Getting enough vitamin D is important for typical growth and development of bones and teeth, as well as improved resistance to certain diseases.
Here is more information about the benefits of vitamin D, plus information about downsides, how much you need, and foods with vitamin D.
Your body produces vitamin D naturally when it’s directly exposed to sunlight. You can also get vitamin D from certain foods and supplements to ensure adequate levels of the vitamin in your blood.
Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorus and facilitating normal immune system function 
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). A 2018 review of population-based studies found that low levels of vitamin D are linked with an increased risk of 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. But it’s unclear whether vitamin D deficiency contributes to heart disease or simply indicates poor health when you have a chronic condition
•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 IBS.
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 
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.
Vitamin D deficiency
Several factors can affect your ability to get adequate vitamin D from sunlight alone.
You may be less likely to absorb enough vitamin D from the sun if you 
•live in an area with high pollution
•use sunscreen
•spend most of your time indoors
•live in a big city where buildings block sunlight
•have darker skin (The higher the levels of melanin, the less vitamin D your skin can absorb.)
These factors can increase your risk of vitamin D deficiency. That’s why it’s important to get some of your vitamin D from non-sunlight sources.
The symptoms of a vitamin D deficiency in adults may include
•tiredness, aches, and pains
•severe boneor muscle pain or weakness
•stress fractures, especially in your legs, pelvis, and hips
A healthcare professional can diagnose a vit. D deficiency by performing a simple blood test. If you have a deficiency, your doctor may order X-rays to check the strength of your bones.
Some food sources of vitamin D
Some foods contain vitamin D naturally, and others are fortified with it. You can find vitamin D in the following foods 
•canned tuna
•cod liver oil
•beef liver
•egg yolk
•regular mushrooms and those treated with ultraviolet light
•milk (fortified)
•certain cereals and oatmeals (fortified)
•yogurt (fortified)
•orange juice (fortified)
It can be hard to get enough vitamin D each day through sun exposure and food alone, so taking vitamin D supplements could help;
There has been some debate over the amount of vit D required for optimal functioning. Recent studies indicate that we need more vitamin D than previously thought. The recommended dietary allowances for vitamin D are as follows depending on sun exposures ( should be higher doses in fall and winter 
•infants (0–12 months): 10 mcg (400 IU)
•children and teens: 15 mcg (600 IU)
•adults ages 18–70: 15 mcg (600-1000 IU)
•adults over age 70: 20 mcg (800-1200 IU)
•pregnant or breastfeeding women: 15 mcg (600-1000 IU)
Coach Eve