Vitamin D has been receiving more attention over the past several years. For several decades vitamin D was touted for its role in bone health, but recently evidence is mounting that its benefits are far more reaching. As research has become more abundant in the study of this vitamin we are beginning to see that it may play a vital function in metabolism and diseases. Vitamin D is obtained by exposure to sunlight and vitamin D rich foods in the diet. This article discusses how we can get an adequate amount of Vitamin D and the role it is believed to play in our overall health and disease prevention.
Where do we Get Vitamin D?
Vitamin D is most commonly obtained through diet and/or exposure to sunlight. Sunlight is actually the most natural and common way for vitamin D production in the body. It does not take a significant amount of time in the sun for sufficient exposure. About 10-20 minutes of sun exposure between 10am and 3pm (without sunscreen) to the arms and legs 3 times a week is usually sufficient to obtain an adequate daily supply of D. One problem with this method is the fact that people living in globally far northern or southern climates rarely get enough sunlight exposure in the fall and winter months not to mention that our efforts to protect ourselves from skin cancer blocks the specific rays (UVB) which are responsible for vitamin D synthesis in the body. Even those living in traditionally warmer climates may not get adequate sun exposure on a daily basis due to work schedules, cloud cover, pollution, age and the use of sun protective clothing and lotions. Due to our better awareness of excess sun exposure contributing to skin cancer we have begun to protect ourselves to the point that we are unintentionally limiting our natural ability for vitamin D production. If you are not able to average the 10-20 minutes of sun exposure a few times each week then diet is the next logical place to get your vitamin D.
Vitamin D3 (cholecalciferol) is the supplement form that is most recommended because of its bioavailability (able to be absorbed and used by the body). One of the foods that is highest in Vitamin D3 is salmon. Wild Alaskan salmon is the preferred choice. Farm raised salmon carries a number of other health concerns. Tuna is also high in D3. Other foods include fortified milk, fortified cereal and free range eggs. However, these foods together only supply a portion of daily vitamin D3.
What are Some Health Benefits of Vitamin D?
- Plays a significant role in helping the intestines absorb a number of other nutrients such as calcium and phosphorus. This is important for strong bones and a strong immune system.
- Provides calcium balance in the body which helps prevent osteoporosis and/or arthritis.
- Prevents osteomalacia (weakness of the muscular system and brittle bones in adults) and rickets (skeletal deformity seen in children).
- Helps to regulate blood pressure, reduces stress and tension, relieves body aches and pains due to spasm, reduces respiratory infections, aids insulin secretion, fights depression, aids skin health, and provides a protective lining for blood vessels.
- Research has also shown the possible importance for reduction in pre-eclampsia, prevention and recovery potential from cancer, diabetes mellitus prevention and hyperparathyroidism.
- Vitamin D seems to have positive effects on the immune system and there is some thought that it may play a role in preventing influenza. A lack of vitamin D from sunlight is one explanation for the increased influenza rates in winter.
Risk Factors of Vitamin D Deficiency
Some studies have shown that those with the lowest levels of vitamin D have more than double the risk of dying from heart disease, heart attacks and other causes when compared to those with the highest vitamin D levels. Low levels of vitamin D have also been associated with multiple sclerosis (MS). Some reasons that deficiency of D is thought to be a risk factor for MS include:
- The frequency of MS increases in northern and southern latitudes in relation to the equator which is correlated with the duration and the intensity of sunlight and vitamin D concentrations.
- MS is shown to be lower than expected in these northern latitudes in population groups that have a high consumption of vitamin D rich fatty fish.
- MS risk decreases with people who migrate closer to the equator from these far northern or southern latitudes.
How Much Vitamin D do I Need?
Despite our ability to get vitamin D from food and the sun, it is estimated that up to 75% of people are deficient. A daily multi-vitamin tablet does not provide sufficient vitamin D.
The government’s dietary recommendations (RDA) are 600 IU/day for 1-70 years of age, 800 IU/day for 70+ years, and 600 IU/day for pregnant and lactating women. These levels have been revised upward in recent years, but many experts believe that these recommendations are still far too low to maintain healthful vitamin D levels. They advocate for supplementation in the winter of about 4,000 or more IU per day and a dose of daily sunshine in the summer. Pregnant and nursing women should consult their doctor prior to supplementation.Vitamin D toxicity is rare though it can lead to hypercalcemia (too much calcium in the blood). An upper threshold has not been formally established. In healthy adults sustained intake of more than 50,000 IU per day can produce toxicity after several months. Vitamin D production from sunlight exposure does not result in toxicity as it can from supplemental form.
Ultimately, experts advise that having your vitamin D level tested through your blood serum is a more accurate guide in determining necessary supplementation.