Vitamin D is increasingly being recognized as a powerful super-nutrient essential for good health. This nutrient is already well known to improve bone health and protect against osteoporosis, but increasing research is revealing that vitamin D has a much wider role to play in our health.
Receptors for vitamin are found in most of the cells in the body and research has made a number of exciting discoveries about this super-nutrient. Insufficient vitamin D levels are linked to virtually every age-related disorder including cancer, heart disease, diabetes, chronic inflammation, as well as depression and autoimmune diseases. High levels of vitamin D are also known to strengthen the immune system, leading to substantially fewer colds, flu, and other viral infections.
What is vitamin D?
Vitamin D is not actually a real 'vitamin' as we are all capable of manufacturing it from scratch. In the skin, a chemical made from cholesterol called 7-dehydrocholesterol is converted into vitamin D3 when it comes into contact with a certain ultraviolet (UV) light. Despite our ability to manufacture it, the process requires adequate sunlight and in its absence, deficiencies can easily occur.
Vitamin D from sunlight
Sunlight is composed of electromagnetic radiation of varying wavelengths, ranging from the long-wavelength infrared light to the short-wavelength ultraviolet. Ultraviolet light is further subdivided into UVA, and the even shorter-wavelength UVB radiation. Although UVB causes sunburns, it is also the component that initiates Vitamin-D production in the skin.
UVA, known as the "tanning ray," is primarily responsible for darkening the pigment in our skin. UVA is less energetic than UVB, so exposure to UVA will not result in a burn, unless the skin is photosensitive or excessive doses are used. UVA penetrates more deeply into the skin than UVB, due to its longer wavelength. It is now considered to be a major contributor to the high incidence of non-melanoma skin cancers. Seventy-eight percent of UVA penetrates glass so windows do not offer protection.
UVB is the ultraviolet wavelength that stimulates our bodies to produce vitamin D. It is sometimes called the "burning ray" because it is the primary cause of sunburn (erythema). However, UVB also initiates beneficial responses, stimulating the production of vitamin D that the body uses in many important processes. It also causes special skin cells called melanocytes to produce melanin, which is protective. UVB also stimulates the production of Melanocyte Stimulating Hormone (MSH), an important hormone in weight loss and energy production.
Although the task of "getting enough sunlight" may seem straightforward enough, it's not that simple. UVB light - the kind needed for skin synthesis of vitamin D - is not always present with the same intensity just because there is visible sunlight. The intensity of UVB light varies dramatically with geographical location (latitude), the time of year, time of day, degree of cloud cover, and other factors. In higher-latitude countries (such as the UK), UVB light in the range required to produce vitamin D, may not be available except for a few hours in the middle of the day.
Skin pigmentation also plays an important role in skin synthesis of vitamin D. Darker skin pigmentation means less vitamin D synthesis per minute exposure to UVB light. So those with darker skin will need to spend longer in the sun to obtain the same amount of vitamin D.
It takes about 24 hours for UVB-stimulated vitamin D to show up as levels of vitamin D in the blood. Cholesterol-containing body oils are critical to this absorption process. Because the body needs 30-60 minutes to absorb these vitamin-D-containing oils, it is best to delay showering or bathing for at least one hour after exposure.
Vitamin D from Food
For the reasons stated above, it can be difficult for most people to obtain sufficient levels of vitamin D from sunlight alone. The rest must be made up from food.
The few dietary sources of vitamin D are foods like oily fish (salmon, mackerel, tuna, sardines), egg yolks, and organ meats like liver.
The assimilation and utilization of vitamin D is also influenced by the kinds of fats we consume. High levels of both polyunsaturated and monounsaturated fatty acids in the diet decrease the binding of vitamin D to D-binding proteins, which are key to the beneficial actions of vitamin D. saturated fats, on the other hand, like the kind found in butter and coconut oil, do not have this effect.
Another option is to take a vitamin D supplement. Make sure to supplement with vitamin D3 (cholecalciferol), which is the natural form of this vitamin, and not vitamin D2, which is the synthetic form.
Optimizing your vitamin D levels is one of the simplest, yet most beneficial things you can do to protect your health.