Vitamin D May Help Support Memory

Vitamin D is probably best known for its role in bone health. You need it to keep your bones strong. That’s because vitamin D helps your body absorb calcium — the foundation of strong, healthy bones. Vitamin D has a lot of other pretty important jobs. Without it, muscles can’t move and nerves can’t relay messages between the brain and the rest of the body. Your immune system can’t function without it, either. The powerful vitamin helps ward off harmful viruses and bacteria when they invade.

You can get vitamin D from some foods, including fatty fish such as salmon, tuna and mackerel. In smaller quantities, you’ll get it from beef liver, cheese and eggs. But these food sources aren’t enough to give adults the 600-800 international units (IU) of vitamin D they need every day. That’s why food manufacturers add it to most cow’s milk; many cereals; some orange juice; yogurt; and nondairy milks, such as soy and almond.

Your skin makes vitamin D when you expose it to direct sunlight — that is, without sunscreen and not through a window. You’ve got to be outdoors on a sunny day with uncovered skin. Given concerns about skin cancer, Americans don’t get a lot of direct sun exposure. But many doctors recommend that people over age 50 get 15 minutes three times a week on uncovered arms and legs. For those who live in places with long, dark winters, following this recommendation can be difficult.

Though supplements will help your body meet its daily vitamin D needs, there’s not enough evidence that they would have an impact on your brain health. That was the conclusion of a 2019 report from the Global Council on Brain Health, “The Real Deal on Brain Health Supplements.”

Some studies, though not all of them, suggest a possible connection between low levels of vitamin D and memory problems or dementia. In a study that followed almost 270,000 adults ages 55 to 69 for an average of 14 years, people who were deficient in vitamin D (measured via a blood test) were 25 percent more likely to develop all-cause dementia than those with normal levels. The results, published in The American Journal of Clinical Nutrition in 2024, found that people who regularly took vitamin D supplements lowered their risk of Alzheimer's disease by 17 percent. However, before doctors recommend any new habit, such as taking a vitamin pill, they must see repeated studies that include large groups of people and get the same results again and again. Researchers haven’t produced that level of support for taking vitamin D pills to help the brain.

Doctors often recommend vitamin D supplements to prevent osteoporosis in postmenopausal women, who are at an increased risk for brittle bones. Health care providers may also recommend supplements to people who have a diagnosed vitamin D deficiency. Older people, those with dark skin, people who are obese and people who don’t get sun exposure are more likely to lack healthy levels of the vitamin.