Getting enough vitamin D helps the growth and development of bones and teeth. It may also provide improved resistance to certain diseases.

Vitamin D has several important functions.

1. Vitamin D may fight disease

In addition to its primary benefits, research suggests that vitamin D may also play a role in:

  • Reducing the risk of multiple sclerosis (MS).
  • Decreasing the chance of heart disease. Low vitamin D levels have been linked to increased risk of heart diseases such as hypertension, heart failure, and stroke.
  • Reducing the likelihood of severe illnesses. Although studies are mixed, vitamin D may make severe flu and COVID-19 infections less likely. A recent review found that low vitamin D levels contribute to acute respiratory distress syndrome.
  • Supporting immune health. People who do not have adequate vitamin D levels might be at increased risk of infections and autoimmune diseases, such as rheumatoid arthritis, type 1 diabetes, and inflammatory bowel disease .
2. Vitamin D may regulate mood and reduce depression

Research has shown that vitamin D might play an important role in regulating mood and decreasing the risk of depression.

A review of 7,534 people found that those experiencing negative emotions who received vitamin D supplements noticed an improvement in symptoms. Vitamin D supplementation may help people with depression who also have a vitamin D deficiency .

Another study identified low vitamin D levels as a risk factor for more severe fibromyalgia symptoms, anxiety, and depression.

3. It might support weight loss

People with higher body weights have a greater chance of low vitamin D levels.

In one study, people with obesity who received vitamin D supplements in addition to following a weight loss diet plan lost more weight and fat mass than the members of the placebo group, who only followed the diet plan.

In an older study, people taking daily calcium and vitamin D supplements lost more weight than subjects taking a placebo supplement. The researchers suggest that the extra calcium and vitamin D may have had an appetite-suppressing effect .

What are the symptoms of vitamin D deficiency?

The symptoms of a vitamin D deficiency in adults may include :

  • tiredness, aches, and pains
  • severe bone or muscle pain or weakness
  • stress fractures, especially in your legs, pelvis, and hips