Citrus fruit is pretty cheap. However, it has not always been this way. Originally citrus fruits were the food of the rich and access to the benefits of citrus were not available to the poor. However, as efficiencies in agriculture have been found, the availability of citrus fruit has lowered its cost considerably. This is highly beneficial to those of modest income, because citrus fruit may offer protection from the development of cancer.
Citrus is fruit is best known for its content of vitamin C. In fact most people know the story of the use of limes to prevent scurvy in ships, pioneered by the British. Vitamin C may be protective of cancer because it is a very important water soluble antioxidant. The free radical theory of cancer suggests that chronic systemic oxidative stress may cause DNA damage. This in turn may lead to the initiation of cancer. Antioxidants such as vitamin C may therefore protect from cancer.
As well as vitamin C, citrus fruit contains polyphenols. In fact citrus fruit is the only major sourse of the flavonoid sub-group the flavanones. Like vitamin C, polyphenols are important water soluble antioxidants. Therefore like vitamin C they may protect from cancer through inhibition of free radicals. However, polyphenols are also able to regulate gene expression and inhibit enzymes, and in this way they may have multiple mechanisms by which they can inhibit cancer.
Whole Fruit or Juice?
Most people consider fruit juice to be as healthy as whole fruit. However, fruit juice is not the same as whole fruit. In whole fruit, the sugar is contained within the cells, encapsulated by tough cell walls. When juice is made this sugar is released into solution. The upshot of this is that sugar from juice is absorbed more quickly and this causes the liver to become overloaded with nutrients. Eating whole fruit slows this process and is a far healthier alternative.