Vitamin C deficiency causes scurvy, a deadly disease where the blood vessels of the body disintegrate. In my previous article (here) I discussed the inverse relationship between vitamin C intake and blood histamine levels, and the protection vitamin C may give to the vascular system by inhibiting histamine production and relaease. In addition to protecting the cardiovascular system, vitamin C has been shown to decrease the severity and frequency of colds, provides general antioxidant defence and also decreases the exposure of the gut to carcinogenic chemicals such as nitrosamines. Vitamin C is present in foods (figure 1), but studies have shown variability in levels. This makes it difficult to determine intakes from food records. Because of the uncertainty surrounding vitamin C in the diet, supplementation is recommended. However, the number of supplements on the market can make the choice confusing.
Figure 1. The total vitamin C content of various fruits. Total vitamin C refers to the ascorbic acid plus the dehydroascorbic acid. Adapted from; Szeto, Y. T., Tomlinson, B. and Benzie, I. F. F. 2002. Total antioxidant and ascorbic acid content of fresh fruits and vegetables: implications for dietary planning and food preservation. British Journal of Nutrition. 87: 55-59
With most things in life, you get what you pay for. However, vitamin C is probably an exception to this rule. Ascorbic acid is a very cheap chemical manufactured from glucose with a very high yield. Manufacturers press ascorbic acid into tablets along with some binders and fillers (e.g. magnesium stearate, calcium carbonate, silicon dioxide) and sell these tablets to supplement companies in bulk. The supplement companies then put a label on the bottles and sell the tablets to the public. Most supplements have the same ingredients and so paying more for your vitamin C is pointless. Absorption of vitamin C is generally very good and studies have shown that blood levels are directly related to amount of vitamin C ingested. Tablets are usually sold in 500 or 1000 mg doses and >3000 mg per day is recommended.
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