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Nuts, CVD and Diabetes: Updated

Apr 30, 2019
 

Author: Steve Freed, R.PH., CDE


To date, there is limited evidence concerning the potential health benefits of eating nuts for persons with T2D.

Nuts contain many unsaturated fatty acids, plant proteins, fiber, minerals, vitamins, and phytochemicals (phytosterols, flavonoids, and phenolic acids) shown to benefit health by improving lipid profiles, insulin resistance, oxidative stress, inflammation, and vascular reactivity. Several meta-analyses of prospective cohort studies in the general population have linked frequent nut consumption to lower risk of developing hypertension, CVD, total cancer, and all-cause and cause-specific mortality.

 

The goal of this prospective study was to evaluate associations of consuming total and specific types of nuts, including tree nuts and peanuts, with subsequent risk for CVD, including CHD and stroke, and all-cause and cause-specific mortality among persons with diabetes who were enrolled in the Nurses’ Health Study (NHS) (1980-2014) or Health Professionals Follow-Up Study (HPFS) (1986-2014).

According to a study published online in Circulation Research, eating nuts may decrease the risk for CVD and death in people with T2D. The researchers found that higher levels of nut consumption — especially tree nuts such as walnuts, cashews, and almonds — were tied to greater reductions in cardiovascular (CV) risk.

The findings provide new evidence that supports the recommendation of including nuts in healthy dietary patterns for the prevention of CVD complications and premature deaths among individuals with diabetes.  

When looking at nut consumption in individuals with diabetes, past studies have linked consumption of nuts to a reduction in a variety of CV risk factors, such as high blood pressure, abnormal lipid levels, insulin resistance, and inflammation. The PREDIMED trial, one of the largest randomized controlled trials to evaluate the effect of nuts on CV health, found a reduced risk for CVD in persons randomly assigned to a Mediterranean diet plus nuts compared with control participants.

There have been a number of studies looking at the benefits of nuts in the prevention of CVD, but few studies have looked at the issue in the specific population.of people with diabetes, who are already at increased risk for CVD. To shed additional light, first author Gang Liu, PhD, of the Harvard T.H. Chan School of Public Health, Boston, Massachusetts, and colleagues examined data from 2 prospective studies: one included data from 1980 to 2014 from the NHS and the other from 1986 to 2014 from the HPFS.  The analysis included 16,217 people who had diabetes at baseline or were diagnosed with it during the studies. Participants answered questions about nut consumption using validated food frequency questionnaires every 2 to 4 years.

Results showed that eating 5 or more 28-g servings of nuts per week was linked to a 17% lower risk for CVD, a 34% lower risk for CVD death, a 20% lower risk for CHD, and a 31% lower risk for death from all causes compared with eating less than one serving per month.  For each one-serving increase in total nuts per week, the risk for CVD decreased by 3% and the risk for death from CVD decreased by 6% (P<.001).  More specifically, eating higher levels of tree nuts was linked to a lower risk for CVD, CHD, death because of CVD, cancer, and all-cause death (P<.001).  These observations did not apply to peanuts. The only outcome that was significantly reduced with increasing levels of peanut consumption was all-cause death (P<.001).

Some added benefits include that people who started eating more nuts after their diabetes diagnosis had additional benefits of an 11% lower risk for CVD, 15% lower risk for CHD, 25% lower risk for death from CVD, and 27% lower risk for death from all causes compared with people who did not increase their nut consumption after diagnosis.  Again, tree nut consumption was linked to even greater reductions in risk in this group. Results were unchanged after adjusting for several established risk factors for CVD, including diabetes duration, body mass index (BMI), medication use, nut consumption before diabetes diagnosis, exercise, and diet. The authors noted that the reason for the difference between tree nuts and peanuts is unclear but may have to do with higher levels of healthy nutrients in tree nuts. Peanuts are actually legumes, not nuts, and so have a different nutritional composition.

This new evidence supports the recommendation that persons with diabetes should include nuts in healthy dietary patterns to help prevent CVD complications and premature deaths.  Clinical trial data suggest that nut consumption may improve glycemic control, blood pressure, lipid metabolism, inflammation, and endothelial dysfunction in persons with diabetes.

Practice Pearls

  • Nuts provide an excellent source of healthy nutrients, such as unsaturated fatty acids, plant proteins, fiber, minerals, vitamins, and anti-inflammatory phytochemicals.
  • Higher total nut consumption was associated with lower risk for CVD incidence and mortality but was not significantly associated with risk for stroke incidence or cancer mortality.
  • Higher tree nut consumption was associated with lower risk for total CVD; CHD incidence; and mortality from CVD, cancer, and all causes, but peanut consumption was associated only with lower all-cause mortality (P trend <.001 for all).

 

Liu G, Guasch-Ferre M, Hu Y, et al. Nut consumption in relation to cardiovascular disease incidence and mortality among patients with diabetes mellitus.Circ Res. 2019https://www.ahajournals.org/doi/pdf/10.1161/CIRCRESAHA.118.314316. February 25, 2019.Circ Res. 2019. Published online February 19, 2019.]