“You better avoid pasta and bread”, is a common advice from diet gurus. However, a recent study shows that eating protein from plant-based foods such as pasta and bread is not so bad for you after all. It would in fact reduce your risk of premature death. So it’s better not to scrape whole grain products out of your diet. But is that really true?
Where did this news come from?
American researchers have discovered a link between deaths and the presence of animal and plant proteins in a person’s diet. Animal proteins are mainly found in meat, milk and milk products. Vegetable proteins are in grains, legumes, nuts and vegetables.
For their study, the researchers followed more than 400,000 people over 16 years. At the start of the study, the researchers collected the dietary habits of the participants via questionnaires. During the follow-up, they tracked deaths from cancer and cardiovascular disease.
The researchers found that a diet rich in plant-based proteins was combined with a 5% decrease in deaths. Replacing eggs with plant proteins led to a 21% drop in deaths in women and 24% in men. Replacing red meat reduced mortality by 15% and 13% respectively.
The researchers conclude that a diet rich in plant proteins can thus reduce mortality.
How should we interpret these results?
This study is a cohort study. This is a type of acting investigation that can establish links but cannot prove a cause-and-effect relationship. For example, there are indeed fewer deaths among participants who ate more plant proteins, but this may also be due to other factors.
Participants who ate a lot of plant proteins were less likely to be overweight or obese, were more physically active, drank less alcohol and smoked less. The latter was particularly noteworthy: in the men, only 6% of the group smoked with a diet rich in plant-based proteins, compared with 20% in the group with a diet rich in animal protein. Among women, this was 9% and 23% respectively.
A serious limitation of the study is that during the whole 16 years of the study, the researchers only questioned the dietary habits of the participants once, at the start of the study. They hypothesize that the participants followed roughly the same diet for 16 years, which is unlikely.
A final problem is that the higher mortality in the group with a diet rich in animal protein could be due to the fact that these proteins occur together with saturated fatty acids (namely in meat). They do increase the risk of cardiovascular disease. So it is the saturated fatty acids in meat that can be harmful, not the animal protein.
US researchers find that people who eat a lot of plant protein live longer than those who eat a lot of animal protein. But the participants in this study who ate a lot of animal protein also smoked more often, drank more alcohol and were less active. Of course, these factors can explain all or part of the results. So, it’s hard to tell if plant eaters really do live longer.