Nutrient Loss 233
in the lowest quartile or quintile consumed less than one serving daily (< 0.8 and
< 0.7). This suggests that small but consistent changes in the type of vegetable
consumption can make important changes in health outcomes.
Consumption of tomatoes and tomato products has also been linked to decreased
risk of prostate cancer. A study by Giovannucci et al. (1995) showed that men in
the highest quintile for consumption of tomato products (10 or more servings per
week) had about a 35% decrease in risk of prostate cancer compared to counterparts
whose consumption put them in the lowest quintile (1.5 or fewer servings of tomato
products per week). It was also shown in a study involving 5,500 Italian people that
eating tomatoes, which are rich in lycopene, was more effective in preventing
digestive tract cancers than eating green vegetables. Individuals who ate tomatoes
at least seven times a week had half the risk of developing these cancers compared
to those who ate tomatoes only once a week. For a similar study involving the
consumption of lutein-rich vegetables, spinach or collard greens, people in the
highest quintile for consumption of these vegetables had a 46% reduction in the risk
of age-related macular degeneration compared to those in the lowest quintile (con-
sumed these vegetables less than once per month) (Seddon et al., 1994).
Flavonoid consumption has been linked to lower risk of heart disease in some
studies. In a study of elderly Dutch men, those consuming the highest tertile of
flavonoids had a 58% lower risk of heart disease than that of their counterparts who
consumed the lowest tertile of flavonoids (Hertog et al., 1993). Those in the lowest
tertile consumed 19 mg or less of flavonoid per day, whereas those in the highest
tertile consumed approximately 30 mg per day or more. Similarly, Finnish subjects
with the highest quartile of flavonoid intake had a risk of mortality from heart disease
that was about 27% (for women) and 33% (for men) lower than that of subjects in
the lowest quartile (Knekt et al., 1996). In the Iowa Women’s Health Study involving
more than 41,000 women, it was found that a diet consisting of garlic, fruits, and
vegetables reduced the risk of colon cancer by 35% (Steinmetz et al.,1994). A similar
study in the Shandong Province in China showed that people who ate garlic and
onions regularly experienced almost 40% less stomach cancer compared to those
who ate them occasionally (Giovannucci, 1999). However, in other studies the
protective effect of flavonoids could not be confirmed. For example, in a study of
Welsh men, flavonoid intake did not predict a lower rate of ischemic heart disease
and was weakly positively associated with ischemic heart disease mortality (Hertog
et al., 1997). In a separate study involving U.S male health professionals, the data
also did not support a strong link between the intake of flavonoids and protection
from coronary heart disease (Rimm et al., 1996).
In these studies and many others (Terry et al., 2001; Hsing et al., 2002; Riboli
and Norat, 2003), fruits and vegetables consumption has been linked with a lower
risk for chronic diseases including specific cancers and heart disease. However,
media and consumer interest in phytonutrients and functional foods is far ahead of
the established proof that documents the health benefits of these foods or food
components for humans. Phytonutrient research is experiencing remarkable growth.
It is hoped that more scientific information on phytonutrient consumption and human
health will be forthcoming in the near future. For now, it appears that an effective
strategy for reducing the risk of cancer, heart disease, and other chronic diseases is