How Do Dietary Antioxidants Really Work?

By Robert Smith*

24 July 2018 (Wall Street International)* — Inflammation can be one of the most misunderstood aspects of health when viewed with reductionist thinking. Part of the misunderstanding is based on the assumption that model organisms, such as baker’s yeast (Saccharomyces cerevisiae), the fruit fly (Drosophila melanogaster), mice, rats and dogs can tell us what also happens in humans.

That is, caloric restriction without starvation has extended the lifespans of these organisms. This idea was based on the assumption that restricting the consumption of total calories would lower the total metabolic rate and the production of reactive oxygen and nitrogen species (RONS) as well as free radicals.

This led to the free radical theory of aging, in which it was proposed that the accumulation of damage caused by free radicals causes aging and eventually death. That is, the oxidative metabolism of proteins, fats and carbohydrates in the mitochondria in cells produces RONS and free radicals, which can oxidize and damage DNA, lipids and proteins.

This can lead to autoimmune diseases and cancer as well as cardiovascular and neurodegenerative diseases. So, people in almost all countries were encouraged to eat foods that have a high antioxidant capacity. Also, artificial in vitro(in glass, or test tubes) tests for total antioxidant capacity emerged. They were based on measuring the destruction of oxidized test compounds by direct reactions with the antioxidants in foods.

Many dietary supplements arrived on the market. They contained purified antioxidants, such as resveratrol and EGCG that were and still are widely assumed by many to be quite healthy at any dose.

Even today, many advertisements for popular ‘superfoods’, beverages and dietary supplements highlight the huge antioxidant activities of their products.

This assumes that dietary antioxidants exert their health effects by reacting directly with RONS and free radicals, destroying them. They were very popular years ago and led to one ‘superfruit’, açaí, being identified as having the highest antioxidant activity of any food.

So, for several years, the U.S. Department of Agriculture (USDA) listed the in vitroantioxidant capacities of many foods and spices.

However, as scientists and physicians learned more about human nutrition, they realized that the caloric restriction that worked for other organisms did not work for humans. This required changing the paradigm from reductionist thinking to systems thinking.

Reductionist thinking assumed that there is a linear relationship between the dose and the physiological effect of potential toxins. It also assumes that if a small amount of an antioxidant that is present in food (like EGCG in green tea) is healthy, then much larger amounts in a dietary supplement would be even healthier – especially if they were ‘natural’.

In contrast, systems thinking does recognize the nonlinear and cyclic nature of life, while accepting the concept of hormesis. That is, hormesis recognizes that moderate levels (or doses) of RONS are needed for good health.