The Link Between Fruit, Vegetables and Health - CHD

References 1 and 2 present the results of two large studies relating fruit and vegetable consumption to Coronary Heart Disease. In the first, 84,251 women aged 34-59 at the start of the satudy were followed for 14 years, and 42,148 men aged 40-75, were followed for 8 years. There were a total of 1,127 cases of CHD among the women, and 1,063 cases of CHD among the men. In the second study, 9,608 adults, aged 25-74 at the start were followed for 19 years. There were a total of 1,786 CHD events in this group.

Analysis of these data show that the relative risk (RR) is indeed lower when more fruits and vegetables are consumed. The first reference finds that the highest quintile (a division or grouping of one-fifth of a population ordered by the quantity of vegetables consumed) of fruit and vegetable consumers has a reduced CHD risk by a factor of 0.80 (with a Margin of Error of 0.69 to 0.93) compared to the lowest quintile. Participants in the highest quintile ate approximately 9-10 servings a day, whereas those in the lowest quintile ate 2-3 servings a day. (A serving, in this study, was defined as a "natural" portion - e.g., one banana, one small glass of tomato juice, or a volume or weight commonly used in a U.S. meal).

The second reference finds that people eating fruit and vegetables more than 3 times a day have an RR of 0.75 (Margin of Error - 0.56 to 1.03), compared to people who eat fruit and vegtables less than once a day. Those who ate three times a day, ate on average more than double the weight of fruits and vegetables that those who ate less than once a day - 520 grams compared to 242 grams (19 vs. 9 oz), or 5 vs. 2.5 servings.

A crude combination of these two results (this is like comparing oranges and grapefruit - one study uses quintiles, and the other - times per day) - gives an RR of 0.79 (0.68 - 0.90 Margin of Error). Statistically, one concludes that large servings of fruit and vegetables have beneficial effects that play a role in CHD prevention. However, it is not a panacea that would eliminate, or provide a dramatic reduction in CHD. A 21% reduction in CHD is comparable to results obtained with some statins, but without the potential for serious side effects.

In addition, the first reference provides some indication of those vegetables and fruits that may be more effective than others.

• Vegetables and fruits have approximately equal effect.

• Citrus juice has much less effect than the citrus fruit.

• Cruciferous vegetables may be slightly less effective than green leafy vegetables.

• Legumes and potatos seem not to have any beneficial effect.

We should emphasize again that given the limited statistical sample, and possibilities of hidden errors in these types of systematic studies, this list should be considered tentative at best.