Not too long ago I wrote a post compiling the latest studies and reviewing the intake of vegetables and fruits and health, especially aimed at trying to know the evidence about the ideal amount of this food group. From the data it could be deduced that there was clear and important evidence of an increasing positive relationship for an intake of up to three servings per day. From that amount and up to five daily servings, the favorable relationship continued to exist, but it was less clear and its growth was also much less pronounced. And at the time I couldn’t find any solid evidence that eating more than 5 servings of vegetables and fruits a day was especially beneficial.
However, since some sources It is often insisted that dietary recommendations in this regard should suggest «at least» five servings of vegetables and fruits. Something I don’t agree with too much, considering the results I summarized in that post and which showed that there is no solid data to make health claims beyond five daily servings. Furthermore, as also explained in that post, I also did not find evidence to prioritize fruits over vegetables, something that is also usually done in some guidelines.
To complete all this information, just a few days ago a new meta-analysis on the subject was published, analyzing the relationship between the amount of vegetables and fruits in the diet and various types of mortality. «It’s about the investigation»Fruit and Vegetable Consumption and Mortality: Results from Two Prospective Cohort Studies of American Men and Women and a Meta-Analysis of 26 Cohort Studies» (2021), a work published in the journal of the American Heart Association and that is especially relevant because it is based on a huge amount of data (26 observational studies that followed almost two million people for several decades) and because it carries the signature of some of the first experts in the area of nutrition at the Harvard School of Public Health.
First of all, it is worth clarifying that in this study a serving refers to an amount of 80 grams of food, much less than the 140-150 grams per serving that are usually considered in Spain.
Well, let’s see the results, first visually. The following figure shows the dose response based on the calculated curves, which shows the relationship between the amount ingested and various types of mortality (click to enlarge):
The first row of graphs shows the results on total vegetable and fruit intake, the second row on fruit intake, and the third row on vegetable intake. In each of them, a simple view can show quite well the approximate values at which the curves reach their minimum values. But in any case, in the summary table of the original document the authors explain it clearly:
«A higher intake of fruits and vegetables is used with lower overall and cause-specific mortality (…). The lowest risk of mortality is detected for approximately 5 daily servings, but above that amount the risk is not reduced more… The mortality risk reduction thresholds were 2 daily servings for fruit intake and 3 daily servings for vegetable intake.»
And they also detail it in the summary:
«Higher intakes of most fruit and vegetable subgroups were associated with lower mortality, with the exception of starchy vegetables such as peas and corn. Intake of fruit and potato juices is not associated with overall mortality.» and for specific reasons. (…) the risk reduction stabilized at about 5 servings of fruits and vegetables per day. These findings support current dietary recommendations to increase intake of fruits and vegetables, but not fruit juices and potatoes.
That is to say, the lowest mortality values were reached with about five daily servings of vegetables and fruits, distributed as 2 of fruit and 3 of vegetables, without significant improvements being detected at higher quantities. Five portions of 80 grams, which would be equivalent to 400 grams in total or about three «Spanish» portions. Furthermore, vegetables achieve lower mortality values at larger quantities than fruits, so it seems that vegetables should be prioritized over fruits.
In short, I believe that the conclusions of this study continue to largely confirm the conclusions of the post I wrote: there is solid evidence to recommend a minimum of 3 «Spanish portions» (140 grams each) daily, some evidence to suggest going up to 5, but we don’t know what happens beyond. Other recent large reviews, analyzing other relevant health indicators, reach similar results and show the same «benefit ceiling» between 3-5 servings (1, 2, 3, 4).
Some data that must be taken into account when formalizing diets, I believe.
