How do humans get vitamin d from the sun

As people become more and more likely to spend the majority of their time indoors, vitamin D deficiency becomes more common. This deficiency leads to an enormous array of health issues, particularly to the bones and skin.

Sometimes called the sunshine vitamin due to the body’s ability to create vitamin D with exposure to sunlight, vitamin D occurs naturally in only a few foods, such as egg yolks and some fish. Occasionally, grain and dairy products are also fortified with vitamin D.

How Does Your Body Get Vitamin D?

Excepting vitamin supplements, the easiest way to get the amount of vitamin D your body needs is through direct sunlight. In other words, without wearing sunscreen.

This bare skin exposure is one of the reasons for the increase in vitamin D deficiency found in many patients. Most people recognize the dangers of skin cancer and either stay out of the sun or wear sunscreen when they’re out and about. You still need to protect yourself from skin cancer, but unless you doctor advises otherwise, 10 to 20 minutes per day in the direct sun does not cause harm.

If you cannot get the vitamin D you need through sunlight exposure, you can take a supplement. Talk to your doctor about how much vitamin D you need to meet the daily recommended dose, but the average recommendation is 600 IU (international unit). For patients with extreme deficiencies, the number may be much higher, up to 4,000 IU.

Vitamin D is one of the few vitamins not readily available through diet alone, as so few foods contain it. What’s more, those that do contain it in small amounts, making it nearly impossible to meet the daily requirement through diet alone. Therefore, the best ways to ensure you do not suffer vitamin D deficiency are direct sunlight and supplements.

How Skin Tone Affects Vitamin D

Melanin, the substance that creates darker skin, also protects your body against UVB exposure (i.e. direct sunlight and the exact thing your body needs to create vitamin D). The result is that the bodies of people with more melanin (translation: those who have darker skin) have more difficulty creating vitamin D. The result is that they need to spend more time in direct sunlight than people with lighter skin tones do.

The time difference can be significant. People with the lightest skin colors create vitamin D the fastest, as they have less melanin blocking UVB. These are the people who can spend as few as 10 minutes a day in direct sunlight (assuming it’s summer and they live in a warm climate; otherwise it may be as much as 20 minutes). Those with extremely dark skin, however, may require an hour or more of direct sunlight. Of course, the more skin you expose, the shorter amount of time you require. In any case, talk to your medical provider to learn your time requirements.

What Are the Symptoms and Risks of Vitamin D Deficiency?

Often, symptoms of vitamin D deficiency are quite mild. When noticed, they mainly consist of:

• Bone pain
• Chronic fatigue
• Frequent bone fractures
• Muddled thought processes
• Muscle weakness
• Soft or deformed bones

Though you may not notice any symptoms, that doesn’t mean that vitamin D deficiency doesn’t present serious health risks. These include:

• Children may develop severe asthma
• Immune system problems, raising your risk of infection
• Increased mortality from cardiovascular disease
• Insulin resistance, impacting your body’s ability to process sugar and increasing your risk of diabetes, multiple sclerosis, and glucose intolerance
• Osteoporosis, a condition that includes brittle bones that are more likely to fracture
• Reduced cognitive function
• Rickets, a bone disease that causes soft bones and skeletal deformities

What Are the Causes of Vitamin D Deficiency?

The main cause of vitamin D deficiency is a lack of direct sunlight. Humans, especially Americans, spend less time outdoors. Most people work indoors now, and many of our leisure pursuits occur in an indoor setting as well. What’s more, when we are outside, many people avoid the sun as much as possible. The result is the body not absorbing enough UVB rays to create the amount of vitamin D it requires.

In addition, getting the required amount of vitamin D from your diet is nearly impossible, especially for anyone following a strict vegan diet, as most foods containing vitamin D are animal-based. These include:

• Beef liver
• Egg yolks
• Fish and fish oil
• Fortified milk

Even if you eat all of these foods every day, your odds of getting enough vitamin D are slim. For example, one egg only has a little over 21 IU, around 3.5 percent of the recommended daily allowance. A cup of fortified milk does a little better, as it contains around 98 IU, 16.33 percent of the daily allowance. A serving of beef liver has such negligent amounts that the nutrition information doesn’t even list vitamin D. The same is true for fish.

Treatment for Vitamin D Deficiency

If you suspect you may have vitamin D deficiency, schedule an appointment with your doctor to be tested. Typically, this requires the 25-hydroxy vitamin D blood test.

If test results indicate a deficiency, treatment simply means taking a supplement. Your doctor may also prescribe more time in direct sunlight, if your health allows.

According to the Institute of Medicine, the recommended IU for vitamin D is 600 up to age 70 and 800 for those over 70. However, for those with vitamin D deficiency, your doctor may prescribe significantly higher doses, up to 4,000 IU per day.

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How fast does your body make vitamin D?

Is 20 minutes of sun a day good?