How important is Vitamin D to your immune system and function?

Vitamin D helps regulate the immune system and the neuromuscular system. Vitamin D also plays major roles in the life cycle of human cells. Vitamin D is so important that your body makes it by itself — but only after skin exposure to sufficient sunlight.

What is vitamin D?

Vitamin D is a fat-soluble vitamin that primarily aids calcium absorption, promoting growth and mineralization of your bones. It’s also involved in various functions of your immune, digestive, circulatory, and nervous systems (1Trusted Source).

Emerging research suggests that vitamin D may help prevent a variety of illnesses, such as depression, diabetes, cancer, and heart disease. However, vitamin D’s relationship to these conditions is still poorly understood (1Trusted Source).

How much do you need?

There is significant debate within the scientific community about how much vitamin D your body needs.

While the U.S. National Academy of Medicine considers 600–800 IU of daily vitamin D to be sufficient for the majority of the population, the U.S. Endocrine Society recommends 1,500–2,000 IU per day

The Reference Daily Intake (RDI) is currently set at 600-800 IU of vitamin D for adults, based on the U.S. National Academy of Medicine’s recommendations

The optimal blood level of vitamin D is not concretely established but likely falls between 20 and 50 ng/ml

The U.S. National Academy of Medicine further suggests that a daily intake up to 4,000 IU of vitamin D per day is safe for most people, although much higher doses may be temporarily necessary in order to raise blood levels in some individuals

Although toxicity is rare, it is best to avoid long-term vitamin D doses in excess of 4,000 IU without supervision from a qualified healthcare professional.

SUMMARY

Vitamin D is necessary for calcium absorption and bone health. While there is no set guidance, dosage recommendations range from 600–2,000 IU per day — but some people may need heavier doses to reach and maintain healthy blood levels.

1. Spend time in sunlight

Vitamin D is often referred to as “the sunshine vitamin” because the sun is one of the best sources of this nutrient.

Your skin hosts a type of cholesterol that functions as a precursor to vitamin D. When this compound is exposed to UV-B radiation from the sun, it becomes vitamin D.

In fact, sun-derived vitamin D may circulate for twice as long as vitamin D from food or supplements

However, the amount of vitamin D your body can make depends on several variables.

Skin tone and age

People with darker skin need to spend more time in the sun to produce vitamin D than those with lighter skin. That’s because darker skin has more melanin, a compound that can inhibit vitamin D production

Age can have an impact as well. As you get older, vitamin D production in your skin becomes less efficient

Geographical location and season

The closer you live to the equator, the more vitamin D you’ll be able to produce year-round because of your physical proximity to the sun’s rays.

Conversely, your opportunities for adequate sun exposure decreases proportionally the farther away from the equator you live

Sunscreen and clothing

Certain types of clothing and sunscreen can hinder — if not completely block — vitamin D production

While it’s vital to protect yourself from skin cancer by avoiding overexposure to sunlight, it takes very little unprotected sun exposure for your body to start producing vitamin D.

Although there’s no official recommendation, sources suggest that as few as 8–15 minutes of exposure is enough to make plenty of vitamin D for lighter-skinned individuals. Those with darker skin may need more time (10).

SUMMARY

Your skin can produce large quantities of vitamin D on its own when exposed to the sun’s UV-B rays. However, many factors affect this process.