Vitamin D is also called sunshine vitamin because it is synthesized from cholesterol, when our body is exposed to the sun. Though it is called a vitamin, it is not strictly a dietary vitamin as the body gathers it in adequate amounts when sunlight touches the skin. It is only we, humans, who can synthesize it from sun exposure; dogs and cats cannot, and hence have to get it from their diet.
Why do we need Vitamin D
The main functions of vitamin D are development and maintenance of mineral on homeostasis, and skeleton integrity. It is also necessary for brain development, cell growth, blood pressure regulation, mammary gland development. Calcium and phosphorous perform different functions in our body. They are essential for the maintenance of healthy bones. Vitamin D, besides aiding the absorption of calcium and phosphorous, helps to maintain their metabolism. Vitamin D supplementation in pregnant women helps babies to curb bacterial vaginosis, gestational diabetes mellitus, and reduces the risk of C-section in the mother. The other benefits of vitamin D supplementation include higher birth weight, increased head circumference, and reduction in developmental language abnormalities. It also helps prevent osteoporosis, osteomalacia, and fractures. While these are proven benefits, noncalcemic benefits include prevention of cancer of the colon, cardio-vascular diseases, type 1 and type 2 diabetes, wheezing, and multiple sclerosis.
Vitamin D requirements
- We do not attribute importance to anything that is available free. Same is the case with Vitamin D. It is probably the most under rated nutrient in the world. There are no clear recommendations as regards the amount of sun exposure one requires to meet our requirements. This is partly due to the uncertainty about skin cancer risk from sunlight. It is almost impossible to meet our body’s vitamin D requirements from our diet. Sunlight is the only reliable way to generate it.
- Our body requires 1000 IU of vitamin D daily. 30 minutes of uninterrupted exposure to sunlight between 10 am to 3 pm is assumed to be enough to produce 1000 IU of vitamin D. A test that is commonly done to check vitamin D levels is 25 hydroxyvitamin D3 – 25(OH) D3, and a person is considered to be deficient if the levels are below 20, and insufficient if levels are between 21 and 29.
- The healing rays of natural sunlight cannot penetrate glass. So you don’t generate the vitamin when sitting in your car or home. Similarly, Skin creams and lotions reduce the ability of the skin to absorb sun’s rays.
- The sun shines the brightest at the equator. If you are living away from the equator, you would require a longer exposure to the sun. Hence, people living in USA, Canada and UK require longer exposure.
- The ultraviolet rays of the sun takes longer to pierce dark skin. Hence, to generate the same quantity of vitamin D, people with dark skin may require 20 to 30 times as much exposure to sunlight as fair skinned people.
Vitamin D from Diet
If our body is not able to produce sufficient vitamin D because of insufficient exposure to sunlight, then it needs to get it from food and food supplements. Experts believe that people with vitamin D deficiency should consume 1000 IU of vitamin D each day. Elderly people, as well as people with dark skin should consume extra.
There are not many foods that contain vitamin D. Fish like salmon, tuna and mackerel, and fish liver oils are the best sources of vitamin D. It is present in small quantity in beef liver, cheese and egg yolks. It is also sourced from fortified foods. Most US milk is fortified with vitamin D at 100 IU/cup.
Risks from vitamin D deficiency
Globally an increasing number of people aren’t getting sufficient sun exposure in order to produce substantial levels of vitamin D, increasing their risk of falling sick. Besides poor bone health, vitamin D deficiency can also be linked to multiple sclerosis, breast cancer, diabetes, heart disease and depression.
Scientists have found that Vitamin D deficiency increases risk of type 1 diabetes. According to a study at Harvard School of Public Health (HSPH), having adequate levels of vitamin D during young adulthood may reduce the risk of adult-onset type 1 diabetes by 50%.
Lead author Kassandra Munger from Harvard School of Public Health (HSPH) said, “individuals who avoid direct sun exposure, who wear much clothing to protect themselves from the sun, have a diet low in fatty fish, or have darkly-pigmented skin are more likely to have low vitamin D levels.”
Pregnant women who take an adequate amount of vitamin D during gestation, may experience positive immune effects. Not taking the recommended could negatively impact the health of the mother and her fetus. 4000 IU of vitamin D3 is considered adequate for supplementing pregnant women.
Vitamin D levels in winter
At the 2012 American Society of Clinical Pathology Annual Meeting, researchers from Vanderbilt University Medical Center in Nashville, Tenn, reported that women with arthritis, diabetes and some other chronic conditions are much more susceptible to a drop in vitamin D levels during the winter months. Hence, they require additional supplementation during winter.
Current lifestyles prevent most of us from being exposed to sunlight and, hence the incidence of deficiencies is on the rise. Vitamin D certainly has a myriad of benefits for everyone. Health experts recommend exposing the arms for just about five to 10 minutes of sunlight during mid morning or mid-afternoon. On the other hand, individuals with darker skin are recommended 15 to 60 minutes daily. The experts also advise more sun exposure during winters, anywhere between 10 to 30 minutes daily. Make sure you get your daily dose of sunlight, and go on to lead a happier and healthier life.