, MD, an associate professor of medicine at Harvard Medical School, told Health.
“It’s not something that people should feel obligated to take,” he said. “We do not recommend that healthy people [who have no evidence of a vitamin D deficiency] take vitamin D in the winter, even in Northern latitudes.”
If you already take a supplement, Cohen doesn’t recommend upping your dosage in the winter months, nor does he recommend starting a supplement to take only during the winter months.
However, he explained that it’s fine to add a vitamin D supplement into your everyday routine if you want to and will be sticking with the recommended dose.
“As long as you stick to the recommended daily amount, that’s totally safe—but that’s the key,” Cohen said.
It is possible to get too much vitamin D; vitamin D toxicity can cause drowsiness, confusion, abdominal pain, vomiting, and weakness. If the symptoms progress, the condition can include confusion, agitation, and even coma.
