Vitamin D - the sunshine vitamin

 

Missing out on the "sunshine vitamin” (Vitamin D) has consequences for more than just bone health. In a retrospective study of patients tested for COVID-19, researchers at the University of Chicago Medicine found an association between vitamin D deficiency and the likelihood of becoming infected with the coronavirus.

“Vitamin D is important to the function of the immune system and vitamin D supplements have previously been shown to lower the risk of viral respiratory tract infections,” said David Meltzer, MD, PhD, Chief of Hospital Medicine at U Chicago Medicine and lead author of the study. “Our statistical analysis suggests this may be true for the COVID-19 infection.”

Half of Americans are deficient in Vitamin D, with much higher rates seen in African Americans, Hispanics and individuals living in areas like Chicago where it is difficult to get enough sun exposure in winter.“Understanding whether treating Vitamin D deficiency changes COVID-19 risk could be of great importance locally, nationally and globally,” Meltzer said. “Vitamin D is inexpensive, generally very safe to take, and can be widely scaled.”

September brings the end of summer in the northern hemisphere and, for many of us, that means less time in the sun. The sun's rays provide ultraviolet B (UVB) energy, and the skin uses it to start making vitamin D.

Vitamin D is known for its importance in bone health and would be essential if it did nothing else. But researchers have discovered that it's active in many tissues and cells besides bone and controls an enormous number of genes, including some associated with cancers, autoimmune disease, and infection. Hardly a month goes by without news about the risks of vitamin D deficiency or about a potential role for the vitamin in warding off diseases, including breast cancer, multiple sclerosis, and even schizophrenia. In June 2008, a study published in the Archives of Internal Medicine found that low blood levels of vitamin D were associated with a doubled risk of death overall and from cardiovascular causes in women and men (average age 62) referred to a cardiac center for coronary angiography.

 At a scientific meeting in May 2008, Canadian researchers reported that vitamin D deficiency was linked to poorer outcomes in women with breast cancer.

One of the few randomized trials testing the effect of vitamin D supplements on cancer outcomes, postmenopausal women who took 1,100 international units (IU) of vitamin D plus 1,400 to 1,500 milligrams of calcium per day reduced their risk of developing non-skin cancers by 77% after four years, compared with a placebo and the same dose of calcium. The evidence is so compelling that some experts already recommend at least 800 to 1,000 IU of vitamin D per day for adults.

Latitude and vitamin D production in the skin Except during the summer months, the skin makes little if any vitamin D from the sun at latitudes above 37 degrees north (in the United States, the shaded region in the map) or below 37 degrees south of the equator. People who live in these areas are at relatively greater risk for vitamin D deficiency.

In search of vitamin D

Under the right circumstances, 10 to 15 minutes of sun on the arms and legs a few times a week can generate nearly all the vitamin D we need. Unfortunately, the "right circumstances" are elusive: the season, the altitude, the time of day, where you live, cloud cover, how much clothing you are wearing, and even pollution affect the amount of UVB that reaches your skin. What's more, your skin's production of vitamin D is influenced by age (people ages 65 and over generate only one-fourth as much as people in their 20s do), skin color (African Americans have, on average, about half as much vitamin D in their blood as white Americans), sunscreen use (though experts don't all agree on the extent to which sunscreen interferes with sun-related vitamin D production) and genetic abnormalities (my 23 and me test shows an inability of my body to convert sunshine into Vitamin D).

Lack of sun exposure would be less of a problem if diet provided adequate vitamin D. But there aren't many vitamin D–rich foods (see chart, below), and you need to eat a lot of them to get 800 to 1,000 IU per day. People who have trouble absorbing dietary fat — such as those with Crohn's disease or celiac disease — can't get enough vitamin D from diet no matter how much they eat (vitamin D requires some dietary fat in the gut for absorption). And people with liver and kidney disease are often deficient in vitamin D, because these organs are required to make the active form of the vitamin, whether it comes from the sun or from food.

Selected food sources of vitamin D
Food	Vitamin D (IU*)
Salmon, 3.5 ounces	360
Mackerel, 3.5 ounces	345
Tuna, canned, 3.5 ounces	200
Orange juice, fortified, 8 ounces	100
Milk, fortified, 8 ounces	98
Breakfast cereals, fortified, 1 serving	40–100

For these and other reasons, a surprising number of Americans — more than 50% of women and men ages 65 and older in North America — are vitamin D–deficient, according to a consensus workshop held in 2006. Growing awareness of vitamin D's benefits coupled with the risk of vitamin D deficiency has led some experts to recommend a blood test that assesses the amount of vitamin D in the body. The test measures the concentration of 25-hydroxy vitamin D3 in the body to vitamin D. You might want to ask your doctor about the test.

Deficiency is generally defined as a blood level less than 20 nanograms per milliliter, or 20 ng/mL (see chart). Levels that low have been linked to poor bone density, falls, fractures, cancer, immune dysfunction, cardiovascular disease, and hypertension. Many experts recommend a level of at least 32 and suggest that 800 to 1,000 IU of vitamin D per day is required to maintain that level.

Unless you live in the South and spend a fair amount of time outdoors, or you like eating lots of fatty fish and vitamin D–fortified foods, supplements are the easiest way to make sure you're getting 800 to 1,000 IU per day. (Higher doses may be prescribed if you've been diagnosed with vitamin D deficiency.)

Here is my favorite Vitamin D supplement (recommended by my MD/Naturopath) 

Also here is a free APP you can play around with as you work on getting sufficient Vitamin D to bless your health.

I’m not going to tell you exactly what to do for our weekly bonus challenge other than to say “Safeguard your health by making a daily effort to get enough Vitamin D.” Some ideas you might choose to try:

1. Purchase a Vitamin D supplement and take daily
2. Make sure to spend some time out doors in the sunshine each day wearing a bathing suit or shorts and a t-shirt
3. Keep a daily tally of Vitamin D supplied by the foods you eat (unfortunately Myfitnesspal cannot be set to track Vitamin D for you)
4. Add in one Vitamin D rich food to your daily diet each day this week
5. Have your health care provider order a Vitamin D test.

So you choose your strategy for getting more Vitamin D. Share it with your partner and work on it daily this week for 5 daily bonus points