Four important reasons to get enough vitamin D
Vitamin D3 plays an important role in the strength of your bones. It also bolsters your immune system and supports mental well-being.
You get this essential vitamin from seafood, eggs, mushrooms and fortified foods.
You can also get plenty of vitamin D3 simply by stepping outside — your body synthesizes this vitamin when your skin is exposed to sunlight.
Here are some benefits of vitamin D, along with how much you need and when to supplement.
Vitamin D3 and its counterpart, D2, are both forms of vitamin D. Vitamin D2 is found in plant sources, mushrooms and yeast, and supplements
Vitamin D3 is found in animal products and produced by your body from sunlight. Both types of vitamin D provide the same benefits and contribute to your overall vitamin D level.
That said, when it comes to selecting a supplement, you'll always want to choose D3 over D2.
Vitamin D3 is easier for the body to absorb, so it raises your vitamin D levels more effectively, says Taylor Moree, a registered dietician at The Nutrition Clinic for Digestive Health.
Vitamin D has multiple positive effects on your physical and mental health, including:
Supporting healthy bones
Vitamin D helps your body absorb calcium and phosphorus — both of which promote bone health. Vitamin D also regulates and stimulates osteoblasts, the cells responsible for bone formation.
Without adequate vitamin D, you wouldn't be able to absorb enough calcium to maintain your bone density, and calcium deficiency may raise your risk of osteopenia and osteoporosis.
A lack of vitamin D can also lead to rickets, a condition that causes weakening and softening bones in children.
Studies have linked low levels of vitamin D to depression, though the exact link between vitamin D and depression remains unclear.
Simply put, experts don't know whether low levels of vitamin D directly contribute to depression — or if certain factors, like a lack of sunlight or a diet that lacks key nutrients, independently contribute to both depression and vitamin D deficiency.
That said, some research does suggest vitamin D supplements may help ease depression. A 2019 review analyzed 4 studies with a total of 948 participants who had depression and concluded that vitamin D supplements had a moderate effect on reducing depression symptoms.
However, results from other studies on vitamin D and depression are mixed, with some research suggesting vitamin D supplements do little to improve depression symptoms.
Future research may help shed more light on the connection between vitamin D and depression and the potential benefits of supplements.
Regulating the immune system
Vitamin D supports your immune system by regulating B and T cell production — the cells that eliminate pathogens — and by supporting cells that fight off bacteria and fungi.
More research is needed, but taking a vitamin D supplement could offer some protection during flu season by lowering your risk of upper respiratory infections.
Vitamin D may also play a part in autoimmune disease, conditions where your immune system becomes overactive and attacks your body.
Experts have linked low levels of vitamin D to both onset and progression of multiple sclerosis, lupus, rheumatoid arthritis, type one diabetes and inflammatory bowel disease.
On the flip side, vitamin D supplements may help lower your risk of these conditions.
A large study from 2019 monitored 25,871 people over the course of five years. In that time, some took vitamin D supplements with or without fish oil, some took fish oil only, and some took a placebo. The participants who took vitamin D had a 22% reduced rate of autoimmune disease after five years, compared to the placebo group.
It may lower your risk of cancer
Some research suggests low levels of vitamin D may increase your risk of cancer. Other research suggests you're less likely to die from cancer if you have high vitamin D levels.
The role of vitamin D and cancer has been studied most often in colorectal, breast, prostate, and pancreatic cancer. Research suggests vitamin D may offer some protective benefits for each of these types of cancer, with colorectal cancer having the strongest evidence base.
However, not all studies agree. Experts have found conflicting evidence for how much vitamin D might influence cancer, so further research may yield more insight.
How much vitamin D3 do you need daily?
An estimated 40% of adults in the US and about 15% of children have a vitamin D deficiency.
It can be difficult to get enough vitamin D from food, especially if you eat a vegan diet, have allergies to foods that contain high amounts of vitamin D and have a health condition that affects your body's ability to absorb vitamin D.
But spending time in bright sunlight three days a week, with your arms and legs exposed, is typically enough to help you avoid vitamin D deficiency. You'll need to spend about 15 minutes in the sun at a time if you have light skin and about 25 minutes if you have darker skin.
Can you get too much vitamin D3?
Vitamin D is a fat-soluble vitamin — these types of vitamins remain in your body, in fatty tissue and in your liver.
Because your body stores vitamin D, you can consume too much of it. Daily doses that exceed 50,000 IU — more than 80 times the RDA — may cause hypercalcemia, a buildup of calcium in the body.
Hypercalcemia can cause nausea and vomiting, loss of appetite, excessive thirst, muscle weakness, pain, dehydration and kidney stones.