Something New Under the Sun:
Adapting to Change in the 21st Century


AnthroHealth News

March 2007

Volume 6, Issue 3


Vitamin D is the Key


The missing key to health and well-being for most of us living in the United States is an adequate level of vitamin D. Vitamin D is the Key that will unlock better health. Vitamin D is not actually a vitamin. Instead, it comes in a variety of forms from prehormone to prohormone and finally to the active hormonal form. Since it is not a vitamin, it is extremely difficult to get it from food, whereas it is relatively easy, depending on your skin color and where you live, to get vitamin D by exposing unprotected skin to UVB radiation. This essay will provide you with tools to estimate how much vitamin D you are currently getting, either through your diet or through sun exposure.



The first step is to determine your current level of exposure to UVB radiation. To do so, fill in the attached worksheet labeled: UVB Radiation Exposure and Vitamin D Supplementation. This information will provide you with some idea of your UVB radiation exposure during your childhood and as an adult. For instance, if you were born in February in Seattle, WA, the odds are good that you were born with a suboptimal level of vitamin D in your blood. Your vitamin D profile may have improved during your childhood if you have light skin and spent at least 20-40 minutes between 10 am and 3 pm outside each day during the summer months without using sunscreen. However, if you have dark skin, you may have needed to spend the entire five hour period outdoors to achieve the same blood level of vitamin D that a child with a light skin color could achieve in 40 minutes.

If you were born in Phoenix, AZ during July, you were probably born with an adequate level of vitamin D if your mother had light-to-moderate skin color. If you also have light-to-moderate skin color and you spent enough time outdoors as you grew older, you have probably been able to maintain good levels of vitamin D in your blood. The highest levels of UVB radiation in the United States occur in the Southwest region and in southern Florida. Individuals living in these locations have the opportunity to achieve UVB radiation exposure for more months during the year than is true for those living at higher latitudes, such as Seattle, so it is easier for them to maintain adequate blood levels of vitamin D. However, this is not necessarily a given. If your mother was Muslim, wore traditional clothing, and kept you indoors when you were a baby and young child, then the odds are extremely high that you were born with inadequate levels of vitamin D, and this would not improve during childhood. This is true even if your mother lived in a region of high, year-round UVB radiation. Rickets in infants and young children, and osteomalacia in adult women, are extremely common among traditional Muslim women. Muslim women in Saudi Arabia who receive essentially no UVB radiation exposure despite their location, have almost undetectable levels of vitamin D and give birth to infants similarly deprived. This problem begins for females at adolescence as their clothing and behavior come under more cultural restrictions. Rickets reappears and is quite common among Saudi adolescent females. Therefore, in addition to determining when and where you were born and grew up, you must take into account any cultural practices that might affect your UVB radiation exposure.

Receiving UVB radiation exposure solely on weekends can be dangerous. You are more likely to overexpose yourself and receive a burn. This severe, intermittent exposure may be associated with the development of melanoma. It is important to be very careful about your exposure on weekends. The best way to obtain adequate levels of vitamin D from UVB radiation exposure is on a daily basis for the length of time appropriate for your skin color. However, since most adults work during the hours of 10 am to 3 pm, very few are able to obtain adequate UVB radiation exposure during the week. For those who have light skin color, taking a 20-minute walk outside during your lunch break, and two 5-minute walks during the morning and afternoon breaks may be adequate. Again, this level of exposure will be much too little if you have dark skin color.

If you suffered any severe, blistering burns as a child and/or adult, you should have your skin checked out by a dermatologist to determine whether you have any cancerous or precancerous growths. If you do have such growths, you will need to avoid UVB radiation exposure and obtain your needed vitamin D via diet and supplementation. The best supplementation is cholecalciferol (vitamin D3), unbound to vitamin A or calcium, in 1000 IU pills. If you do not have cancerous/precancerous growths, you can probably obtain your vitamin D from UVB radiation exposure. However, you must be very careful not to overexpose yourself. If you have light skin color, with light eyes, and blond or red hair, you should ensure that your UVB radiation exposure does not exceed 30 minutes per day, and that exposure should probably occur in 10 15 minute segments. After that, make sure to wear protective clothing and sunscreen. The deeper your skin color, and the darker your hair and eye color, the longer you can be exposed to UVB radiation without burning. And the longer you will need to be exposed to obtain adequate levels of vitamin D. Saudi children with moderate skin color, living in a region of UVB radiation exposure equivalent to that of the Southwest United States and the Caribbean, need in excess of 60 minutes per day of UVB radiation exposure to obtain levels of vitamin D high enough to prevent rickets. A study in Libya found children there needed in excess of three hours per day of exposure to raise their vitamin D levels to the levels achieved by very light-skinned children living in Norway during their much briefer summer exposure.

Although students are generally not in school during the summer months, this is changing as many school districts increase the length of the school year. In addition, some school districts are considering eliminating recess and outdoor playtime during the lunch period for those in elementary school. The reasons given for this are that recess interrupts learning sessions, and that in-class activities can be both fun and educational. Eliminating recess ignores the needs of children to have periodic breaks, to work off excess energy, and to receive UVB radiation exposure during the day. The more we ignore our natural biology, the more health problems we will have, and at earlier and earlier ages.

Calcium is relatively useless, and may even be harmful, if you do not have adequate levels of vitamin D in your blood. Taking a calcium supplement that is combined with vitamin D is an improvement, although the vitamin D in each supplement is inadequate. However, in order to obtain adequate levels of vitamin D, one would obtain possibly dangerously high levels of calcium and/or other vitamins if taking a multivitamin. The best and safest method of obtaining adequate levels of vitamin D is through appropriate UVB radiation exposure of unprotected skin. Excessive doses of vitamin D via supplementation can create health problems such as kidney stones. Fortunately, you cannot overdose on vitamin D obtained through UVB radiation exposure. Unfortunately, most of us fail to receive enough appropriate exposure to optimize our vitamin D levels.



Once you have completed the worksheet and carefully thought about your answers, you will have some idea of your lifetime exposure to UVB radiation and, consequently, whether your vitamin D levels may be inadequate. You can have a blood test done to determine your exact level at the time of the test, but such tests are uncommon and probably will not be covered by insurance unless you have osteoporosis. If you do choose to have the test done, make sure that the test measures the 25-hydroxyvitamin D (25 OHD) level, not the 1,25-dihydroxyvitamin D (1,25 OHD). The 1,25 OHD level can appear normal to a physician, while the 25 OHD level is actually inadequate. Such a situation is indicative of an out-of-balance vitamin D hormonal system and is associated with health problems.

If you have the 25 OHD level tested, you may want to test it both in February and in August. Vitamin D varies by season, with the highest levels in the summer months and the lowest in late winter. Although many physicians consider any measurement of 25 OHD between 10 and 60 ng/ml to be in the normal range, this is simply because they are using data based on tests done on individuals of European descent who did not appear to have any bone disorder such as rickets, osteomalacia, and osteoporosis. This range was based on prevailing levels in these individuals rather than on those levels required for optimal health. However, recent research has shown that the normal average level of 25 OHD should actually be 40 - 60 ng/ml if we base it on healthy individuals living in equatorial regions, and even higher if we use our wild-living primate relatives as the reference group. Any measurement below 32 ng/ml should be considered inadequate for optimal health. If you choose not to be tested, you can still have an idea of whether your vitamin D levels are adequate or not. If you have light skin color and get less than 30 minutes/day of UVB radiation exposure (between the hours of 10 am and 3 pm during the summer months), or if you have very dark skin color and get less than five hours/day UVB radiation exposure, the odds are that your levels of 25 OHD are inadequate for optimal good health. You can make up the difference somewhat through diet, but as you will see next month when you fill out the second worksheet, Vitamin D Intake, this is quite difficult to achieve.

The second worksheet (see attachment) lists all the food items containing vitamin D either naturally or through supplementation. Dairy and cereal products are supplemented with vitamin D. Eggs contain vitamin D because chickens are fed vitamin D-fortified feed since poultry kept indoors suffer from very high rates of rickets if they do not receive adequate amounts of vitamin D in their diet. The vitamin D is stored in the egg fats. As a point of interest, vitamin D is also added to the food given to primates and other tropical animals housed in zoos in temperate zones in order to prevent rickets.

If you plan to follow the Premiere Nutrition plan (discussed in a future essay) and eliminate all dairy and grain products, your food options for obtaining vitamin D are essentially limited to eggs and cold water fish. If you compare the foods you eat as checked on Vitamin D Intake worksheet with the amount of vitamin D in each of those foods as shown on Table 1, you will find that the best sources of vitamin D are the fish. Eating sardines and salmon provide a quadruple benefit. They a good source of: 1) low-fat protein, 2) omega-3 fatty acids, 3) vitamin D, and 4) calcium (through eating the tiny bones).

Eskimos have a moderate skin color and have lived in the Arctic region for about 5,000 years. This region has the lowest level of available UVB radiation in the world; therefore, you would expect that any groups living there would have very light skin color as do Scandinavians. However, Eskimos have been able to live successfully in this region because they eat at least six times more fish than do those of European descent living in the same regions, thereby providing the Eskimos with high levels of vitamin D. Eskimos who eat a traditional diet have a calcium intake primarily from fish (such as sardines, salmon, and needlefish) and kelp. Those with a mixed diet (traditional and market) get most of their calcium from market foods. Osteoporosis is currently a major problem among Eskimos. It is unclear what role dietary changes have played in this problem. It may be that even a slight decrease in dietary intake of vitamin D from fish, with the fish being replaced by market goods, may be too great when a group of people lives in an environment far different than the tropical environment for which humans evolved. That the key element is vitamin D not calcium is supported by research which found that Finns who had a high dairy intake, but ate little fish, had high rates of rickets compared with those Finns who had a low dairy intake, but ate fish several times per week.

The amounts of vitamin D in each of the foods shown in Table 1 are listed in International Units (IU) or micrograms (mcg). Current Recommended Dietary Intake (DRI) of vitamin D for adults under age 50 is 200 IU or 5 mcg. Previously, the amount was 400 IU or 10 mcg. This is now given as the amount for those aged 50 70. For those over age 70, the amount is 600 800 IU or 15 20 mcg. If you are getting most of your vitamin D through exposure to UVB radiation, the DRI amounts may be fine during the summer months. But if the goal is to achieve a 25 OHD level of 50 ng/ml, the DRI amounts are too low during the winter months, and are especially too low if you are getting your vitamin D through diet. Young adults with light skin color who spend a good portion of the summer outdoors have blood 25 OHD levels of 60 ng/ml. To get such levels through diet or supplementation would require taking 5096 IU or 127.4 mcg of vitamin D3. Currently, efforts are underway to have the DRI raised to more appropriate levels.

The minimum amount of vitamin D you get from your diet or supplementation should probably be 1000 IU or 25 mcg per day. If you live in Canada, or other far northern latitudes, researchers recommend an intake 4,000 IU or 100 mcg per day of vitamin D. If you do not eat the listed fish several times per week [which is not recommended for large fish such as salmon], it is exceptionally difficult to get 1,000 IU or 25 mcg per day of vitamin D from the diet. Obtaining 4,000 IU or 100 mcg (or more) per day from your diet is impossible unless fish are virtually your sole source of protein and/or more than 20% of your diet is in the form of protein. That is, you would need to eat as much fish as do Eskimos when they eat a completely traditional diet. Since most of us will not do that, and since even most Eskimos appear to no longer do that, supplementation is necessary.

As mentioned previously, the best form of supplementation is vitamin D in 1000 IU pills. Research was done which had subjects take 350 mcg (14,000 IU) per day of vitamin D for twelve months; no evidence of elevated levels of calcium was found. Therefore, an intake of 4,000 IU per day should create no problems with calcium. Another point that needs to be stressed when dealing with supplements is that the type of vitamin D used in the supplement needs to be vitamin D3 also called cholecalciferol. The form generally used in North America is vitamin D2 or ergocalciferol, a synthetic variant not produced in animals, including humans. The synthetic form has different biologic properties from vitamin D3 and could be more toxic than the naturally-occurring vitamin D3.



Adequate levels of vitamin D are critical to optimal health. Current standards for what is considered the normal range of vitamin D (25 OHD) are too low at the lower end of the range. A measurement of less than 40 ng/ml of 25 OHD is probably evidence of health problems.

The best method for obtaining adequate vitamin D is the method used for millions of years: appropriate exposure of unprotected skin to UVB radiation. In the temperate zones of North America, this exposure is primarily obtained during the summer months between 10 am and 3 pm. If the natural method is inadequate or not possible, then you can get vitamin D by eating a diet heavy in fish such as salmon and sardines, and/or through supplementation. Current research indicates that the minimum daily dosage of vitamin D through diet and/or supplementation should be 1000 IU or 25 mcg per day. For those living in the more northern latitudes, a dosage of 4000 IU or 100 mcg per day is recommended.

Okinawans have one of the longest average life spans and the largest numbers of centenarians per 100,000 of any population. Some researchers believe this is due primarily to their diet, exercise profile, and low-stress lifestyle. While these all play a role, it is probable that the major key to the good health of their oldest old is the fact that Okinawans are a group whose individuals have light-to-moderate skin color and who live fairly near the Equator at a latitude of 250 N. They spend a great deal of time outdoors gardening and exercising, and are exposed to UVB radiation on a year-round basis. This means that their average blood levels of 25 OHD, if tested, would probably be optimal at 50 ng/mL. The health and longevity of the oldest old on Okinawa probably owes more to their receiving adequate levels of UVB radiation resulting in optimal levels of vitamin D than to their diet, which is grain-based.

Without enough vitamin D in your blood, your health is at risk. It is extremely important that infants, children, adults, and seniors maintain appropriate levels of vitamin D if they are to avoid skeletal problems. Adequate levels of vitamin D may also suppress tumor development in prostate, colon, and breast cancers, and in the skin cancer melanoma. Symptoms of hypertension, diabetes, rheumatoid arthritis, and multiple sclerosis, among other autoimmune problems, are reduced or eliminated by increased levels of vitamin D. Vitamin D is the Key to Optimal Health.


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Copyright 2001-2009 Kathleen E. Fuller, PhD. All rights reserved.