Page 33 - Summer 2017 Journal

the quantity of vitamin D our bodies make. Age is a factor too; adults older than seventy need about three times the duration of sun exposure to produce the same amount of vitamin D as children. Non-solar sources of vitamin D are essential in these cases, just as populations living near the poles consumed vitamin D-rich foods as part of their native diet: the organs of ocean fish especially the liver and the fish liver oils, and seal oil and whale blubber (also rich sources of vitamin A!).11
HOW MUCH VITAMIN D?
What amount of oral vitamin D is required
when sun exposure is inadequate? Clearly, many individuals are less able to obtain vitamin D from sun exposure, and modern low-animal fat diets do not provide much naturally occurring vitamin D.12 Following today’s conventional approach of paying attention to only vitamin D intake, this problem appears to be fairly simple to address: use the results of the most recent blood test, supplement accordingly, then retest and adjust the dosage as needed. Selecting a blood level of 25(OH)D to target then becomes the first decision—not always so straightforward though. For example, if the result is between 20-30 ng/mL, this is, according to the Institute of Medicine, “sufficient,”13,14 according to the Endocrine Society “insufficient,”15 and accord- ing to the Vitamin D Council “deficient”16 (see chart below). Interpreting the tests depends on which health agency a practitioner or individual relies upon.17
The next step would be to choose a dose of vitamin D that is both safe and effective. As stated before, it is common to prescribe or
recommend supplementation when a patient’s levels are below 30 ng/ mL, in accordance with guidelines from the Endocrine Society and the Vitamin D Council. Some practitioners may choose to be conservative with a dose of 1,000 IU per day, especially if they don’t expect routine follow-up visits or testing by their patient; 2,000-4,000 IU per day might be chosen if the patient tests below 30 ng/ml and does not get adequate sun exposure; 5,000-10,000 IU per day or more for short term or if the patient will be retested in a few months; even up to 10,000 IU long term, which according to the Vitamin D Council, should not present a risk of toxicity. Rule-of-thumb supplementation has been suggested as follows: to raise serum 25(OH)D by approximately 1 ng/mL, supplement with 100 IU oral vitamin D daily. However, individual responses to standard dosages often vary considerably18 – several caveats are discussed below.
DESIRABLE VITAMIN D LEVELS
Despite a lack of consensus, what appears to be a desirable vitamin
D level? Vitamin D, in the activated form of 1,25(OH)2D, acts on many different cells in the body both through calcemic roles, regulating calcium and phosphate concentrations, and noncalcemic roles. Noncalcemic roles include cell differentiation and antiproliferative actions in a wide range of cell types such as the immune, muscle and gastrointestinal systems.19 Research has shown inverse associations between vitamin D levels (re- gardless of sun exposure) and the incidence of several diseases, pointing to roles in the prevention of heart disease, cancer, diabetes, autoimmune disease, neuromuscular impairment and more.20 The evidence to support an optimum range of serum 25(OH)D for health outcomes is strongest when considering the impact of vitamin D on bone health.13 Calcium homeostasis is achieved by the influence of 1,25(OH)2D on calcium absorption, uptake and release from bone tissue and excretion from the kidneys. Adequate levels of 25(OH)D are needed to ensure adequate synthesis of 1,25(OH)D, important for bone mineralization and general muscle and bone health. Severe vitamin D deficiency can result in hy- pocalcemic seizures and weak or misshapen bones—rickets in growing children, osteomalacia and osteoporosis in adults.
According to expert opinions, the minimum level of serum 25(OH) D needed for bone fracture prevention ranges between 20-32 ng/mL with desirable 25(OH)D concentrations between 28-32 ng/mL. It is estimated
VITAMIN D FROM SUNLIGHT
Masterjohn has described the practices of healthy pre-industrial societies regarding sun exposure including seek- ing shade in the midday and using a variety of methods to protect the skin when in the sun, such as primitive forms of sunscreen like coconut oil, body paint and protective clothing. He has also discussed findings which indicate that genetic adaptations direct an increased synthesis of vitamin D in northern indigenous populations, and conversely, an increased degradation of vitamin D in southerly populations.
Indigenous populations are innately adapted to their native climate, allowing their bodies to better control vitamin D production in accordance with their needs. Furthermore, his analysis of the evidence indicates that it does not support the conclusion that levels of 40-60 ng/mL for vitamin D are “natural;” people outside of tropical and subtropical regions may not be genetically adapted to having vitamin D levels so high.
SOURCE: http://www.westonaprice.org/our-blogs/cmasterjohn/vitamin-d-problems-with-the-latitude-hypothesis/.
SUMMER 2017
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