Sunlight and Vitamin D

During the month of April, if you enjoy bicycle riding, you may enjoy taking part in an annual 30-day Bike Ride (sponsored as a fundraiser for World Bicycle Relief). 30 Days of Biking is a pledge to ride your bike every day in April and share your adventures online with the hashtag #30daysofbiking. You can ride your bicycle, regular or recumbent, or your three-wheel adult tricycle. On the website,, it says:

“There’s no minimum distance—down a hill and around your garage count just like a 20-mile commute or a 350-mile charity ride. If you miss a day, no worries. Just keep riding and don’t give up! It’s all for giggles, or as serious as you want it to be. What matters is that we’re all in this together. And yep, spin class counts!”

Whether you take part in the April 30-day Bike Ride or not, this is a good week to focus on Law of Health #4: Sunlight and a closely related topic—vitamin D.

Vitamin D

The “sunshine vitamin” appears to form under the skin when it is exposed to sunlight. Most of the nutrient is formed in reaction to sunlight, but small amounts are also found in foods such as oily fish and eggs. Scientists have discovered a link between vitamin D levels and our ability to deal with glucose. There are vitamin D receptors in almost all the cells in the body, suggesting vitamin D plays a role in most chemical processes but some of the more interesting roles in vitamin D include beta cell function and regulation–the cornerstone of diabetes.

Vitamin D is provided by skin synthesis by UVB-irradiation from summer sunshine and to a small extent by absorption from food. However, these processes become less efficient with age. Many experts suggest that ≥1000–2000 IU [25–50μg] of vitamin D daily is necessary for older people. Some studies suggest that correcting vitamin D deficiency could reduce insulin resistance and improve insulin secretion. Health Canada advises all adults over the age of 50 to take a vitamin D supplement of 400 IU each day.

You are at greater risk for vitamin D deficiency if you are over 50, obese, diabetic, or vegan. This is because most dietary sources of Vitamin D come from animal-based foods. You can ask your doctor to order a vitamin D blood test. According to my health care provider, the normal range is 20-79 ng/mL. Even though I take a vitamin D supplement, I’m looking forward to the sunny days of April when I can ride my adult tricycle!

References to vitamin D can be found at

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