The purpose of this review was to examine the effect of nut consumption on blood lipids and lipoproteins.

Several causes of death and disability-adjusted life years worldwide are caused by cardiovascular diseases (CVD), including coronary heart disease (CHD) and stroke. In addition, there is a well-documented risk factor for atherosclerotic CVD (elevated levels of low-density lipoprotein cholesterol (LDL) or triglycerides (TG) in the blood, a decrease in high-density lipoprotein cholesterol (HDL), or other lipoprotein disturbances).

A key step towards improving the health of populations is the development of effective prevention strategies for CVD, including changes in lifestyle and diet.

Preventing and treating CHD and other atherosclerotic diseases relies heavily on dietary interventions to lower blood cholesterol concentrations and modify blood lipoprotein levels. Yet, between 1990 and 2016, one in five premature deaths worldwide was attributed to suboptimal dietary intake.

More deaths were associated with suboptimal diets than any other risk factor in the United States (U.S.). According to the American Heart Association, dietary risk factors contributed to 529,300 deaths in 2016, 84% resulting from cardiovascular disease. 

Additionally, in 2017, a diet low in nuts and seeds was the fourth leading cause of death worldwide, after a diet low in whole grains, a diet high in sodium, and a diet low in fruits.

Methodology

Among the 19 systematic reviews and meta-analyses found in PubMed between the inception date and November 2022, 19 were systematic reviews and meta-analyses, respectively. 

It has been consistently reported across meta-analyses that most nuts, including walnuts, almonds, cashews, peanuts, and pistachios, have a positive effect on lowering total cholesterol, LDL cholesterol, and triglycerides.

However, no effect has been found on HDL cholesterol levels. In addition, preliminary research indicates that nuts reduce blood levels of apolipoprotein B and improve HDL function. In addition, nuts have been shown to improve lipids and lipoproteins in a dose-dependent manner.

Nut consumption has been linked to various health benefits in recent decades, including reduced risk and prevention of cardiometabolic diseases. This makes nuts a key dietary recommendation for promoting health and preventing disease. 

However, there is an inverse correlation between frequent nut consumption and type 2 diabetes, metabolic syndrome, cardiovascular disease, and total and cause-specific mortality in large prospective cohort studies.

Lower body mass index and higher baseline lipid concentrations enhance blood lipid/lipoprotein responses, while sex, age, or nut processing do not modify the effects. Even though research is still in its infancy, nut-enriched diets have been associated with lower levels of total LDL particles and smaller, dense LDL particles.

Conclusion of the Study

As a result of clinical trials, evidence has demonstrated that the consumption of whole nuts and certain types of nuts has positive effects on blood lipid profiles through multiple mechanisms. In particular, nut-enriched diets reduce total cholesterol, LDL-C, and cholesterol levels in comparison to control diets.

Some RCTs have also shown benefits in reducing ApoB levels and improving the lipoprotein sub-particle profile. The major determinant of cholesterol-lowering appears to be nut dose rather than nut type.

Nut consumption must be increased by effectively educating consumers about nuts’ health benefits and, importantly, by demonstrating how nuts can be substituted for unhealthy foods to achieve the greatest possible benefit against CVD.

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