Pecans lower cholesterol and improve diet quality in at-risk adults, study studies

Pecans lower cholesterol and improve diet quality in at-risk adults, study studies

Could a handful of pecans a day help your heart? A new clinical study shows that replacing snack foods with pecans significantly improves cholesterol levels and overall diet quality in adults without affecting blood vessel function.

In a recently published study inThe American Journal of Clinical NutritionResearchers examined the effects of pecan snacks on vascular health, cardiometabolic risk factors, and diet quality in individuals at risk of cardiometabolic diseases.

In the United States, cardiometabolic diseases remain the leading causes of death, and poor diet quality is a modifiable risk factor for these diseases. Higher adherence to healthy dietary patterns is associated with reduced risk of cardiometabolic diseases. However, adherence to healthy eating in the United States is poor. Nutrient-dense snacks contribute to improved diet quality, while snacks high in saturated fat and added sugar contribute to poor diet quality.

Nuts are an essential part of healthy dietary patterns, and higher nut consumption is associated with a reduced risk of cardiovascular disease (CVD). Pecans contain higher levels of polyphenols than other nuts, including flavan-3-ol. Increased intake of flavan-3-ols has been shown to reduce the risk of cardiovascular mortality and coronary artery disease.

About the study

In the present study, researchers examined the effects of replacing common snacks with pecans on diet quality, vascular health, and cardiometabolic disease risk factors. Participants were recruited between July 2022 and December 2023. Eligible subjects were adults aged 25 to 70 years with obesity or overweight who met at least one criterion for metabolic syndrome.

Participants were randomized into the pecan snack group or the usual diet group. The pecan group received 57 g/day of unsalted, raw pecans to replace their usual snacks, while the comparator group continued their regular diet. Participants completed daily questionnaires documenting their snack and pecan intake, changes in health status, and non-habitual medication use.

All subjects were instructed to avoid nonprescription medications and alcohol for 48 hours before testing. Central and peripheral blood pressure and carotid-femoral pulse wave velocity (CF-PWV) were measured on the test day and flow-mediated (FMD) was measured on a separate day.

Blood samples were collected and weight was measured on both test days. Glucose, glycated hemoglobin (Hba1c), lipids, lipoproteins, C-reactive protein (CRP), and insulin were also measured. Dietary intake was assessed using self-administered 24-hour food recalls at baseline and weeks 6 and 12. Diet quality was also assessed using the Healthy Eating Index (HEI)-2020.

It is important to note that participants in the control group were also instructed to avoid nuts (other than the intervention group's pecans) to prevent contamination of the intervention, which may have affected their diet quality scores.

Notably, baseline FMD values ​​were already relatively high in both groups, indicating normal endothelial function. This may have contributed to the lack of effect in vascular outcomes. Additionally, the estimated daily flavan-3-ol dose from pecans (~9 mg) was much lower than that shown in previous studies of vascular function benefits.

The improvement in lipid profiles observed in the pecan group may be attributed to dietary shifts such as:

Results

A total of 69 participants were assigned to each group. After 12 weeks, only 130 participants completed endpoint testing. At baseline, 89% of subjects reported snack intake for the 24-hour dietary recall. Median baseline energy intake from snacks was 294 kcal for the entire cohort. There were no significant differences in FMD between the two groups.

Likewise, there were no significant group differences for vascular measures at week 12. Further, there were no differences in the effect of intervention by weight change status for vascular outcomes except for pulse pressure. The subjects in the pecan group who experienced weight gain had a greater reduction in impulse pressure compared to the comparison group.

In addition, pecan recipients showed higher reductions in total cholesterol-cholesterol, lipoprotein cholesterol-cholesterol-cholesterol, triglycerides and total cholesterol-cholesterol-cholesterol ratio. There were no significant group differences in change from baseline for insulin, HDL cholesterol, CRP, HbA1c or waist circumference. In particular, there was no significant change in HDL cholesterol levels between groups.

No difference in weight change between groups was observed in the primary analysis. However, post hoc analyzes showed a modest but significant increase (~0.7 kg) in the pecan group. This modest weight gain may be due to incomplete energy substitution (i.e. pecans, which add more calories than snacks replace).

The mean HEI-2020 score at baseline was 56 points for both groups. After 12 weeks, the pecan group showed an increase of 9.4 points compared to the control group on a usual diet. This improvement was partly due to a reduction in diet quality in the usual diet group during the study, which may be related to instructions to avoid nuts. The pecan group had no differences in HEI-2020 scores between weeks 6 and 12. Baseline macronutrient and energy intakes were similar between groups. At week 12, the pecan group had a higher intake of fiber and fats than the usual diet group.

The reductions in LDL cholesterol (approximately 7 mg/dL or 6%) observed in the pecan group are considered clinically meaningful because such reductions have been associated with a lower risk of future vascular events.

The study authors also note several limitations, including reliance on self-reported dietary intake, discrimination to detect sex differences, and the potential for Type I statistical error due to multiple comparisons.

The American Pecan Council funded the study, although the funder had no role in study design, data collection, analysis, or interpretation.

Conclusions

In conclusion, 12 weeks of pecan intake in place of usual snacks did not affect FMD or other vascular measures in adults at risk of cardiometabolic diseases. However, pecan intake improved triglycerides and total, LDL, and non-HDL cholesterol levels compared to the usual diet group. There was no significant change in HDL cholesterol levels. Pecans also increased diet quality, although a slight weight gain was observed in the pecan group. These results suggest that replacing snacks with 57 g/day of pecans improves diet quality and lipids/lipoproteins, which may help alleviate the risk of cardiovascular disease (CVD) in individuals with cardiometabolic diseases.

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