Recommended dietary allowance: support from recent research.

Increasing evidence is accumulating that a synergistic role of the so-called antioxidant vitamins (C, E, beta-carotene) may have a dominant role in the prevention of cancer, cardiovascular diseases and cataract formation. Controversy still exists regarding the optimum intake of vitamin C. This is partly due to lack of accurate and easily accessible health-relevant end-points, and lack of knowledge of the role of vitamin C in biochemical functions. Today, it is clearly recognized and broadly accepted that optimal health is a consequence of dietary optimization. Attainment of optimal health rather than prevention of deficiency symptoms is the goal. There can be little doubt that in this respect the requirements for vitamin C are greater than the amount required for the mere prevention of overt or classical scurvy. The recommendation of varying levels of requirement could overcome the controversy. The following is therefore proposed: The lowest level is that value which prevents deficiency symptoms. The second level is valid for healthy populations (< 200 mg/d). This level would take into account needs which differ according to age, sex, physical activity, physiological status (e.g. pregnancy or lactation) and environmental factors such as smoking, pollution and alcohol intake. Finally, a third level should be determined for the prevention of the above-mentioned non-communicable diseases. These diseases are an important cause of disability, resulting in costs of billions of dollars annually in medical costs. Many of the above-mentioned diseases can be prevented by supplementation with vitamin C. Medical costs could thereby also be dramatically reduced.