A Nutty Way To Improve
Cholesterol In Diabetes
posted December 09, 2004
Thirty grams of walnuts/day (8-10)
delivering substantial amounts of polyunsaturated fatty acid improved the lipid
profile of patients with type 2 diabetes.
Including Walnuts in a Low Fat/Modified Fat Diet Improves HDL
Cholesterol-to-Total Cholesterol Ratios in Patients With Type 2 Diabetes."
The aim of the study was to examine the effect of a moderate-fat diet inclusive
of walnuts on blood lipid profiles in patients with type 2 diabetes.
National Centre of Excellence for Functional Foods and former Smart Foods Centre
Director Professor Linda Tapsell said the research had demonstrated how a diet
including 8-10 walnuts a day delivered the right kinds of fats and fatty acids
that might help the body address one of the problems associated with early stage
Type 2 Diabetes - insulin resistance - which hinders the absorption of glucose
from the bloodstream into human cells.
"We understood the relationship between insulin resistance and fatty acids, and
when we looked at the composition of walnuts we thought that they could be
useful in delivering the right kinds of fatty acids. We knew walnuts contained
substantial amounts of these fats, so our challenge was to prove that the
theoretical benefits were real," Professor Tapsell said.
The team of dietitians from the Smart Foods Centre and the Illawarra Diabetes
Service developed individualised diets for around 60 people with Type 2 Diabetes
for the six-month study. The diets were based on the core food groups of cereals
and breads, fruit and vegetables, lean meat, fish, low-fat dairy products, oils,
avocadoes, peanut butter and nuts. Each diet in the treatment group included 30g
of walnuts (equivalent to around 8-10 nuts) per day.
The diets were carefully modeled to balance all the other dietary factors such
as carbohydrates, proteins, calories and fats from the other foods to ensure the
benefit was correctly attributed to the walnuts.
"The walnuts took the guesswork out of getting the right fats into the diet. We
knew walnuts would deliver," Professor Tapsell said. "Thus, people with type 2
diabetes could ask their doctor or dietitian about the benefits of including
walnuts in their dietary management."
Professor Tapsell said the study had been important because it confirmed the
theoretical benefits of a certain food. "Food companies need this kind of
research because it assists them in making legitimate claims about the benefits
of certain foods. This particular research finding is also useful for doctors
and dietitians when they provide advice to people on how to get good fatty acids
into their diets," she said.
It was a parallel randomized controlled trial comparing three dietary advice
groups each with 30% energy as fat: low fat, modified low fat, and modified low
fat inclusive of 30 g of walnuts per day. Fifty-eight men and women, mean age
59.3 +/- 8.1 years, started the trial. Dietary advice was given at baseline with
monthly follow-up and fortnightly phone calls for support. Body weight, percent
body fat, blood lipids, HbA(1c), total antioxidant capacity, and erythrocyte
fatty acid levels were measured at 0, 3, and 6 months.
The results showed that the walnut group achieved a significantly greater
increase in HDL cholesterol-to-total cholesterol ratio (P = 0.049) and HDL (P =
0.046) than the two other treatment groups. A 10% reduction in LDL cholesterol
was also achieved in the walnut group, reflecting a significant effect by group
(P = 0.032) and time (P = 0.036). There were no significant differences between
groups for changes in body weight, percent body fat, total antioxidant capacity,
or HbA(1c) levels. The higher dietary polyunsaturated fat-to-saturated fat ratio
and intakes of omega-3 fatty acids in the walnut group were confirmed by
erythrocyte biomarkers of dietary intake.
From the results it was concluded that structured "whole of diet" advice that
included 30 g of walnuts/day delivering substantial amounts of polyunsaturated
fatty acid improved the lipid profile of patients with type 2 diabetes.