Holistic health care providers have long insisted that we may need much higher amounts of various vitamins and minerals to maintain health or recover from illness than the U.S. "recommended daily allowance" suggests.  The R.D.A.s were developed by looking at what levels of intake would prevent "index diseases," the diseases of frank deficiency (i.e., scurvy in the case of vitamin C, rickets in the case of calcium) in a healthy adult.   Of course, who counts as a healthy adult is in itself a big question.  First of all, most of the R.D.A.'s were set using men as models.  Second, the R.D.A. process assumed that anyone who did not present with frank, allopathically-recognized pathology was healthy.  

Anyone who has suffered or watched a loved one suffer from a chronic functional disorder (like fibromyalgia, osteo- or other arthritis, premenstural syndrome, non-ulcer dyspepsia, sleep apnea, or irritable bowel syndrome) knows that the absence of frank pathology definitely does not equal health!  What we may not recognize is that these seemingly "minor" afflictions are functionally related to the chronic diseases that are the biggest killers here in the West: cardiovascular disease, diabetes, and cancer.   All of these chronic diseases are influenced by nutritional status (among other factors), but it can take many years--decades even--for nutritional deficiencies to result in discernible dysfunction or disease.  These diseases, therefore, are called "long latency diseases."

The R.D.A. also does not take into account the fact that different individuals have different requirements for different nutrients, as well as different abilities to absorb them from foods.  These differences among individuals are related to our genetic uniqueness and to the ways our interaction with our environment has effected the expression of our genetic potential.  And because we are always dynamically responding to a changing environment, our needs for different nutrients vary over different periods of our lives.  It is obvious, then, that the static formula set out by the R.D.A. is utterly inadequate for assessing our individual need for nutrients.

Happily, in recent years conventional science has begun to catch up with traditional holistic wisdom in this matter.  As one author put it in the American Journal of Clinical Nutrition in 2003, "Because the intakes [of nutrients] required to prevent many of the long latency diseases are higher than those required to prevent the respective index diseases, recommendations based solely on preventing the index diseases are no longer biologically defensible." (Heaney, Robert P. "Long-latency deficiency disease: insights from calcium and vitamin D1-4," Am J Clin Nutrition 2003; 78: 912-9.)  Better late than never!

In recent years, there has been a spate of articles in the literature about the importance of vitamin D and about its widespread deficiency in populations, especially populations at high latitudes (that's us, folks).  Vitamin D deficiency has been linked with arthritis, joint and muscle pain, and mood and behavioral disorders.   Other clinicians and researchers have long questioned the involvement of vitamin D deficiency in multiple sclerosis, which is vastly more prevalent at higher latitudes than at equatorial regions.  (When people from equatorial regions move to higher latitudes, their risk of developing MS comes to equal that of the local population within one generation.)  

The most recent scientific recommendations suggest that in the absence of exposure to sunlight (and most of us barely have any exposure to sunlight even in the summer months because our jobs require us to spend so much time indoors), a daily intake of at least 1000 I.U. of vitamin D3 is required to maintain a healthy concentration of this nutrient in the blood.  (Check it out--does your diet routinely provide you with 1000 I.U. of vitamin D?  Mine sure didn't, even when I was remembering to take my teaspoon of cod liver oil daily, and cod liver oil averages 400 I.U. per teaspoon.)  Of course, if you are already deficient in vitamin D, you may require much higher intake for a while in order to bring yourself back up to normal levels.

What is a normal level?  Experts in the field agree that a concentration of 25-hydroxyvitamin D3 between 50 and 75 ng/ml is healthy.   Any physician, including your chiropractor, can order this test for you--however, if you have health insurance, it is more likely to pay for the test if it is ordered by an M.D. or naturopathic physician (N.D.) (if you live in Vermont).   Even if you don't suspect deficiency, it's worth asking for this test if you're having blood work for some other reason.  Many of my clients have been surprised to see just how low their vitamin D levels were--and how much better they felt as their levels came up with supplementation.