In 1956, Denham Harman proposed the free-radical theory of aging and even demonstrated that free radical reactions contribute to the degradation of biological systems.

Molecules that contain heavier isotopes are less prone to destructive effect of free radicals (which is the key point of the free-radical theory of ageing).

These are examples of how the free-radical theory of aging has been used to neatly "explain" the origin of many chronic diseases.

The radish flavor comes from a phytochemical that may act as protection against vectors (see also radical or free-radical theory) while the broccoli plant is still young.

"The free-radical theory is a really big theory of aging nowadays," Dr. Rollo said.

"It was a nice test of the free-radical theory," Dr. Rollo said.

It is believed that NDGA reduces cell damage by free radicals, so under the free-radical theory of aging, could be responsible for the bush's long life.

The free-radical theory of aging proposes that free radicals underlie the aging process itself.

Denham Harman's free-radical theory of aging later provided a plausible causal mechanism for Pearl's hypothesis.

One thing is sure: The free-radical theory of aging is complicated.