Do the RDA’s (recommended daily allowances) have any relevance?

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Whilst I am an ardent advocate of nutritional medicine, my career in the area was almost snuffed out before it began. Just as my interest in the subject was burgeoning, I found myself aghast at what seemed to be the excessive quantities of nutrients recommended by many natural health experts. Compared to the gold standard RDAs (recommended daily allowances) I had learnt at medical school, it occurred to me that individuals were often being advised to take super-stratospheric levels of vitamin and minerals. I was regularly reading recommendations for people to take 10 or more times the RDA for nutrients such as vitamins C and E. I did wonder what purpose this super-dosing might serve, other than making very expensive urine, that is.

For the last half-century, the RDAs for vitamin and minerals have formed the basis for conventional nutritional wisdom. The commonly held belief is that as the RDAs are met, our nutritional needs will be amply covered. However, as I delved deeper into the subject of nutrition, it occurred to me that the RDAs are little more than an nutritional white elephant. Research over the last decade or two shows that the RDAs are set too low, and have little if any place in modern nutritional dogma.

The RDAs actually represent the level of nutrients needed to prevent deficiency diseases and maintain normal nutrition. For instance, 60 mg of vitamin C is deemed to be the amount of this nutrient we need to consume each day to keep us from getting scurvy. However, the RDAs can be open to misinterpretation. One common misconception about them is that they in some way represent what are deemed to be the ‘safe’ levels of nutrient intake. Actually, the RDAs are not designed to reflect safe nutrient levels at all. What is known to be the safe daily intake for a nutrient is often many times the RDA. For instance, while the RDA for vitamin B6 is just 2 mg, its upper safe limit is at least 200 mg. Another example is vitamin B12, which has an RDA of 1 mcg and an upper safe limit of at least 500 times this amount.

While the RDAs represent the nutrient which is enough
The RDAs do not reflect the level of intakes shown to reduce the risk of chronic illness. For instance, two large studies published in the New England Journal of Medicine in 1993 demonstrated that supplementing with 100 IU of vitamin E for at least two years reduced risk of heart disease in both men and women by 37 – 41 per cent. However, the RDA for vitamin E remains at a measly 14 IU. There is a big difference between the amount of a nutrient needed to prevent an obvious deficiency, and the amount required to maintain optimum health. For example, the RDA for vitamin C is 60 mg. Vitamin C is in fact one of the most important nutrients in the human diet. High intakes of this vitamin have been correlated with a reduced risk of heart disease and cancer, and there is good evidence that supplementing with vitamin C can increase longevity too. Vitamin C also participates in many everyday processes including immune function, detoxification and skin healing. However, it is simply not possible to obtain maximum benefit from vitamin C at the RDA level. More and more evidence suggests that for optimum health, each of us should be consuming at least 200 mg of vitamin C each day, and it may well be that much higher levels (typically several grams per day) are required for peak health and during illness.

Currently, RDAs exist for only 18 vitamin and minerals. Yet, it is well established that we require 50 or 60 nutrients to sustain life. Even if we set this figure much more conservatively, it is clear that several key nutrients are omitted from the RDA system. A good example is the trace mineral selenium. This antioxidant nutrient has been linked with a reduced risk of chronic illnesses such as cancer. A study published in the New England Journal of Medicine in 1996 showed that supplementing with selenium at a dose of 200 mcg per day over a four-year period effectively halved an individual’s risk of dying from cancer. And yet, to this day, no RDA for selenium exists. Other key nutrients for which no RDA exists include beta-carotene, chromium, copper and manganese.

There seems little doubt that the RDAs are, for the most part, outdated, inappropriate, and well overdue for review. What appears to be needed now is a new system of nutritional assessment which reflects the true nutrient level required for safe, effective health maintenance and disease prevention. Increasingly, nutritionists and scientists are now placing more emphasis on ascertaining the levels of nutrients required to truly enhance health, safely and effectively. Quite simply, there is a good case for throwing out the RDAs, and replacing these with higher levels, maybe referred to as optimum daily allowances (ODAs), which reflect the nutrient amounts needed to maintain peak health and prevent illness.

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