NEW YORK, Dec 16: Vitamin D is a vital nutrient with a wide range of benefits. It aids in the absorption of calcium, which is crucial for maintaining strong bones and teeth, and helps prevent conditions like rickets in children and osteoporosis in adults, explains Nicholas Rush, a registered dietitian at Fay. "Vitamin D also supports a healthy immune system, regulates glucose metabolism, and helps reduce inflammation."

However, 35% of Americans are not getting enough vitamin D.

Several factors contribute to this deficiency, including insufficient sun exposure (since the body produces vitamin D when exposed to ultraviolet light), geographic location, age, and skin color. Vanessa Rissetto, a registered dietitian and CEO of Culina Health, explains that individuals with darker skin tones have a harder time synthesizing vitamin D from the sun. The National Library of Medicine highlights that elderly individuals, people with obesity, nursing home residents, and hospitalized patients are particularly at risk for vitamin D deficiency.

Before rushing to buy supplements or spending time in the sun without sunscreen, experts have important information about vitamin D.

Vitamin D: More than just bone health

While vitamin D is widely known for promoting bone health and preventing osteoporosis, it offers other essential benefits. According to the National Institutes of Health, vitamin D helps the immune system fight off viruses and bacteria, which is especially important during cold and flu season. Additionally, it plays a role in regulating blood sugar and managing mood. Research has found links between low vitamin D levels and an increased risk of depression.

The sun isn’t the only source of vitamin D

Before reaching for supplements, consider whether your diet is lacking in vitamin D. The sun isn't the only way to get this essential nutrient. "Fatty fish like salmon, tuna, and sardines are rich in vitamin D, while egg yolks, beef liver, and cheese contain smaller amounts," says Rush. Many foods are also fortified with vitamin D, including milk, plant-based milk alternatives, cereal, orange juice, and yogurt. "Checking the nutrition facts label is the easiest way to see if a food contains vitamin D," Rush adds.

More isn’t always better

While vitamin D is essential, too much of it can be harmful. Vitamin D toxicity, often caused by high-dose supplements, can lead to elevated calcium levels in the blood, known as hypercalcemia. "This can cause symptoms like nausea, vomiting, muscle weakness, confusion, and even kidney stones," explains Rush. In severe cases, vitamin D toxicity can result in kidney failure, heart problems, and, in rare cases, death.

The recommended daily intake of vitamin D is 600 international units (IU) for individuals aged 1 to 70 and 800 IU for adults over 70. "However, your doctor may recommend a higher dose if you have a deficiency," Rush says.

Take vitamin D with fat

As a fat-soluble vitamin, vitamin D is absorbed best when consumed with fat. "Having a snack with healthy fats, like avocado, nuts, or seeds, can help your body absorb the vitamin D supplement more effectively," Rush advises.

It’s also beneficial to ensure you're getting enough vitamin K, found in leafy greens, or consider taking a supplement that includes both vitamins D3 and K2. Vitamin K works with vitamin D to help distribute the calcium produced by vitamin D.

Sun exposure isn’t a free pass

While low vitamin D levels may tempt you to spend more time in the sun, research suggests that just five to 30 minutes of midday sun exposure several times a week is sufficient for most people to produce enough vitamin D. The ideal exposure time varies depending on factors like skin tone, the amount of skin exposed, time of day, season, and location.

Whether you spend five or 30 minutes in the sun, it’s important to use sunscreen. According to The Skin Cancer Foundation, "Clinical studies have never found that everyday sunscreen use leads to vitamin D insufficiency." In fact, studies show that people who use sunscreen daily can still maintain adequate vitamin D levels. This is because no sunscreen offers 100% protection from UV rays, meaning some rays will still reach your skin. "It’s crucial to protect your skin from sun damage to reduce the risk of skin cancer," Rush emphasizes.