People who want to live as long as possible should eat about a pound a day of fruit and vegetables. Chinese and American nutritionists draw this conclusion in an article published in the British Medical Journal. The researchers gathered data from 16 big epidemiological studies and re-analysed them. They had data on 833234 people.
Fruit and vegetables
The researchers performed statistical analysis to check for publication bias, and found none. This means that it was not just studies that show that fruit and vegetables are healthy that were published in scientific journals and that studies with different conclusions had been rejected.
Some studies express fruit and vegetable intake in servings; others use grams. For both vegetables and fruit 1 serving is about 80 grams.
The researchers discovered that for every 80 g serving of fruit or vegetables that you eat per day your chance of having fatal cardiovascular problems decreases by 5 percent. And every serving eaten per day reduces the chance of developing a fatal form of cancer by 3 percent.
Optimal health protection was obtained by eating 5-6 servings amounting to about half a kilogram per day. Higher intake does not lead to a further reduction in mortality risk.
The protective effect of vegetables on cancer was not statistically significant in this study. “It is possible, however, that fruit and vegetable consumption might have stronger effects on specific cancer sites”, the researchers write. “In addition, different types of fruit and vegetables might have different effects on cancer risk. Future studies are needed to be more specific about types of cancer and the role of different groups of fruit and vegetables.”
Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies.
To examine and quantify the potential dose-response relation between fruit and vegetable consumption and risk of all cause, cardiovascular, and cancer mortality.
Medline, Embase, and the Cochrane library searched up to 30 August 2013 without language restrictions. Reference lists of retrieved articles.
Prospective cohort studies that reported risk estimates for all cause, cardiovascular, and cancer mortality by levels of fruit and vegetable consumption.
Random effects models were used to calculate pooled hazard ratios and 95% confidence intervals and to incorporate variation between studies. The linear and non-linear dose-response relations were evaluated with data from categories of fruit and vegetable consumption in each study.
Sixteen prospective cohort studies were eligible in this meta-analysis. During follow-up periods ranging from 4.6 to 26 years there were 56,423 deaths (11,512 from cardiovascular disease and 16,817 from cancer) among 833,234 participants. Higher consumption of fruit and vegetables was significantly associated with a lower risk of all cause mortality. Pooled hazard ratios of all cause mortality were 0.95 (95% confidence interval 0.92 to 0.98) for an increment of one serving a day of fruit and vegetables (P=0.001), 0.94 (0.90 to 0.98) for fruit (P=0.002), and 0.95 (0.92 to 0.99) for vegetables (P=0.006). There was a threshold around five servings of fruit and vegetables a day, after which the risk of all cause mortality did not reduce further. A significant inverse association was observed for cardiovascular mortality (hazard ratio for each additional serving a day of fruit and vegetables 0.96, 95% confidence interval 0.92 to 0.99), while higher consumption of fruit and vegetables was not appreciably associated with risk of cancer mortality.
This meta-analysis provides further evidence that a higher consumption of fruit and vegetables is associated with a lower risk of all cause mortality, particularly cardiovascular mortality.
PMID: 25073782 [PubMed – indexed for MEDLINE] PMCID: PMC4115152