Plants synthesise a number of phytochemicals that are bioactive in humans. Some of these phytochemicals may reduce the risk of cancer if consumed regularly. Plants also contain minerals. Some of these minerals are required for correct metabolic function in humans. Eating plants absent of these important minerals can therefore increase the risk of cancer. Here is a list of 5 nutrients found in plants that may be particularly protective of cancer.
Selenium is a cofactor for the cellular antioxidant enzyme glutathione peroxidase. This enzyme is able to protect cells from oxidative stress and is sometimes referred to as the primary antioxidant in humans. Low intakes of selenium in the diet decrease glutathione peroxidase activity and this increases oxidative stress, a possible cause of cancer initiation. A study giving 200 micrograms of selenium per day to deficient subjects caused a reduction in cancer mortality by 50 %.
2. Green Tea
Green tea is a decoction made from the Camellia sinensis plant. Brewing the leaves for 5 minutes in boiling water produces a drink with high amounts of plant chemicals called catechins. These catechins are protective of cancer, especially cancer of the gastrointestinal tract. Because green tea may protect from carcinogens in food, it is advisable to drink green tea with each meal, as is the custom in Asian countries such as Japan.
3. Garlic And Onions
Garlic and onions contain sulphurous compounds that may inhibit cancer. The compounds are not found in the original plant material, but are created upon crushing, cutting, chewing or cooking. The chemicals released from this process are numerous, and their chemistry complex. However, regular consumption of these foods decreases the risk of cancer. This may occur through increased detoxification of carcinogens as well as a direct toxic effect on cancer cells.
The ability of turmeric to kill cancer cells in test tubes is well established. Epidemiology also suggests that those who consume turmeric have a lower risk of cancer. Turmeric is able to prevent cancer because the curcumoids in the spice can inhibit the growth of new blood vessels that are needed for cancer progression and may also protect DNA by inhibiting oxidative stress. Turmeric also has anti-oestrogenic properties that may explain its anti-cancer effects.
5. Brassica Vegetables
Brassica family vegetables include broccoli, cauliflower, sprouts, watercress and kale. These vegetables contain glucosinolates, that are converted upon chewing to isothiocyanates and indoles. Both isothiocyanates and indoles are able to decrease the rate of conversion of chemicals into carcinogens in cells, and at the same time increase the rate of conversion of carcinogens to harmless metabolites. In this way they limit the exposure time of tissues to carcinogens.