A recent study in the American Journal of Clinical Nutrition found that consuming 57 grams of pecans daily for 12 weeks improved lipid/lipoprotein levels and diet quality, but did not affect vascular health in adults at high risk for cardiometabolic disease.
How snacking affects heart health and metabolism
In the United States, approximately 45% of cardiometabolic disease-related deaths are associated with poor diet quality. Therefore, adhering to a healthy dietary pattern over the long term can effectively reduce the risk of death from cardiometabolic disease.
Snacks are an important meal because they provide approximately 20% of total daily energy intake. However, people who consume snacks high in added sugars and saturated fats generally have poorer overall diet quality than those who eat nutrient-dense foods when snacking. This suggests that replacing nutrient-poor snacks with nutrient-dense alternatives can improve diet quality and health outcomes.
Nuts as a Healthy Snack
Nuts are a nutrient-dense food that can be eaten as a snack instead of unhealthy foods. Multiple epidemiological studies have shown that nut intake is associated with a reduced risk of cardiovascular disease (CVD). Similarly, multiple clinical trials have reported that nut intake improves CVD risk factors, particularly triglycerides, glycemic index, low-density lipoprotein (LDL) cholesterol, and endothelial function, in adults with various health conditions.
Compared to other nuts, pecans are higher in polyphenols, including flavan-3-ols. Studies have shown that high intakes of flavan-3-ols are associated with a reduced risk of coronary artery disease and cardiovascular death. This polyphenol also improves endothelial function as measured by flow-mediated dilation (FMD).
Pecan consumption has also been associated with improved lipid and lipoprotein levels compared to non-nut snacks. However, one clinical trial reported that pecan consumption had no positive effect on FMD in older adults, which contradicts this finding. These conflicting results require further research to clarify the impact of pecans on cardiovascular health.
About the Study
The current single-blind, randomized, parallel, and controlled clinical trial was conducted at Pennsylvania State University from August 2022 to March 2024. The researchers hypothesized that consuming 57 grams of raw, unsalted pecans daily would improve FMD, lipids/lipoproteins, arterial stiffness, and glycemic control compared with those who continued to consume a normal diet.
All eligible participants were randomized 1:1 to either a pecan snack group or a regular diet group. Male and female participants were aged 25 to 70 years and were overweight or obese. All study participants had at least one type of metabolic syndrome at screening.
Individuals with an allergy or sensitivity to pecans, tobacco use within six months prior to the start of the study, a history of cardiovascular events or heart failure, type 2 diabetes, or other medical conditions were not eligible for study participation.
Vascular and cardiometabolic outcomes were assessed at baseline and after 12 weeks of intervention. Diet quality was measured at baseline, week 6, and week 12.
Study Results
Overall, 59% of study participants were female, with a mean age of 46 years and a mean body mass index (BMI) of 29.8 kg/m 2. At baseline, 38 study participants met criteria for metabolic syndrome, and 89% reported snack intake on a 24-hour recall survey. Energy intake from snacks was similar in both groups.
In the pecan group, study participants consumed pecans as a snack on a median of 100% of study days. At week 12, neither study group was significantly associated with FMD or any secondary vascular measures.
After 12 weeks, the pecan group had gained an average of 0.85 kg in weight compared with baseline levels. Those who gained weight in the pecan group had a greater decrease in pulse pressure than those who gained weight in the normal diet group. No intervention heterogeneity of weight change status on cardiometabolic risk factors was observed in either group.
After 12 weeks, participants who consumed pecans had improved levels of total cholesterol, LDL cholesterol, triglycerides, and non-high-density lipoprotein (HDL) cholesterol compared to the usual diet group. After 12 weeks, the pecan group had higher intakes of total fat, monounsaturated fat, polyunsaturated fat, and fiber than the usual diet group. Participants who consumed pecans also consumed less energy from carbohydrates.
Pecan consumption was associated with improvements in overall diet quality, as assessed by the Healthy Eating Index (HEI)-2020. After 12 weeks, the pecan group had a 9.4-point higher HEI-2020 score than the usual diet group.
Conclusion
The study found that pecan consumption could improve lipids/lipoproteins and diet quality, which could positively reduce cardiovascular disease risk in adults at increased risk for cardiometabolic disease. While pecan consumption did not affect vascular health, the researchers in this study recommend replacing a typical snack with 57 g/day of pecans.
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