Former president, George H.W. Bush once said, "I do not like broccoli. And I haven't liked it since I was a little kid and my mother made me eat it. And I'm President of the United States and I'm not going to eat any more broccoli."

Let's hope he is more negotiable regarding other fruits and vegetables. A recently published study of Chinese natives found that the people who ate the most fruit and vegetables were the least likely to die over the next five years. The effect was strongest in people who ate the most cruciferous vegetables.

Cruciferous vegetables are all members of the mustard family. They include broccoli, Brussels sprouts, cabbage and cauliflower.

A dose-response pattern was seen — the more eaten, the lower the death rate. Cruciferous vegetables seemed to provide the most protection.

The study doesn't show that eating more fruit and vegetables caused people to live longer. It only shows that the two are correlated: people who ate more did live longer. There's no guarantee that the two are related. It does suggest that people seeking a longer life might want to up their fruit and vegetable intake, particularly cruciferous vegetables.

The study was undertaken because Asians tend to eat a more plant-based diet than U.S. natives do. It sought to find the effect of an Asian-style diet on mortality by comparing people's dietary pattern with their five-year risk of death.

For both total fruit and vegetable consumption and for cruciferous vegetable consumption specifically, a dose-response pattern was seen — the more eaten, the lower the death rate. Cruciferous vegetables seemed to provide the most protection.

People who ate the most fruit and vegetables had a total mortality rate about 16% lower than people who ate the least. And people who ate the most cruciferous vegetables had a mortality rate about 22% lower people who ate the least.

The drop in death rate appeared to be mainly due to a decrease in cardiovascular deaths. There was no effect seen on deaths due to cancer.

The study was of nearly 135,000 Shanghai adults. Men and women were studied separately, but gave similar results, and the data from both groups were pooled. Fruit and vegetable consumption was estimated at the study's start using validated food frequency questionnaires.

The subjects were divided into five groups based on their total estimated fruit and vegetable consumption (highest, lowest and three intermediate). A similar grouping was made based on their cruciferous vegetable consumption. Men were tracked for just under five years and women for ten years. Deaths were determined from bi-annual home visits and through national statistics.

Cruciferous vegetables are high in vitamins and fiber. They also contain sulforaphane, a sulfur-containing compound that may have anti-cancer, anti-diabetic and anti-inflammatory properties. Since the study doesn't prove a life-lengthening effect from vegetables, it certainly can't attribute that effect to specific compounds in the vegetables. But its overall findings are consistent with most other nutritional studies.

After all, who can remember the last time a study showed that fruits and vegetables are bad for you?

An article detailing the study was published online by the American Journal of Clinical Nutrition on May 18, 2011. The article will also appear in a future print edition of the journal.

The study was a joint venture between the Vanderbilt University School of Medicine and the Shanghai Cancer Institute.