ChiroACCESS Article



The Implications of Vitamin D Insufficiency in a Chiropractic and Wellness Practice



This information is provided to you for use in conjunction with your clinical judgment and the specific needs of the patient.

Dwain M. Daniel, D.C.

  

Parker College of Chiropractic Research Institute



Published on

October 12, 2009

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Introduction

As the chiropractic profession moves into the 21st century a renewed emphasis is being placed on the concept of the wellness practice (1). This paper addresses the evidence relating to vitamin D (ViD) in the prevention of many serious health conditions as well as its role in conditions which confront the chiropractic physician on a daily basis.

Ancient man lived in hunter-gatherer societies. His diet consisted of what was gathered from his environment or game he could kill. Dietary sources of ViD were limited and sun exposure to a nude or semi-nude body was the primary source of ViD. As mankind moved into an agricultural and then into an industrial society, polluted skies, sunless cities and clothing severely reduced sun exposure. Lack of ViD production in the skin resulted in growing numbers of cases of rickets in industrialized cities. In 1822 the relationship between rickets and the lack of sunlight was first reported but the information was not widely utilized. By 1909 rickets was epidemic. Over 80% of city living children, dying of other causes, manifested signs of rickets (2). In the 1920’s the curative effects of ultraviolet (UV) light, specifically ultraviolet B (UVB), and ViD were recognized (3). In the 1930’s milk was fortified with ViD and rickets soon became a rarely encountered condition in the United States (4).

The history and reputation of ViD is based on its role in the prevention of rickets and bone health. On the surface ViD appears to be a rather mundane nutrient. The recommended daily allowance (RDA) is set at a modest 200 international units (IU) per day and a couple of glasses of ViD fortified milk will fulfill that requirement. If there are any additional needs for ViD the skin can synthesize it from UVB produced by sunlight. It all seemed rather uncomplicated, at least until the 1970’s and 80’s.

Between 1975 and 1985 the incidence of melanoma in the United States increased by 5.6% per year according to the National Cancer Institute (5). This increase was strongly associated with overexposure to UV rays found in sunlight (6-9). In an effort to reverse this trend sun avoidance guidelines were established by governmental agencies and medical authorities (10-12). These efforts appeared to be at least partially successful as between 1985 and 2006 the rate of increase had fallen to 2.9% [4]. Ironically, at approximately the same time sun avoidance programs were being developed and implemented, the association between reduced circulating ViD and serious health consequences were being recognized (13-19).

Review

There are 32706 published articles listed in Pubmed using the medical subject heading (MeSH) term vitamin D. The sheer volume of articles precludes a systematic search when writing a review that represents an overview of the use of ViD in the prevention and treatment of many varied conditions. The author has attempted to provide a balanced overview that provides the positive findings related to ViD as well as the negative findings.


Sources and optimal daily dose of ViD

In the 1970’s and early 1980’s circulating levels of 25-hydroxyvitamin D [25(OH)D] became an accepted measurement of ViD status (20-22) and is now considered the standard measurement. Results are commonly reported in ng/ml or nmol/L (1 ng/ml=2.5nmol/L).

The optimal level of circulating 25(OH)D is a matter of ongoing debate. Many experts now recommend 30ng/ml (75 nmol/L) as the lower limit of 25(OH)D (23-25). Others recommend 32 ng/ml (80 nmol/L) (26-28) while still others place the lower limit at 40ng/ml (100 nmol/L) (29-31). An interesting study done in 1971 compared levels of 25(OH)D in lifeguards and “normal” volunteers. Lifeguards had mean levels of 64.4 ng/ml while “normals” had mean levels of 27.3 ng/ml. Some interpret these findings to mean that the lifeguards, since their sun exposure came closer to ancient man’s exposure, were in fact the normals while the “normals” were actually deficient (32).

According to the National Health and Nutrition Examination Survey (NHANES), 2000-2004, over 70% of Americans have levels of 25(OH)D that are below 32 ng/ml (80nmol/L) (33).

Supplementation

Circulating levels of 25(OH) D are based on numerous variables. Among these are skin color, season, latitude, age, sunscreen use, supplement use and obesity (34). In order to determine the amount of supplementation necessary to maintain a desired level of 25(OH)D, a baseline must first be established. According to estimates provided by Hollis, in order to raise baseline levels 7 ng/ml (17.5 nmol/L), supplementation of 1000 IU daily is required. Ninety days of supplementation is necessary before levels stabilize. Continued supplementation is required to maintain levels (35).

Although the upper safe limit for ViD established by the Office of Dietary Supplements is 2000 IU daily (36), most experts consider this dosage unreasonably low. One author even suggests 2000 IU should be the RDA rather than the upper limit (37). Numerous studies and expert opinion recognize an upper safe limit of 10,000 IU (38-45).

Sunlight

SunlightWhen the skin is exposed to sunlight, specifically ultraviolet B (UVB), 7-dehydrocholesterol is converted to previtamin D1 which in turn is converted to vitamin D3 (46). This is a very efficient source of ViD production and is the primary source of ViD for most people. Young, light skinned individuals can produce 10000 to 20000 IU of ViD when receiving 1 minimal erythemal dose (MED) of sunlight when wearing a bathing suit (A MED is defined as the exposure to sunlight that will cause slight pinkness of the skin). In contrast a dark skinned individual exposed for the same amount of time will not show any increase (47). Holick estimates exposure of ¼ MED over 20% of the body (hands, face and arms) will provide 1000 IU of ViD. The time of year, time of day, skin color, latitude, age and atmospheric conditions all impact on the amount of time necessary to produce ¼ MED. For example, above 35° latitude (Atlanta, Georgia) between November and February there is insufficient UVB available to produce ViD (48). A paper written by Webb and Engelsen outlines the amount of time individuals with different skin types must spend in the sun at noon, at different latitudes, at different times of the year and different atmospheric conditions to receive 1000 IU of ViD. They note a fine line exists between an adequate amount of sunlight necessary to produce ViD and sunburn (49). A web site has been developed based on this paper that allows an individual determination of required time based on the variables noted above. This information is available at http://nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html (50).

Tanning Centers

Many individuals consider tanning beds a good source for ViD. There are up to 50000 tanning facilities in the United States (51). The dominant ray used in tanning beds is ultraviolet A (UVA). A cross sectional study of 50 tanning facilities in North Carolina demonstrated tanning beds produce almost 5 times as much UVA as noon sunlight in the summer in Washington, D.C. and almost 2 times the amount of UVB. Levine et al. estimate tanning salon patrons receive between 4.5 to 7 times the UVB radiation necessary to synthesize ViD (52). The harmful effects of excess UVA and UVB have been well documented (6;53-57). Several observational studies have related tanning bed use to increased risk of various skin cancers (58-62). Additional research must be conducted before the safety of using indoor tanning to produce ViD can be fully evaluated.


Disease and Vitamin D

In the late 1930’s and early 1940’s observational studies noted a relationship between sunlight and cancer. Peller and Stephenson observed the skin cancer rate in the U.S. Navy was 8 times the normal rate but deaths from other cancers occurred at 40% of the normal rate (63). Apperly in his observational study stated “cancer mortalities …are shown to fall with increasing solar radiation” (64). Interest in the role of ViD and sunlight was reignited by Garland and Garland in 1980 when their Lancet article presented the observation that colon cancer rates were inversely associated with ViD and sunlight (9). Since then a large body of observational and epidemiological evidence has found a relationship between low levels of ViD and a variety of disease conditions. A 2007 meta-analysis of 18 randomized controlled trials (RCT) consisting of 57311 participants found a mean intake of only 538 IU of ViD reduced all cause mortality by 7% (65). As of 2007 17 ViD sensitive cancers have been identified. According to Grant, Garland and Gorham supplementation of 1000 IU of ViD would reduce all cancer mortality rates 10 to 20% in the United States and western Europe (66).

Cancer

Since Garland’s study in 1980 (67) interest in the relationship between ViD and cancer has grown. Most studies are observational but strong relationships have been established using large populations. Giovannucci et al. estimated by increasing 25(OH)D levels 10 ng/ml (25nmol/L) there would be a 20% lower mortality rate from cancer resulting in 85550 fewer cancer deaths yearly in the United States (68). A RCT following 1179 female patients (>54 years old) over a 4 year period found a combination of 1500 mg of calcium and 1000 IU of ViD reduced the risk ratio of developing cancer after the first year of the study to 0.232 (CI:0.09-0.60) (69).

The strongest correlations of high levels of 25(OH)D appear between ViD levels and colorectal and breast cancer.

A 2009 meta-analysis using 8 nested case-controlled studies of 3556 patients concluded an increase of 8 ng/ml (20 nmol/L) in 25(OH)D would reduce risk of rectal cancer 59% and colon cancer 22% (70)-60]. A second meta-analysis from 2007 concluded a serum 25(OH)D level of greater than 33 ng/ml would reduce colorectal cancer risk by 50% (71).

A case control study of 3919 post menopausal patients with 17093 controls found, when compared to the lowest category (13.64 ng/ml), the highest category (30ng/ml) had a odds ratio of developing breast cancer of 0.31 (CI: 0.24-0.42). These results were essentially repeated in a 2009 study of 1026 cases and 1075 controls using 40 ng/ml as the highest category (72). In 2009 the results of a prospective study which followed 512 women with early breast cancer for 7 years was published. Mean age of the study population was 50.4 years. Women that were deficient in ViD levels had an increased risk of distant reoccurrence (hazard ratio (HR)=1.94;1.16 to 3.25) and death (HR=1.73; 1.05-2.89) compared to women with sufficient levels (28.8 ng/ml or 72 nmol/L). These results were modestly attenuated in multivariate analysis. The authors suggest the optimal levels of 25(OH)D to be 32 to 44 ng/ml (80 to 110 nmol/L) but caution against attaining higher levels until additional research is completed (73).

Multiple Sclerosis

The first associations between sunlight and multiple sclerosis (MS) were made by Kurtzke in 1977 (74). Others have found similar relationships (75;76). A prospective, nested case-control study from a population of 7 million U.S. military personnel selected 257 patients with MS with 2 matched controls each. The authors concluded high levels of 25(OH)D were associated with a lower risk of MS (odds ratio of highest quintile to the lowest =0.38). The study found the inverse relationship was only valid among whites. Levels of 25(OH)D in blacks and Hispanics in this study were significantly lower which prevented quantile analysis (77). Another study analyzed the findings of the Nurses Health Study (n=92253) and the Nurses Health Study II (n=95310) and found women who used ViD supplementation, median of 400 IU/day, had a reduction of 40% in risk of developing MS (78). It should be noted that a 2009 study associated low levels of 25(OH)D and MS in women only (79).

Pain

An intriguing yet controversial topic for the chiropractic physician is the limited evidence associating chronic pain to insufficiency of ViD. A small RCT in 1981 of 22 women with backache and compression fractures found a combination of sodium fluoride, calcium and ViD provided statistically significant pain relief after 12 weeks (80). Subsequent observational studies demonstrate low levels of 25(OH)D are associated with wide spread chronic pain (81-83). A small case series of 6 patients with chronic back pain or failed low back surgery reported complete resolution of back pain in 4 patients within 6 weeks. Dosage of ViD was between 2000 and 5000 IU/day. The 2 remaining patients improved but not completely (84). A larger case series, examining 128 statin treated patients with muscle pain, found 92% of the patients treated with 50000 IU/week for 12 weeks were pain free at the conclusion of the study (85). As encouraging as the studies mentioned above may be, there is other evidence that is not as encouraging. A 2009 review article examining 22 relevant studies found lower quality studies established a relationship between pain and low ViD levels while the 5 studies which were RCT’s did not. Overall the authors concluded there is insufficient evidence to conclude ViD is useful in the treatment of chronic pain while acknowledging there is a “beguiling attraction” to the hypothesis (86).

Pregnancy and Early Life

Although the impact of ViD insufficiency on the health of children beyond rickets is not fully understood, the presence of insufficiency is well established (87). A study of 84 unsupplemented, breastfed infants in Iowa found 10% were ViD deficient during the summer and 78% in the winter. Dark skinned infants were the most effected (88). In a review by Lucas et al., low VID status of either the pregnant mother and newborn may be related to shorter gestation, lower birth weight, multiple sclerosis, Type I diabetes and asthma (89). Some experts suggest pregnant or lactating mothers should supplement with at least 2000 IU of ViD (90;91). The relationship between asthma and ViD is particularly interesting due to conflicting results in different studies. Gale et al. found children of mothers whose 25(OH)D were over 30 ng/ml (75nmol/L) late in pregnancy had an increased risk of asthma at 9 years old (OR 5.3; 1.09-25.65) (92). Other studies have found an opposite, inverse relationship between ViD status and asthma (93-96). Lucas et al. speculated it may be a question of timing. High levels during pregnancy may be protective during the early stages but should not be maintained in the late stages. This observation is consistent with the findings of Hypponen et al. who suggested optimum levels should be between 30 and 40 ng/ml (75-100 nmol/L) as low or high concentrations may trigger increases in IgE (97). Obviously additional research is required before firm conclusions can be drawn. Investigations are still preliminary but the potential importance of ViD in fetal development and in early life clearly warrant additional research efforts.

The Immune System

Although excess UV rays are acknowledged to suppress the immune system (98), there is emerging evidence that ViD may play an important role in ViD-mediated immunity (99-101). Relationships have been established between circulating ViD and respiratory infection (102-104), sinusitis (105), periodontal disease (106) and autoimmune disorders such as rheumatoid arthritis, Type I diabetes and multiple sclerosis (107;108).

Other Conditions

Some relationships may be weak or level of evidence low but as the interest in ViD has continued to increase over the last decade, the number of conditions that may be related to ViD has also increased. The following list of conditions, which is likely incomplete, have been related to ViD insufficiency; hypertension (109;110), metabolic syndrome (111), fibromyalgia (112), dementia (113), cardiovascular disease (114;115), insulin resistance (116) premenstrual syndrome (117), depression (118;119), knee cartilage loss (120) and cognitive performance in older men (121).

This monograph has several limitations. A systematic search of the literature was not performed and author bias may be reflected. The reader should also be aware although there is a mountain of observational studies, there is a dearth of RCTs. Many explanations can be used for the relationship between ViD and health. Higher levels of ViD and positive health outcomes may be related to increased outdoor activity. Outdoor activity usually indicates a more active individual and the health benefit may come from activity not ViD. It is also possible individuals that supplement with ViD are generally more health conscious and would expect to have better overall health outcomes. Additional high quality RCT’s are necessary to fully understand the role of ViD in health.


Conclusion

When one searches the scientific literature the amount of information on ViD is truly overwhelming. Unfortunately the lack of high quality studies is disappointing. Consequently a small leap of faith is required to confidently recommend ViD to patients to prevent and sometimes treat a myriad of illnesses. However when considering the low cost and low risk of ViD compared to the great potential returns, recommending ViD becomes less difficult. One can take comfort in recognizing although correlation cannot equate to causation, causation cannot occur without correlation.

In conclusion the health benefits, particularly when considering the cost/benefit/risk ratio, is very favorable to ViD. Prudent sun related activities rather that sun avoidance should be encouraged and individuals should supplement based on their baseline 25(OH)D levels. The result could be a wellness practice that actually has healthier patients.
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