Vitamin D plays a crucial role in calcium absorption and bone health. Because we get most of our vitamin D from the sun, many people develop an insufficiency in the colder months. For older women at risk for osteoporosis, it is vital to ensure you are getting enough of this nutrient.
In this Q&A, Christopher Anthony Gold, DO, Assistant Professor, Medicine (General Internal Medicine), Icahn School of Medicine at Mount Sinai, explains why vitamin D is important and how to make sure you are getting enough.
Why is vitamin D important?
Vitamin D helps calcium absorb into your bones, which keeps them strong and healthy. This prevents bone diseases like osteoporosis, especially in menopausal and postmenopausal women. Vitamin D plays other important roles, such as assisting with your immune system and muscle function, and protecting the brain and central nervous system. It has some anti-inflammatory effects, and there is some small evidence that suggests high levels of vitamin D may decrease your risk for insulin resistance, potentially decreasing your risk for prediabetes or diabetes.
How much vitamin D do I need?
Vitamin D deficiency is not as common in the United States, though some studies suggest up to 25 percent of certain patient populations can be deficient. Vitamin D insufficiency, however, is more common, and can be seen in up to 30-40 percent of the population in some studies. To prevent this, the National Academy of Medicine recommends getting at least 600 international units (IU), or 15 micrograms (mcg), a day for adults under age 70, and 800 for those over age 70, through sun exposure, food, and/or supplements. If you live in a region with less sunlight, you should get at least 600 and up to 1,000 IU (15-25 mcg) of vitamin D a day. Menopausal and postmenopausal women should aim for at least 800 IU (20 mcg) a day and should pair vitamin D with 1,000 to 1,200 milligrams of calcium.
Keep in mind that too much vitamin D can lead to toxicity, but this is rare. The safe upper limit is defined as 4,000 IU a day (100 mcg).
What causes vitamin D insufficiency?
Lack of sunlight is the main cause in most cases. It can also be caused by not getting enough vitamin D-rich foods and supplements, especially in the winter. Aging also increases your risk because your skin has more difficulty synthesizing vitamin D from sunlight as you get older. Certain medical conditions, such as obesity, also increase your risk.
What are the symptoms of vitamin D insufficiency and deficiency?
Many people with vitamin D insufficiency do not have any symptoms, but some people may experience muscle weakness, bone pain, and fatigue. These could be signs that you have developed a vitamin D deficiency, which leads to bone disorders.
- Get 600 to 1,000 IU/15-25 mcg of vitamin D a day (depending on your age, medical conditions, and region)
- Spend between 5-30 minutes a day in the sun between 10 am and 4 pm without sunscreen
- Eat vitamin D-rich foods like wild salmon and foods that are fortified
- Take vitamin D supplements
Who is most at risk?
Those most at risk include:
- Older people
- People with darker skin
- People who live in northern regions with less sunlight
- People with obesity
- People who spend a lot of time indoors
- People with certain medical conditions, such as osteoporosis, hyperparathyroidism, celiac disease, and inflammatory bowel disease
One serving of wild salmon meets the daily requirement of vitamin D for most adults under age 70
How can I make sure I’m getting enough vitamin D, especially in the winter?
The National Institutes of Health suggests getting 5-30 minutes of sun exposure a day between 10 am and 4 pm without sunscreen. Keep in mind that getting too much sun can damage your skin and increase your risk for skin cancer.
In terms of diet, there are foods that are naturally higher in vitamin D. These include fatty fish, such as salmon, tuna, and mackerel. One serving of wild salmon—about three and a half ounces—contains about 600 IU, or 15 mcg, of vitamin D, which meets the daily intake requirement for most adults under age 70. Other sources include mushrooms and eggs, especially in the yolks. Some foods are supplemented and fortified with vitamin D in the United States, including milk, orange juice, yogurts, and some cereals. In terms of supplements, vitamin D2 and D3 are both great. Some research suggests that vitamin D3 may be a little more beneficial.
What should I do if I suspect my vitamin D levels are low?
If you suspect you are insufficient in any nutrient, you should talk to your primary care provider.