A Guide to Vitamin D

Vitamin D deficiency is a major unrecognized health problem all over the world. In the US alone, about 41.6% of the population is deficient in vitamin D. Deficiencies rise to 82.1% in the black population and 69.2% in the Hispanic population [1]. Vitamin D is essential for healthy bone growth, quality and maintenance. It is critical for calcium homeostasis by promoting calcium absorption in the intestines when levels are low [2]. Deficiencies in vitamin D can create chronic diseases in the body.

Chronic vitamin D deficiency has many consequences, including [3, 4]:

Cardiovascular disease
Colon, prostate, breast and ovarian cancer
Hypertension
Multiple sclerosis
Type 1 diabetes
Depression

Recommended levels of vitamin D:

The US Institute of Medicine recommends 600 IU/day for ages 1-70 and 800 IU/day for ages 71 and over when getting vitamin D through sun exposure, which will meet 97.5% of the population [5]. The most natural and effective source of vitamin D is from direct sunlight on the face, arms and legs when the sun is at its strongest from 10 am to 3 pm.

How much time in the sun do you need?

To get the recommended 600 IU/day of vitamin D, the average person will only need to spend about 10-15 minutes at least 3 times a week in the summer sun when the face, arms and legs are exposed [6]. However, this answer differs depending on skin type, weight and age [7].

Dark-skinned people will typically require more sun exposure than people with light-skin due to the increased melanin in dark skin. Dark-skinned people should aim for closer to 20 minutes a few times a week in the summer sun.
Body fat helps better absorb vitamin D, so those with more body fat have a larger vitamin D reservoir for times when sunlight is scarce to the body. Therefore, more body fat means less sun exposure is needed to meet the same requirements.
Not only do older people produce less vitamin D naturally, but they also have a harder time converting ultraviolet B (UVB) light into the vitamin D precursor. Older people should aim to get 20-30 minutes of sun a few times a week or talk to a doctor about supplementation.

Other sources of vitamin D?

Not everyone has the ability to get sunlight each day, especially those who live in colder climates for part of the year (like myself) or places with polluted air that block UVB light. There are some plant-based foods that are fortified with vitamin D (ie. nut milk and tofu), however, you would need to eat unrealistic amounts of these foods to get the recommended levels of vitamin D. I highly recommend talking to your doctor or dietitian about taking a vitamin D2 supplement of up to 1,000 IU/day to 5,000 IU/day (25-125 micrograms) if you feel you don’t get enough sunlight. Supplementation requires higher levels of vitamin D as it does not absorb as easily in the body.

Don’t forget sunscreen!

As important as it is to get vitamin D, it is just as important to protect your skin from harmful UV rays and prevent skin cancer. Studies have shown that there is no significant difference in vitamin D absorption in those who wear sunscreen and those who don’t [8].

Unfortunately, the most popular sunscreen brands are loaded with toxic chemicals, most commonly oxybenzone, retinal palmitate, parabens and fragrances with phthalates. These chemicals are known endocrine disruptors and can even cause skin tumors.

Here are some sunscreen brands that are free of toxic chemicals and can be found at your local stores like Target or Walmart:

For kids:

For beach/sport:

Plastic-Free Brands:

There are several other safe brands that I have not listed here. If you are ever questioning the safety of your sunscreen, you can input the brand right into the EWG website and they will give you the safety rating of your sunscreen.

A Guide to Vitamin D