Nuts as a replacement for carbohydrates in the diabetic diet: a reanalysis of a randomised controlled trial

Abstract

Aims/hypothesisIn line with current advice, we assessed the effect of replacing carbohydrate consumption with mixed nut consumption, as a source of unsaturated fat, on cardiovascular risk factors and HbA1c in type 2 diabetes. The data presented here are from a paper that was retracted at the authors’ request (10.2337/dc16-rt02) owing to lack of adjustment for repeated measures in the same individual. Our aim, therefore, was to fix the error and add new complementary data of interest, including information on clotting factors and LDL particle size.MethodsA total of 117 men and postmenopausal women with type 2 diabetes who were taking oral glucose-lowering agents and with HbA1c between 47.5 and 63.9 mmol/mol (6.5–8.0%) were randomised after stratification by sex and baseline HbA1c in a parallel design to one of three diets for 3 months: (1) ‘full-dose nut diet’ (n = 40): a diet with 2.0 MJ (477 kcal) per 8.4 MJ (2000 kcal) energy provided as mixed nuts (75 g/day); (2) ‘full-dose muffin diet’ (n = 39): a diet with 1.97 MJ (471 kcal) per 8.4 MJ (2000 kcal) energy provided as three whole-wheat muffins (188 g/day), with a similar protein content to the nuts, and the same carbohydrate-derived energy content as the monounsaturated fatty acid-derived energy content in the nuts; or (3) ‘half-dose nut diet’ (n = 38): a diet with 1.98 MJ (474 kcal) per 8.4 MJ (2000 kcal) energy provided as half portions of both the nuts and muffins. The primary outcome was change in HbA1c. The study was carried out in a hospital clinical research centre and concluded in 2008. Only the statistician, study physicians and analytical technicians could be blinded to the group assessment.ResultsA total of 108 participants had post-intervention data available for analysis (full-dose nut group, n = 40; full-dose muffin group, n = 35; half-dose nut group, n = 33). Compared with the full-dose muffin diet, the full-dose nut diet provided 9.2% (95% CI 7.1, 11.3) greater total energy intake from monounsaturated fat. The full-dose nut diet (median intake, 75 g/day) also reduced HbA1c compared with the full-dose muffin diet by −2.0 mmol/mol (95% CI −3.8, −0.3 mmol/mol) (−0.19% [95% CI −0.35%, −0.02%]), (p = 0.026). Estimated cholesterol levels in LDL particles with a diameter <255 ångström [LDL-c<255Å]) and apolipoprotein B were also significantly decreased after the full-dose nut diet compared with the full-dose muffin diet. According to the dose response, the full-dose nut diet is predicted to reduce HbA1c (−2.0 mmol/mol [−0.18%]; p = 0.044), cholesterol (−0.25 mmol/l; p = 0.022), LDL-cholesterol (−0.23 mmol/l; p = 0.019), non-HDL-cholesterol (−0.26 mmol/l; p = 0.020), apolipoprotein B (−0.06 g/l, p = 0.013) and LDL-c<255Å (−0.42 mmol/l; p < 0.001). No serious study-related adverse events occurred, but one participant on the half-dose nut diet was hospitalised for atrial fibrillation after shovelling snow.Conclusions/interpretationNut intake as a replacement for carbohydrate consumption improves glycaemic control and lipid risk factors in individuals wit...

Effect of Nut Consumption on Erectile and Sexual Function in Healthy Males: A Secondary Outcome Analysis of the FERTINUTS Randomized Controlled Trial

“…For that reason, several antioxidants (e.g., polyphenols) and vitamins, that are present in nuts, have been suggested to be effective treatments for ED and at the same time are beneficial for the cardiovascular system [38]. Previous studies reported that chronic consumption of nuts has proven effective for lowering LDL cholesterol [32] and improving glucose metabolism [39], among other cardiovascular risk factors, decreasing the incidence of major cardiovascular events [17]. Therefore, we strongly believe in the necessity to develop similar trials with participants at high cardiovascular risk and erectile dysfunction to accurately establish an effect of nut consumption on erectile function and cardiovascular risk.…”

Health Benefits of Nut Consumption in Middle-Aged and Elderly Population

“…The effects of tree nut and peanut consumption on lipid profiles from intervention studies published in the last ten years [31,32,33,34,35,36,37,38,39,40,41,42,43] are summarized in Table 2. The results of these clinical trials in a middle-aged population indicate a causal association between higher nut intake and lower levels of total cholesterol (T-C), low density lipoprotein-cholesterol (LDL-C), non-high density lipoprotein-cholesterol (non-HDL-C), triglycerides (TG), and apolipoprotein B (apoB), all markers of CV morbidity and mortality.…”

“…A new trial confirmed that, compared to a carbohydrate control diet, adding 75 g per day of mixed nuts (tree nuts and peanuts) to healthy diets could significantly lower small LDL-C ( p = 0.018), with a trend towards reduction for T-C ( p = 0.066) and non-HDL-C ( p = 0.067) in T2DM elderly patients [42].…”

“…The outcome of tree nut and peanut consumption on biochemical and anthropometric parameters found in clinical trials published in the last ten years [31,41,42,54,55,56,57,58,59,60] are summarized in Table 3.…”

“…An RCT conducted on patients with diabetes established that 75 g mixed nuts (tree nuts and peanuts) added to the diet for 3 months, besides improving the lipid profile, also significantly lowered HbA1c compared with a carbohydrate diet ( p = 0.026) [42]. In another trial conducted on T2DM subjects, the addition of 15 mL walnut oil to the diet for three month significantly decreased HbA1c level by 7.86% ( p = 0.005) and fasting blood glucose by 8.24% ( p = 0.001) compared to control [61].…”