Greek study links diets higher in antioxidants to lower blood sugar levels
by Craig Weatherby
The large ATTICA study in Greece has produced a number of important findings over the years.
For example, see “Fish Inhibits Heart-Attacking Inflammation” and “Fish and Olive Oil May Deter Heart Dysfunction.”
Four years ago, researchers from the University of Athens linked closer adherence to the ideal Mediterranean diet to lower blood sugar levels in ATTICA study volunteers (Panagiotakos DB et al. 2007).
(The ideal Mediterranean diet is low in processed fare but high in fish, olive oil, fruits, nuts, whole grains, and green vegetables.)
Now, a new analysis of diet and health data from people participating in the ATTICA study indicates that antioxidant-rich plant foods—a major part of the ideal Mediterranean diet—may help deter diabetes (Psaltopoulou T et al. 2010).
What the study found
The Greek team analyzed diet and health data from a random sample of 551 men and 467 women who’d participated in the ATTICA study.
Their dietary habits were estimated using a questionnaire, with participants reporting their daily or weekly average intake of fruits, vegetables, beans, non-alcoholic beverages, chocolate, honey, jam, nuts, rice, pastas and grains and other foods.
The antioxidant capacity of the volunteers’ diets was estimated by based on the known antioxidant capacities of Mediterranean foods.
The participants were divided into three groups:
People’s average blood sugar levels predict their future risk of developing diabetes—with high levels being riskier—so the participants’ blood sugar levels were compared with their self-reported diets.
- Type II diabetics
- Non-diabetic people
- People with “impaired fasting glucose” (a risk factor for diabetes)
After controlling for age, gender, body mass index, physical activity, smoking habits and calorie intake, the results linked higher antioxidant intake from foods with lower average blood sugar levels in all three groups (healthy, pre-diabetic, and diabetic).
The scientists noted that the association of higher antioxidant intake with reduced diabetes risk was independent of age, gender and physical activity status… except for obese individuals, whose blood sugar levels were unaffected by antioxidant intake.
The study could not prove a cause-and-effect relation between antioxidant-rich foods and reduced blood sugar levels, because other factors associated with antioxidant-rich foods—such as sugar, starch, and fiber content—could also affect people’s blood sugar levels.
The only way to be sure that food-borne antioxidants themselves—rather than fiber and other nutritional factors in high-antioxidant foods—lower blood sugar is to test the blood sugar effects of supplements containing the same kinds of antioxidants found in the foods people in this study reported eating.
Still, as the researchers wrote, “…the data presented support the view that dietary modification towards higher consumption of antioxidants should be implemented in public health strategies, in order to better control glycemic [blood sugar] markers in individuals, and prevent the development of diabetes…” (Psaltopoulou T et al. 2010).
Why would antioxidants help?
The researchers noted two reasons why antioxidant-rich foods might help keep the body's blood sugar control system running well:
Recent studies suggested that oxidative stress—that is, excessive free radical production—appears to promote diabetes.
Pancreatic cells, which produce insulin, are particularly susceptible to free radicals due to their low levels of antioxidant enzymes.
By damaging the mitochondria (energy centers) of pancreatic beta cells, oxidative stress can kill these critical cells, thereby blunting insulin secretion and allowing blood sugar levels to stay chronically high.
The Greek scientists also noted the well-established fact that higher intakes of food-borne antioxidants are linked to lower markers of inflammation.
Whatever the exact reasons, it's pretty clear that the ideal Mediterranean diet is an ally than can help deter diabetes.
- Psaltopoulou T, Panagiotakos DB, Pitsavos C, Chrysochoou C, Detopoulou P, Skoumas J, Stefanadis C. Dietary antioxidant capacity is inversely associated with diabetes biomarkers: The ATTICA study. Nutr Metab Cardiovasc Dis. 2010 Feb 18. [Epub ahead of print]
- Panagiotakos DB, Tzima N, Pitsavos C, Chrysohoou C, Zampelas A, Toussoulis D, Stefanadis C. The association between adherence to the Mediterranean diet and fasting indices of glucose homoeostasis: the ATTICA Study. J Am Coll Nutr. 2007 Feb;26(1):32-8.