David sent this new study:
Food Groups And Risk Of All-Cause Mortality: A Systematic Review And Meta-Analysis Of Prospective Studies, American Journal of Clinical Nutrition, Online 26 April 2017
Objective: The aim of this meta-analysis was to synthesize the knowledge about the relation between intake of 12 major food groups, including whole grains, refined grains, vegetables, fruits, nuts, legumes, eggs, dairy, fish, red meat, processed meat, and sugar-sweetened beverages, with risk of all-cause mortality.
Results: With increasing intake (for each daily serving) of whole grains (RR: 0.92; 95% CI: 0.89, 0.95), vegetables (RR: 0.96; 95% CI: 0.95, 0.98), fruits (RR: 0.94; 95% CI: 0.92, 0.97), nuts (RR: 0.76; 95% CI: 0.69, 0.84), and fish (RR: 0.93; 95% CI: 0.88, 0.98), the risk of all-cause mortality decreased; higher intake of red meat (RR: 1.10; 95% CI: 1.04, 1.18) and processed meat (RR: 1.23; 95% CI: 1.12, 1.36) was associated with an increased risk of all-cause mortality in a linear dose-response meta-analysis. A clear indication of nonlinearity was seen for the relations between vegetables, fruits, nuts, and dairy and all-cause mortality.
Optimal consumption of risk-decreasing foods results in a 56% reduction of all-cause mortality, whereas consumption of risk-increasing foods is associated with a 2-fold increased risk of all-cause mortality.
In conclusion, an optimal intake of whole grains, vegetables, fruits, nuts, legumes, and fish, as well as reduced consumption of red and processed meats and SSBs [sugar-sweetened beverages], can lead to an important decrease—by about 80%—in the relative risk of premature death when compared with intakes always from the highest risk category.
It reinforces the message that eating red or processed meat leads to an earlier death.
But I’ve grown wary of meta-analyses. They are only as good as the studies they include. This one included the PREDIMED study (the famous Mediterranean Diet study), which was awful. I wrote about it here:
So, for example, this new meta-analysis found that eating nuts was beneficial. Authors of the PREDIMED study report the following conflicts of interest: California Walnut Commission, International Nut and Dried Fruit Council. That gets buried in a meta-analysis.
While I’m talking about the Mediterranean diet … Everyone keeps saying how great it is. I don’t think it’s so great. PREDIMED, a big, famous, randomized control trial of the Mediterranean diet found:
The Mediterranean diet groups did not reduce risk for heart attack, death from cardiovascular causes, or death from any cause. “Only the comparisons of stroke risk reached statistical significance.”
The Mediterranean diet is full of processed oils, dairy fats, and animal foods. It shows benefit in spite of those ingredients because it also includes more vegetables than an American diet. Or, it did.