Vitamin D has been considered an essential nutrient for humans for quite some time. Only recently, however, has the full array of benefits of this fat soluble nutrient come to be fully appreciated. Recent research indicates that suboptimal vitamin D status is wide spread, particularly in the northern United States and this could be having a significant impact on our health.
Traditionally, nutritionists have recognized the importance of vitamin D in calcium absorption and bone metabolism. Rickets, a pathological deficiency of vitamin D, was one of the first manifestations of urbanization and a highly processed diet. Pregnant and nursing mothers, along with their children, were crowded into dark tenements without access to sunlight. Compounded by a highly processed diet this often led to Rickets, a childhood disorder which is characterized by a softening and weakening of the bones.
Although Rickets is fairly rare in developed countries today, we now know that a deficiency of vitamin D significantly increases the risk of most types of cancer, multiple sclerosis, Type 1 diabetes, Seasonal Affective disorder (SAD), hypertension, and heart disease. Additionally, we now know that vitamin D moderates excessive inflammation by down-regulating the pro-inflammatory molecule NF Kappa B. This in turn implicates a vitamin D deficiency in a host of other chronic inflammatory diseases including arthritis and Alzheimer’s.
So, how can we be sure that our clients are getting enough vitamin D? According to a recent review “The Clinical Importance of Vitamin D (Cholecalciferol): A Paradigm Shift with Implications For All Healthcare Providers”, by Drs. Vasquez, Manso and Cannell (copies available upon request), the safe and reasonable range to promote optimal health and reduce the risk of several serious diseases is 1,000 IU/day for infants, 2,000 IU/day for children, and 4,000 IU/day for adults. The National Institute of Health (NIH) Office of Dietary Supplements has put the upper limit (UL) for vitamin D at 1,000 IU for infants under 12 months and 2,000 IU for all others. Although, in light of recent research, their figures seem to be low, prudence would dictate that Nutritional Therapists recommend at or below these levels for vitamin D supplements unless periodic monitoring of serum vitamin D and calcium are performed.
One of the best ways to get adequate vitamin D is through appropriate exposure to sunlight. Unfortunately, particularly in Northern latitudes, this is often difficult. The ability to produce vitamin D from sun exposure varies with geographical location, skin pigmentation, percentage of body fat, and age.
Humans are exquisitely adapted to produce optimal vitamin D in their indigenous homelands under traditional lifestyles. Unfortunately, we, for the most part, do not live in our indigenous homelands and don’t live traditional lifestyles. This causes big problems with vitamin D status!
Skin pigmentation is adapted to sun exposure. People living in the higher latitudes have developed light skin to help them take advantage of every possibility to produce vitamin D from sunshine. In latitudes greater than 37 degrees (we’re above 40 degrees N here in the Northwest, San Francisco is at 38 degrees N) it is all but impossible to make vitamin D in the winter months. The further north one lives the shorter the vitamin D making season. Typically, vitamin D can be produced from 10am to 3pm during the spring, summer and fall. How many of our clients are regularly getting sun exposure between 10am and 3pm?
On the other hand, people from the lower latitudes with high exposure to sun light have darker pigment to protect them from the dangers of over exposure to Ultra Violet (UV) radiation, which can cause premature aging and several different types of skin cancer. Statistics from the U.S. Department of Agriculture indicate that African American women have a vitamin D status that is 40% lower than Caucasian women. This is particularly disturbing considering that most Caucasian women are deficient. It has been known for some time that African Americans have a lower cancer survival rate than Americans of European descent. We now understand that vitamin D status plays a significant role in these differing outcomes. Almost certainly this is a factor also in the higher rates of hypertension, heart disease, and perhaps diabetes among African Americans.
On the other hand, lightly pigmented races relocated to tropical and subtropical latitudes have suffered their own ravages. In Australia there is an epidemic of skin cancer. In the last twenty years the already high rates of cancer have doubled in spite of a huge campaign to use sunscreens. In retrospect, the use of sunscreen decreases the skins ability to produce vitamin D by 97% to 100% by blocking the UVB radiation which produces vitamin D. By preventing burning of the skin, sunscreens may prevent certain types of skin cancer such as actinic keratosis (AK) and squamous cell carcinoma (SCC), but because they are less protective of UVA than UVB radiation and promote longer exposure by preventing sunburn they may actually increase the risk of basal cell carcinoma (BCC) and the deadliest form of skin cancer, cutaneous malignant melanoma (CMM).
In general, contemporary attitudes towards sun exposure and sunscreens have not served us well. We should get some exposure to the sun every day that it is possible, we should not use sunscreen, but we should never expose our skin to the point of burning. The pain and inflammation of sun burn is our bodies’ way of saying “get out of the sun” and we should respect that. Having said that, it is important to be intelligent about sunscreen. If we are going to be overexposed for our pigment type, in actuality, it is certainly better to use sunscreen than to burn. If we go to Hawaii in the winter months, most of us will not be inclined to sit in the shade except for 5 or 10 minutes per day, so sunscreen should be used to avoid excessive exposure.
According to a recent review on vitamin D, published in the “Alternative Medicine Review”, a respected peer reviewed journal, the economic burden of vitamin D deficiency in the United States in between 40 and 53 billion dollars per year! The economic burden due to excess UVA radiation is only 5 to 7 billion dollars per year. Obviously, these figures could be vastly improved if people would get adequate sun exposure but avoid sun burn and overexposure.
Dietary intake is the only other source of vitamin D intake. If it’s not produced in the skin as a result of appropriate exposure to UVB radiation then it must be ingested either from food or supplements. Although, obviously we would prefer to get our vitamin D from whole foods, this to can be problematic.
The primary dietary source of vitamin D is oily fish or cod liver oil. A 3 ½ ounce piece of salmon contains approximately 360 IU of vitamin D followed closely by mackerel with 340, Sardines with 250 and Tuna with 200. The problem with eating fish as a primary source of vitamin D is that fish often contain mercury and consuming enough fish to supply the optimal amounts could pose a very real risk. Farm raised fish should be avoided. An egg, according to the U.S.D.A., contains about 20 IU’s of vitamin D. It can be assumed that a free-range and grass fed egg would have significantly more. Liver contains 15 IU’s of vitamin D, but again, it would be very important to obtain liver from an organic and grass fed source in order to get the maximum benefit and avoid toxicity.
Industrialized milk, commercial baby formulas, and many processed cereals are fortified with vitamin D2. In the typical highly processed American diet this has been very important in the prevention of Rickets. Whole grains and milk even from organic or grass fed sources does not contain vitamin D in any significant amounts. Since Nutritional Therapists and their clients who are interested in natural health often avoid fortified, processed foods, it is important to recognize that they must get their vitamin D from other sources.
Because of the logistics of getting enough sun exposure and the general lack of vitamin D in most diets, supplementation should be considered for most individuals, particularly in the Northern latitudes. The form of vitamin D produced in the skin and found in whole foods is vitamin D3 (cholecalciferal). Fortified foods and some supplements contain vitamin D2 (ergocalciferol). Vitamin D2 is manufactured by irradiating fungi and although useful, is less efficiently converted into the biologically active form of vitamin D (calcitriol). Cod liver oil is a rich source of vitamin D3, containing 1,360 IU’s per tablespoon. For many individuals this could be a useful supplemental source if they do not object to the taste and have the ability to properly digest fats. It is important to use only sources that have been tested for contamination, particularly mercury. Most of the professional grade supplement manufactures have a vitamin D3 supplement. To ensure efficient uptake, emulsified products should be considered.
Realistically, as Nutritional Therapists, we must conclude that very few of our clients are receiving enough vitamin D from either appropriate exposure to sunshine or diet. In view of the importance of vitamin D for optimal health and the prevention of most of today’s chronic and degenerative diseases, we need to evaluate vitamin D status, make appropriate dietary and lifestyle recommendations, and recommend high quality supplements when appropriate.
Gray L. Graham BA, NTP