The passage makes it quite clear that ----.

It's common knowledge that antioxidants
protect us from dangerous substances called
free radicals that can create damage leading to
many chronic diseases. Yet scientists say there
is more to learn about the health benefits of
antioxidants. Studies demonstrate that
vegetables, fruits and whole grains supply an
abundance of vitamins and natural
photochemical that act as antioxidants. A
greater consumption of these antioxidant-rich
foods has been shown to lead to higher blood
levels of antioxidant power. Studies also show
that when people eat diets high in antioxidants,
their risk of cancer and heart disease
decreases. However, while antioxidant vitamins
and photochemical are responsible for the
health benefits seen, antioxidants from
supplements may not yield the same results. A
higher dose of antioxidants from supplements
could actually be counterproductive by
upsetting the natural balance of antioxidants in
the body.