Summer: synonymous with pool parties, summer flings, smoothie bowls, Netflix binges (come on I can’t be the only one?) and of course that sweet summer glow otherwise known as a tan. If you want to be a nerd about it, you might also say that summer is synonymous with vitamin D. #freakfact
(In this blog post we discuss what vitamin D does for our health and why it's so important. Check out our other Vitamin D posts on vitamin D deficiency, three surprising vitamin D benefits, and the different sources of vitamin D to learn more!)
The Discovery of Vitamin D
Vitamin D’s existence was first considered in 1840 when a Polish physician discovered that the incidence of rickets, a skeletal disorder occurring in children living in the industrial center of Warsaw, was far greater than children living in the countryside. He concluded that the relative difference in the prevalence of rickets was due to sun exposure. His hypothesis was not well received and largely ignored by mainstream medicine.
In 1980, Sir Edward Mellanby discovered that beagles housed exclusively indoors and fed a diet of oatmeal developed rickets which, with the addition of cod liver oil, could be treated successfully. Further tests and experimentation followed, and vitamin D was discovered.
The different forms of Vitamin D
There are different forms of vitamin D. The most important for humans are vitamin D2 and vitamin D3.
D2 is synthesized by plants. D3 is synthesized by the skin when it is exposed to ultraviolet B (UVB) rays (in real person speak: the sun gods).
Vitamin D is not actually a vitamin, but rather a prohormone. When our body is exposed to, or receives, vitamin D, it activates the vitamins in the liver and kidneys. This activation process (known as vitamin synthesis) turns the vitamin D into a hormone (or activated vitamin D).
We can access vitamin D via sun exposure, a limited number of foods, and supplements.
Health Benefits of adequate Vitamin D levels in the Body
So why do we need Vitamin D? Vitamin D is linked to numerous health benefits due to its ability to influence genetic expression. The following is a list of vitamin D’s proposed health benefits:
Promotes healthy bones – Vitamin D stimulates the absorption of calcium and phosphorus into the body, both of which are essential for maintaining bone health. A vitamin D deficiency in a child may manifest as rickets, and in an adult as osteomalacia (softening of the bones) or osteoporosis.
Prevents Cancer – Early stage epidemiologic research suggests that the incidence of, and death rates for, certain cancers are lower among individuals living in southern latitudes, where levels of sunlight exposure are higher. Researchers think that the variation in vitamin D levels might explain the discrepancy.
Vitamin D regulates cell growth and cell-to-cell communication. Some studies have suggested that the hormonally active form of vitamin D may slow or even reduce cancer progression by promoting cellular differentiation, decreasing cancer cell growth, stimulating cell death, and preventing angiogenesis or new blood vessel formation.
Strengthens immunity - Vitamin D regulates the expression of genes that influence the immune system. This means that Vitamin D assists the body to attack and destroy bacteria, viruses, and infections, including the common cold and flu. In one study, children given 1,200 international units of vitamin D per day for 4 months during the winter had a reduced risk of contracting the influenza A infection by over 40 percent.
Reduces risk of diabetes - Vitamin D may help to reduce the risk of insulin resistance by improving the body’s sensitivity to insulin (the hormone responsible for regulating blood sugar levels). Insulin resistance is usually a precursor to type 2 diabetes.
Vitamin D has been linked to glucose metabolism. One study found that participants with low vitamin D levels were more likely to develop type 2 diabetes, pre-diabetes, or metabolic syndrome, regardless of their weight. In obese and lean participants alike, it was found that those with a metabolic disorder had lower levels of vitamin D, and those without metabolic disorders had higher levels of vitamin D. These findings indicated that “vitamin D is associated more closely with glucose metabolism than obesity”,
Vitamin D has also been linked to a decrease in the risk of cardiovascular disease, suppressing autoimmune responses associated with multiple sclerosis, rheumatoid arthritis, and Crohn’s disease, and preventing and treating hypertension.