Diet and lifestyle changes are
very important interventions to prevent and control type 2 diabetes.
Beans are high in protein,
omega-3 fatty acids and anti-oxidants, and low in fat. They are also good
sources of iron, folate, magnesium and zinc. Earlier studies found that beans
have some action similar to the diabetes medication, acarbose.
It is also known that beans have
a low glycemic index (GI) which means they produce a relatively low rise in
blood glucose after a meal. However, white rice has a high GI and can cause
postprandial glycemic elevations, which damage the tissues and other organs.
So, to find out if the
postprandial glucose values are lowered by beans and rice combo diet, American
researchers, Sharon Thompson, Donna Winham, and Andrea Hutchins, compared the
glycemic response of beans and rice meals with rice alone in adult type 2
Data from seventeen men and women, with type 2 diabetes
controlled on metformin or diet / exercise, between the ages of 35 and 70 years
was analysed in this study. The researchers selected pinto beans (Glycemic
Index = 45), black beans (GI = 20) and red kidney beans (GI = 20) and long grain
white rice (GI = 80) for their study. Participants received the four test meals
in random order. Three meals included pinto beans, black beans or dark red
kidney beans along with half a cup of white long grain rice respectively. The
amount of beans was standardized to provide 50g of carbohydrates while the
weight of the white rice was kept constant. The fourth meal was the control
meal which included 180g of steamed long grain white rice. Meals were consumed
at breakfast after a 12-hour fast.
Capillary blood glucose concentrations at baseline and at
30 minute intervals up to 180 minutes following the meal were collected. The
results of the study were analyzed statistically.
The results showed
that postprandial glucose concentrations were significantly lower for all three
traditional bean and rice meals as compared with the white rice meal.
The findings are in agreement
with other studies that show intermediate responses with mixed meals of high
and low GI foods.
The results also show that -
All three test meals reduced the average 2-hour
postprandial glucose below 140 mg/dl, the International Diabetes Federation
recommended glycemic control goal.
Counseling patients to exclude cultural foods like the
bean and rice combination may be unwarranted for persons with type 2 diabetes,
especially in the U.S., Latin America, and Mediterranean and Middle East
The three different beans varieties exhibited
significantly different levels of glycemic response. The pinto and black bean
and rice combinations produced a lower glycemic response overall than the dark
red kidney bean and rice meal.
The authors suggested that it is important to investigate
multiple bean varieties rather than assuming all are the same.
'Dietary recommendations, materials
and counseling should be culturally sensitive and take into account valued
traditional foods such as beans, especially when the scientific evidence
supports their beneficial role in the diet', concluded the researchers.
They further add - 'While promoting
traditional foods is a non-pharmacological way to manage type 2 diabetes,
knowing which beans are most effective can help improve dietary adherence with
an appropriate cultural twist'.
Source: Thompson SV, Winham DM, Hutchins AM. Bean and rice
meals reduce postprandial glycemic response in adults with type 2 diabetes: a
cross-over study. Nutr J. 2012 Apr 11;11(1):23.