Amazing Vitamin D

What It Does for Your Body and Mind

by Jan Cullinane

importance of our bodies getting sunlight in order to make vitamin D, or getting vitamin D through certain foods.

“The Sunshine Vitamin.” We’ve heard this nickname for vitamin D, and most of us know that our body makes its own vitamin D when certain wavelengths of sunlight (UVB) interact with a particular kind of cholesterol in our skin. However, what many of us may not realize are the many vital functions that this vitamin performs. According to the National Institutes of Health (NIH), it’s believed that more than 1,000 different genes are regulated by vitamin D, including 200 genes affecting just our cardiovascular system.

Vitamin D is one of only a few vitamins that our bodies manufacture. The scourge of rickets in the 17th century, although there is evidence of this disease long before that, resulted in muscle weakness, skeletal malformations, seizures, and slowed growth. The recognition that sunshine and/or cod-liver oil, both high in vitamin D, could prevent rickets was a huge discovery that led to understanding the

It’s believed about 40% of American adults have inadequate levels of vitamin D, and the higher levels of melanin in dark-skinned people decrease the amount of vitamin D they can produce. Other groups that often have lower-than-optimal vitamin D levels include adults over 55 (they tend to spend less time outdoors and skin becomes less proficient at converting sunlight to vitamin D as we age), those with inflammatory bowel diseases such as Crohn’s or Ulcerative Colitis (these diseases can lower the ability to absorb vitamin D from the gut), vegans/vegetarians (most food containing vitamin D is animal-based), and those taking certain medications such as prednisone or cholesterol-lowering drugs that interfere with the production of vitamin D.

Where you live affects the amount of vitamin D your body makes. Because of low or absent UVB sunlight from late October to late April, our skin makes little if any vitamin D at latitudes above 37 degrees north (above the line on the map below), during that portion of the year.

What Does Vitamin D Do?

• Boosts mood and lowers the chances of depression by helping convert the amino acid tryptophan into mood-regulating serotonin.

• Reduces tooth decay by absorbing and retaining phosphorous and calcium, necessary for healthy teeth and gums.

• Although the NIH recognizes that more research is necessary, “studies have consistently found that vitamin D levels are significantly lower in individuals with Alzheimer's disease and cognitive impairment compared to healthy adults.”

• Reduces eye inflammation and may help prevent macular degeneration.

• Higher vitamin D levels are linked with reduced chances of cancer in general and reduced insulin resistance.

• Vitamin D is vital for strong bones because it increases the absorption of calcium from the intestines. Those with adequate vitamin D levels have fewer cases of osteoarthritis, osteoporosis, and rheumatoid arthritis, as well as less knee pain and pain when walking. Adequate levels of vitamin D also lower the chances of stress fractures in the feet.

• Greater gut biome diversity (correlated with better health) is linked to adequate levels of vitamin D.

• Vitamin D helps regulate blood pressure and helps reduce “bad” cholesterol.

• Pregnant women with normal vitamin D levels are more likely to have healthy babies, and men produce sperm with better motility than men with lower vitamin D levels.

• Regarding COVID-19 and vitamin D, the journal PLOS ONE reviewed 1,176 patients admitted to an Israeli hospital between April 7, 2020, and February 4, 2021, and found that “a lower vitamin D status was more common in patients with severe or critical disease than in individuals with mild or moderate disease.”

Making/Getting Sufficient Vitamin D

For those who live below the 37th parallel, 10 to 30 minutes of mid-day sun a few times a week on our arms, legs, and/or abdomen may be sufficient, although pollution, the season, and age all affect vitamin D synthesis. As noted above, living above the 37th parallel, very little vitamin D is made by our body’s exposure to the sun, except during the summer months. And, although the use of sunscreen has been shown to reduce the risk of melanoma and squamous skin cancers, it does affect how much UVB light can interact with the cholesterol in our skin to make vitamin D. Sunscreen with an SPF (sun protection factor) of 15 filters out about 93% of the UVB light, an SPF of 30 blocks 97%, and an SPF of 50 filters out about 98%. And, don’t think you can make vitamin D sitting in front of a window or while driving your car. The glass blocks UVB rays.

There are food sources containing vitamin D, including oily fish (especially salmon, trout, mackerel, and sardines), cod liver oil, eggs, tuna, beef liver, cereals, and vitamin D fortified orange juice and milk. Symptoms of low vitamin D can include fatigue, mood changes, joint/bone/muscle pain, anxiety and/or low energy level.

There is a blood test to determine vitamin D levels, but there is no routine testing of it because the U.S. Preventive Services Task Force has not recognized an optimal vitamin D level. Those who are tested for vitamin D include those with GI conditions such as celiac disease or other inflammatory bowel diseases that affect the absorption of vitamin D from food, those who have osteopenia (lower than normal bone density) or osteoporosis, bones that break easily, those who take medications such as prednisone or certain anti-convulsants, or suffer from muscle weakness or dental abnormalities. Additional risk factors for low vitamin D include obesity and being over 65.

Numerous studies confirm that where you live affects your health and happiness. When it comes to vitamin D, where you live and what you eat can influence both health and happiness.