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More Fruit and Vegetables No Better for Breast Cancer Survival
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John P. Pierce, PhD; Loki Natarajan, PhD; Bette J. Caan, et al. Influence of a Diet Very High in Vegetables, Fruit, and Fiber and Low in Fat on Prognosis Following Treatment for Breast Cancer .
The Women's Healthy Eating and Living (WHEL) Randomized Trial. JAMA. 2007;298:289-298. Context Evidence is lacking that a dietary pattern high in vegetables, fruit, and fiber and low in total fat can influence breast cancer recurrence or survival. Objective To assess whether a major increase in vegetable, fruit, and fiber intake and a decrease in dietary fat intake reduces the risk of recurrent and new primary breast cancer and all-cause mortality among women with previously treated early stage breast cancer. Design, Setting, and Participants Multi-institutional randomized controlled trial of dietary change in 3088 women previously treated for early stage breast cancer who were 18 to 70 years old at diagnosis. Women were enrolled between 1995 and 2000 and followed up through June 1, 2006. Intervention The intervention group (n = 1537) was randomly assigned to receive a telephone counseling program supplemented with cooking classes and newsletters that promoted daily targets of 5 vegetable servings plus 16 oz of vegetable juice; 3 fruit servings; 30 g of fiber; and 15% to 20% of energy intake from fat. The comparison group (n = 1551) was provided with print materials describing the "5-A-Day" dietary guidelines. Main Outcome Measures Invasive breast cancer event (recurrence or new primary) or death from any cause. Results From comparable dietary patterns at baseline, a conservative imputation analysis showed that the intervention group achieved and maintained the following statistically significant differences vs the comparison group through 4 years: servings of vegetables, +65%; fruit, +25%; fiber, +30%, and energy intake from fat, ?13%. Plasma carotenoid concentrations validated changes in fruit and vegetable intake. Throughout the study, women in both groups received similar clinical care. Over the mean 7.3-year follow-up, 256 women in the intervention group (16.7%) vs 262 in the comparison group (16.9%) experienced an invasive breast cancer event (adjusted hazard ratio, 0.96; 95% confidence interval, 0.80-1.14; P = .63), and 155 intervention group women (10.1%) vs 160 comparison group women (10.3%) died (adjusted hazard ratio, 0.91; 95% confidence interval, 0.72-1.15; P = .43). No significant interactions were observed between diet group and baseline demographics, characteristics of the original tumor, baseline dietary pattern, or breast cancer treatment. Conclusion Among survivors of early stage breast cancer, adoption of a diet that was very high in vegetables, fruit, and fiber and low in fat did not reduce additional breast cancer events or mortality during a 7.3-year follow-up period. |
COMMENT: This study showed that breast cancer survivors who ate substantially more than the recommended five servings a day did not have lower risk of recurrence or new primary breast cancer or lower risk of overall mortality) than those who ate only the recommended amount.
The high fruit and vegetable diet also showed no benefit among women who, you might expect, stood to gain the most – those with a baseline diet which was low in fruits and vegetables or high in fat.
These negative findings from the Women's Healthy Eating and Living (WHEL) are inline with other studies, such as a very large study published in 2001 which also found no benefit in breast cancer from eating ?5 portions'. In this study, 20 named researchers investigated 7,377 incident invasive breast cancer cases and a wide variety of fruit and vegetable intakes among 351,825 women at 17 cancer research centres in the USA, Germany, Netherlands, and Sweden. They found no association for green leafy vegetables, 8 botanical groups, and 17 specific fruits and vegetables. They concluded:
'These results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk'.[1]
Strangely, one of the researchers, Dr Marcia Stefanick reportedly "urged people not to interpret them as evidence that eating fruit did not make a difference in breast cancer."
On this point, Dr Malcolm Kendrick writes:
"It is an interesting phenomenon. Researchers urging everyone to ignore the results of their research.
I first came across it after the MRC trial on hypertension that showed absolutely no effect on death from CHD. The researchers immediately stated, if memory serves, this does not mean that lowering blood pressure does not protect against CHD."
Another study of over 100,000 people was published in 2004. This study, conducted by the Harvard School of Public Health, showed that, 'Increased fruit and vegetable consumption was associated with a modest although not statistically significant reduction in the development of major chronic disease' [emphasis added]. They continued: 'The benefits appeared to be primarily for cardiovascular disease and not for cancer.'[i] And concluded:
'Consumption of five or more servings of fruits and vegetables has been recommended . . . but the protective effect of fruit and vegetable intake may have been overstated.'
Whenever studies such as these are reported, the diet police repeat their dogma that eating the recommended number of fruit and vegetables has numerous health benefits; they say that the evidence is 'overwhelming'. But they never seem able to quote any of that evidence or to specify exactly what the benefits are. In view of the above studies, that will probably come as no real surprise. The point is that, just like almost all the health advice we have had forced down our throats and come to believe over the last few decades, there is practically no basis for '5 portions' advice in science.
Unfortunately, this is an area where nearly everyone is still in massive denial over the influence of sugars on cancer. Even though a Nobel Prize was awarded to the German physician, Dr Otto Warburg, in 1931 for recognising this, three-quarters of a century later very few physicians have applied this basic concept.
Dr Barnett Kramer, of the National Institutes of Health in the US, said of the healthy eating message:
'A lot of the public is completely unaware that the strength of the message is not matched by the strength of the evidence.'
That we are still kept unaware of it demonstrates just how strong an influence the diet dictocrats have on our minds and the news media.
References
1. Smith-Warner SA, et al. Intake of Fruits and Vegetables and Risk of Breast Cancer: A Pooled Analysis of Cohort Studies. JAMA 2001; 285: 769-776.
2. Hung H-C, Joshipura KJ, Jiang R, et al. Fruit and Vegetable Intake and Risk of Major Chronic Disease. J Nat Canc Inst 2004; 96: 1577-1584.
Last updated 19 July 2007
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