Most studies use questionnaires to quiz study participants about what they ate and when, which leaves most nutritional studies subject to the vagaries of human recall.
But a group of European researchers used an objective measurement — a composite score of blood biomarkers of vitamin C and carotenoids (the richly colored pigments of yellow, red and green on fruits and vegetables) — to measure the amount of fruits and veggies eaten.
The study compared nearly 10,000 adults with new-onset type 2 diabetes to a group of nearly 14,000 adults who remained free of diabetes. All were participating in the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct study that took place in eight European countries.
There was a 25% lower risk of developing type 2 diabetes for every 66 extra grams of fruit and vegetables eaten each day, the study found.
That’s not much — just over 1/3 cup of either fruits or veggies.
“The public health implication of this observation is that the consumption of even a moderately increased amount of fruit and vegetables among populations who typically consume low levels could help to prevent type 2 diabetes,” the study said.
“It should be noted that these findings and other available evidence suggest that fruit and vegetable intake, rather than vitamin supplements, is potentially beneficial for the prevention of type 2 diabetes.”
Whole grains good, except popcorn
Foods and ingredients considered whole grains were: whole wheat and whole wheat flour, whole oats and whole oat flour, whole cornmeal and whole corn flour, whole rye and whole rye flour, whole barley, bulgur, buckwheat, brown rice and brown rice flour, popcorn, amaranth and psyllium.
Results showed that eating two or more servings a week of oatmeal was associated with a 21% lower risk of diabetes, a 15% lower risk for added bran and a 12% lower risk for brown rice and wheat germ, when compared to eating less than one serving a month.
There was a 19% lower risk of diabetes with eating one or more servings a day of whole grain cold breakfast cereal and a 21% lower risk for the same amount of dark bread, again compared to eating less than one serving a month.
These statistics held true even after adjusting for body mass index and other lifestyle and dietary risk factors for diabetes, the study said.
On average, people who ate the most whole grains — around four to six servings a week — had a 29% lower rate of type 2 diabetes than those who ate none or less than one serving a month.
On a daily basis, reductions in risk plateaued at about two servings a day for total whole grain intake, and a half a serving a day for whole grain cold breakfast cereal and dark bread.
One grain, however, had a negative effect: popcorn. The study found an increased rate of type 2 diabetes with eating one or more servings of popcorn a day. The effect occurred only when a full serving of 1 cup or more was eaten.
While popcorn, as a whole grain, has relatively high amounts of fiber and fills us up, the researchers pointed out that Americans often eat their popcorn with lots of salt and butter, and sometimes sugar or cheese, which can lessen its healthy properties. In addition, most Americans don’t pop from a whole grain but purchase “ultraprocessed” versions that are microwaved, home popped, or ready to eat.