Just What Are Your Optimal Levels of Vitamin C Intake?

Amongst the general public today, vitamin C is probably the most popular of all nutritional supplements, perhaps principally because it is widely believed to be effective as a cure for the common cold. But there is much more to the nutrient than this, as was demonstrated by the celebrated Dr Linus Pauling, whose pioneering work hailed optimal intakes of vitamin C as a powerful weapon against flu, heart disease and even cancer.

Pauling's books became extremely popular, but it almost goes without saying that the medical establishment was quick to ridicule his ideas and still largely refuses to recognise the value of large doses of vitamin C. Not that either the public or Pauling, a double Nobel Laureate, seemed to care much. He regularly took doses of well in excess of 1,000 mg daily, and was working almost until the end of his incredibly active 93 year life.

As well as the happy coincidence of Pauling's longevity, if coincidence it is; a great deal of research now supports his claims for vitamin C, as well as recognising it as one of nature's most powerful anti-oxidants and anti-ageing nutrients. But despite this, the Recommended Dietary Allowance (RDA) remains set at just 60 mg; and, more worryingly still, research suggests that around a quarter of people in the affluent western world, including America and the United Kingdom, manage to consume only about 40 mg of vitamin C a day, just 2/3rds of this already very low RDA.

Despite repeated lectures from government and health agencies to eat five portions of fruit and vegetables a day, it seems that many people still do not do so. And even for those who do, the amount of vitamin C yielded from these foods, grown as they are on nutrient depleted soils, is likely to be low; and will be depleted further by pesticides, transport, storage, processing and cooking.

And as if this were not enough, vitamin C is used up easily once in the body; both by combatting the free radicals released by normal oxidative biochemical reactions and by the toxic stresses produced by environmental pollution. The use of alcohol, tobacco and other drugs, including common medications, is also highly destructive of vitamin C.

Given all these factors, it's hard to think many of us are getting optimal levels of vitamin C, an observation that's strongly supported by a look at intakes in the animal kingdom.

What particularly interested Pauling was that human being are unusual, though not unique, amongst animals in that we are unable to manufacture vitamin C within our bodies. Little in nature is ever wasted, and Pauling argued, logically enough, that animals which do manufacture their own vitamin C would only make as much as their health demanded. It seems, however, that most animals produce around 30 mg of vitamin C per kilo of body weight, and this figure rises dramatically when the organism is under particular stress. For an adult human weighing, say, 75kg (165 pounds), the figure of 30 mg would equate to a vitamin C requirement of 2,250 mg, which of course must be obtained from the daily diet or through supplements.

But in case this figure seems high, it is fortunately possible to compare typical human intakes with those of closest genetic relatives in the animal kingdom, the great apes, who are also unable to synthesise vitamin C within their bodies. Interestingly, the diets prepared for chimpanzees and gorillas in captivity, presumably with their optimal health as the intention, seem typically to yield between 20 and 30 mg of vitamin C per kilo of the animals' bodyweight. And a 1940s study of gorillas in the wild estimated a vitamin C intake from their food of around 4,500 mg, typically around 22.5 mg per kilo of the animal's bodyweight. And of course, it needs to be remembered that these creatures in the wild are likely to be subject to far less environmental stress and fewer toxins than human beings, thereby making better use of the larger amounts of vitamin C they consume, and further emphasising the inadequacy of most human's intakes.

In the face of all this evidence, given that humans are estimated to be around 98% genetically identical to the great apes, an intake of 1,000 - 2,000 mg a day for a typical adult would not seem excessive; and the RDA, in fact, appears pitifully low.

Happily, these optimal intakes of vitamin C are easily achieved through supplementation, and there are no known problems of toxicity at any level. But it is probably best to stagger the intake of high doses through the day, to maximise absorption and maintain saturation levels in blood and tissue at all times.