A study that was first published in September 2108 has been getting recent media attention for its claims about the potential negative effects of low-carbohydrate diets on mortality.
One headline this week proclaims the study, “Has Bad News For The Keto Diet.”
We dug deeper into this study to determine if it really was “bad news” for the ketogenic diet.
How the Study Was Done
A group of researchers from Brigham and Women’s Hospital in Boston studied approximately 15,000 adults who completed a dietary questionnaire when they enrolled in an Atherosclerosis Risk in Communities (ARIC) study 25 years ago.
They compared that data to information regarding carbohydrate intake gleaned from seven other studies in a meta-analysis which included approximately 432,000 individuals.
The researchers were looking for a link in self-reported carbohydrate consumption and all-cause mortality in the ARIC-enrolled group.
What the Study Found
After analyzing death rates within both groups and performing statistical analysis, the researchers found, “Both high and low percentages of carbohydrate diets were associated with increased mortality.”
Their findings indicated that the lowest mortality rate was found in the group that reported obtaining 50% to 55% of their calories from carbohydrates and that the groups that reported either high or low carbohydrate consumption had higher mortality.
Interestingly however, they noted that carbohydrate consumption was not the only variable that seemed to influence mortality. How the low-carbohydrate group replaced the calories they would have been getting from carbohydrates made a difference.
To that point, they said, “Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain breads, were associated with lower mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and mortality.”
While the goal of the researchers was to find an association between carbohydrate consumption and mortality, their findings about protein and fat sources are very interesting.
When their study subjects followed a low-carbohydrate diet and made up those “missing” calories with meat-based protein and fat sources, they showed higher mortality.
However, for subjects that followed a low-carb diet, but used plant-based protein and fat sources, they had lower mortality.
These results may indicate as much about the possible dangers of excess processed meat consumption, and the need for a varied diet including vegetables, nuts and seeds, as it does about carbohydrate consumption.
You can read the complete study here.