A smart new study in the journal BMJ Open Diabetes Research & Care, starts to really tease apart the connections between walnuts, diet and heart health. Previous research has certainly found links between nuts and cardiovascular health, and it makes good sense: the omega fatty acids in walnuts, among their many other nutrients, are thought to explain the link. But the new study finds something slightly different. Although people who added walnuts to their diets reaped a number of heart benefits, so did people who were asked to exclude walnuts from their diets. The only thing that improved in the walnut group was how healthy people ate otherwise – which suggests that adding a single healthy food to one’s diet may work at least as much psychologically as physiologically.
So here’s what happened in the study. The team, led by David L. Katz, founding director of the Yale University Prevention Research Center, had 112 participants add about 2 ounces of walnuts to their daily diets for six months. Then, after a break, the participants purposely omitted walnuts from their diets for another six months. Additionally, half of each group were counseled about healthy nutrition, namely about offsetting the addition of the walnuts by cutting calories. Half did not receive nutrition counseling.