We may live in the Sunshine State, but some of us are still deficient in the "sunshine vitamin": vitamin D. Around the world, about 1 billion people are vitamin D deficient, and they are found in both sunny and rainy climates, according to the National Institute of Health. And that's a problem, because vitamin D is crucial for bone strength, immune support and disease prevention.

Your body produces vitamin D when you absorb the sun's rays through the skin. However, a number of us are spending more daylight hours indoors these days, and while you can get vitamin D through food, malabsorption and other issues can lead to an insufficient amount in the body.

Why do we need this vitamin, and what are some ways increase our vitamin D production? Sources from the National Institute of Health, University of Florida and Harvard Health explain.

How much vitamin D should you have in your body?

The National Institute of Health recommends 400-800 International Units depending on your age and weight. In 2015-2016, an analysis by the institute found that men and women have less than half of the recommended amount: 204 International Units for men and 168 for women.

People who take supplements boosted their overall intake from food and supplements to about 796 International Units per day. This is promising for those who choose to take a supplement, because it shows it is being absorbed by the body.

How much can you get from the sun?

When sunlight hits the skin, it is absorbed and converted into an active form of vitamin D, vitamin D3 or a chemical called calciferol. From there, it is used for essential bodily functions.

"Some experts have suggested that a few minutes of sunlight directly on the skin of your face, arms, back or legs (without sunscreen) every day can produce the body's requirement of vitamin D," according to an article published by University of Florida Health. "However, the amount of vitamin D produced by sunlight exposure can vary from person to person."

Having darker-colored skin can cut down the amount of vitamin D the skin makes, meaning you may need to spend more time in the sun. However, because overexposure to sunlight can be a risk for skin cancer, no more than a few minutes without sunscreen is recommended.

"The skin produces vitamin D that can last at least twice as long as the vitamin D you take through foods or supplements," writes Dr. Emily Ruiz in an article for Harvard Health.

How much do you get from food?

While sun exposure seems to be the best way to get vitamin D, there are some foods that naturally offer a sufficient amount. Try incorporating fatty fish like salmon, tuna and mackerel; foods fortified with vitamin D like dairy products, non-dairy milks and whole grain cereal; beef liver; and egg yolks.

How much can you get from supplements?

The vitamin D found in supplements comes in two different forms: D2 (ergocalciferol) and D3 (cholecalciferol). Both can be found in quantities up to 1,000 International Units. However, it is best to speak with your primary care physician first to receive blood testing and determine how much your body needs per day.

It is possible to get too much vitamin D. Vitamin D toxicity can occur when you take large doses of supplements. Side effects include nausea, vomiting, weakness and frequent urination, and it might also worsen bone pain and kidney problems, like kidney stones. This is why Harvard Health's Ruiz suggests supplements are most needed for those at risk of deficiency, like breast-fed infants, older adults, people with limited sun exposure, darker-skinned individuals and those who are overweight.

What are the benefits of vitamin D?

Stronger bones, teeth and nails are a result of the larger amounts of calcium absorbed because of vitamin D. It can also reduce blood pressure and risk for heart disease and cancer.

You will also have a boost in immune support. Some studies have shown that vitamin D deficiency could increase your risk of contracting Covid-19.

There are also mental health benefits to getting sufficient amounts of vitamin D. Studies have shown a reduction in symptoms of depression and anxiety.

"Vitamin D is involved in various brain processes, and vitamin D receptors are present on neurons and glia in areas of the brain thought to be involved in the pathophysiology of depression," according to an article published by the National Institute of Health.