Evidence continues to mount supporting the role of almonds and other tree nuts as part of an overall dietary pattern that is beneficial for those with type 2 diabetes. Three new studies suggest a relationship between regular consumption of tree nuts, such as almonds, and improvement in various markers of health in type 2 diabetes.
A randomized controlled clinical study investigated the effects of adding 1.5 ounces of almonds to the diet for 12 weeks on diabetes and heart disease risk factors in 21 adults with poorly controlled type 2 diabetes. Participants in the almond-consuming group (n=10; mean age 57.8 years) experienced nearly a 30% reduction in C-reactive protein (CRP) levels, a marker of inflammation associated with increased heart disease risk, compared to those who did not consume almonds (n=11; mean age 54.7 years). Participants also experienced no change in body mass after 12 weeks of almond consumption.
"These findings suggest that adding almonds to the diet can be an effective, simple strategy to help reduce inflammation in people with poorly controlled diabetes," said Karen Sweazea, PhD, Assistant Professor at Arizona State University and lead researcher of the study. Inflammation is thought to play a role in heart disease, diabetes, and other chronic diseases, and elevated CRP is linked with an increased risk of cardiovascular disease in people with type 2 diabetes.
There were no differences observed after 12 weeks between groups in blood pressure, lipids, fasting body glucose or other measures of glycemic control, or in biomarkers of oxidative stress or other markers of inflammation, and the study was limited by small sample size and reliance on self-reported, incomplete dietary records.
This comes on the heels of two related meta-analyses from the University of Toronto, which demonstrated that eating tree nuts was associated with positive effects on glycemic control in adults with type 2 diabetes or metabolic syndrome, a collection of risk factors associated with increased cardiovascular disease risk. One study, the first systematic review of the effects of tree nuts on metabolic syndrome criteria to be conducted, included 47 randomized controlled trials with more than 2,200 participants and found that eating about two ounces (50 g) of tree nuts per day for an average of eight weeks was associated with significant reductions in triglycerides and fasting blood glucose. No adverse effects were seen on waist circumference, HDL-cholesterol, or blood pressure, suggesting an overall metabolic benefit on tree nuts. The study was limited by the fact that most of the trials were of short duration (< 12 weeks) and considered to be of low quality as assessed by methodological quality score, and that substantial inter-study heterogeneity remained unexplained.
A second meta-analysis examined the effect of tree nut consumption on glycemic control in those with diabetes. The analysis included 12 randomized clinical trials with 450 adult participants and found that diets containing tree nuts at an average dose of about two ounces (56 g) per day for an average of eight weeks significantly lowered fasting blood glucose and HbA1c (a measure of long-term glucose control) compared with diets without tree nuts. No significant effects were observed for fasting insulin or insulin resistance; however, the direction of effect favored tree nuts. The study was limited by the fact that the majority of trials were of short duration and of poor quality with a methodological quality score <8.0.
Researchers suggest that the unique nutrient profile of nuts may be a contributing factor driving improved glycemic control in these studies, in particular their magnesium and monounsaturated fat (MUFA) content.
Among tree nuts, almonds contain a particularly high proportion of MUFAs, providing 9 grams per 1 ounce serving (about 50% of their total calories), and are among the highest dietary sources of magnesium, providing 20% of the DV per serving.
Overall, the nutrient profile of almonds – low on the glycemic index and providing a powerful nutrient package including hunger-fighting protein (6 g/oz), filling dietary fiber (4 g/oz), "good" fats and important vitamins and minerals such as vitamin E (7.3 mg/oz), magnesium (77 mg/oz) and potassium (200 mg/oz), combined with their versatility and many forms, makes them a smart snack for those with impaired glucose tolerance or type 2 diabetes.