Vitamin D is a fat-soluble vitamin and one of the most important vitamins for our overall health. Though five forms of it are known to science (vitamins D1, D2, D3, D4 and D5), the two forms that matter most to us are D2 (ergocalciferol, a synthetic form made by irradiating fungus and plant matter) and D3 (cholecalciferol, a natural form created in our bodies from sunlight exposure). Aside from being more natural, vitamin D3 is 87 percent more potent than vitamin D2, making it the best form of vitamin D for our bodies.
What does vitamin D do?
Facilitates calcium absorption — Vitamin D aids the absorption of calcium in our stomachs while maintaining the concentrations of serum calcium and phosphate needed to enable normal bone mineralization. This is why so many vitamin D supplements also contain calcium (and vice versa): The two nutrients work in tandem to boost bone health. Without sufficient vitamin D, our bones can become brittle, thin and misshapen. An extreme deficiency can lead to rickets (softening and weakening of the bones) in children and osteoporosis (abnormal loss of bone tissue) in older adults.
Maintains cardiovascular health — Without adequate amounts of vitamin D, the calcium in our bodies can build up in our arteries, leading to atherosclerosis (hardening of the arteries). People suffering from atherosclerosis have a much greater risk of developing heart disease — including heart attacks and strokes — than those with healthy arteries. Additionally, studies have shown that people with low vitamin D levels are more likely to suffer from high blood pressure, high cholesterol and type 2 diabetes.
Modulates cell growth — When operating as cholecalciferol, vitamin D is known to decrease cell division and increase the normal maturation of cells. It also helps block the production of proteins that prevent apoptosis (cell death) in cancer cells, while aiding the proteins that cause it. For these reasons, vitamin D — like several other vitamins, such as the antioxidant vitamin C — can directly slow the development of cancer.
Regulates mood — Have you ever noticed that your mood often improves after spending time in the sunshine? This is because the vitamin D that our bodies synthesize from sunlight increases our monoamine levels. Monoamines, of which serotonin is perhaps the best-known, are neurotransmitters that play a central role in regulating our moods. In fact, many commercial antidepressants work by increasing the amounts of monoamines in our brains. However, unlike commercial antidepressants, sunlight-derived vitamin D increases our monoamine levels naturally and without awful, life-destroying side effects.
How much vitamin D do we need?
The recommended daily intake (RDI) of vitamin D in adults is 600 international units (IU) in both men and women. However, like so many RDIs from official sources, this number is alarmingly low. Since our bodies produce 10,000-20,000 IU of vitamin D after a mere 30 minutes of full-body sunbathing, it’s not difficult to understand that receiving five-digit levels of vitamin D per day (from sunlight or supplements) is not only safe but desirable. 10,000 IU per day, for example, is a good amount for most healthy adults. Moreover, according to Jeff T. Bowles, author of the book The Miraculous Results of Extremely High Doses of Vitamin D3, consuming huge doses of cholecalciferol in supplement form (between 25,000 and 100,000 IU daily) can massively improve our health.
Few foods contain vitamin D, and it’s virtually impossible to obtain adequate levels of it from diet alone. That said, the following foods are good dietary sources of vitamin D: fatty fish (especially salmon, mackerel and tuna), fish oils like cod liver oil, raw milk, cheese and egg yolks.
Sources for this article include: