Vegetables and Fruit in the Prevention of Chronic Age-Related Diseases

Brandt, K

doi:10.1016/B978-0-12-801816-3.00050-9

Vegetables and Fruit in the Prevention of Chronic Age-Related Diseases

Lookup NU author(s): Dr Kirsten Brandt ORCiD

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Abstract

• Consumption of vegetables and fruits is clearly associated with a reduced risk of dying from cancer, cardiovascular diseases and diabetes. • The 20% of people with highest intake of fruit and vegetables typically experience 10% lower risk of premature death. This is highly significant, although much less than some other factors such as not smoking. • Not all vegetables and fruits are equal, some types appear to benefit human health more than others. Most likely this means that the substances that are responsible for the health benefits occur in higher concentrations in the most beneficial types of produce. • If we can identify the beneficial substances, it would be feasible to choose the most ‘concentrated’ fruits and vegetables. This would substantially increase the content of these substances in the diet, and could thus provide major health improvements without radically changing the diet. • An old theory (from 1956) suggested that the health benefits of vegetables and fruits could be primarily caused by antioxidant effects, via reduction of the level of free radicals in the body, since this was assumed to protect tissues against damage and thus reduce disease risk. We now know that this is incorrect, since excess free radicals in human tissues are not a general cause of ageing or disease (although can be a consequence of these). Numerous studies have shown that antioxidant effects of food have no benefits for human health, unless the diet is seriously deficient in vitamin C and vitamin E. • In contrast, recent research indicates that a variety of moderately toxic phytochemicals (natural pesticides) may inhibit pathways controlling the ageing process, in a similar way as “caloric restriction,” which is known to extend lifespan. • This knowledge is helping to define a way forward for this research, to design experiments to identify the real beneficial substances among all the different compounds present in the plant foods. • Some of the beneficial phytochemicals have antioxidant effects, but most of them do not. This demonstrates how other properties of these same compounds, such as slowing down the growth and ageing at cell level, are more important for the human health benefits.