By TAP Integrative

Higher concentrations of HDL cholesterol are associated with a decreased risk of cardiovascular disease, but evidence suggests that the cardioprotective effects of HDL depend more on HDL function and HDL subspecies than on absolute HDL concentrations. HDL function refers to actions such as reverse cholesterol transport from the periphery to the liver, a process that begins with cholesterol efflux from macrophages. HDL subspecies (including pre-β-1, pre-β2, α-1, α-2, α-3, and α-4) refer to HDL molecules that vary in size, density, and apolipoprotein composition.

Data from the Framingham Offspring Study showed that higher concentrations of α-1 HDL decreased the odds of ischemic heart disease, whereas higher concentrations of α-3 HDL increased the odds. Additional studies show that low concentrations of α-1 HDL and high concentrations of pre-β-1 HDL, alone or in combination, increase cardiovascular risk.

Researchers at Pennsylvania State University hypothesized that eating almonds in the context of a cholesterol-lowering diet would improve HDL function and HDL subspecies compared with a traditional cholesterol-lowering diet. To test this hypothesis, they analyzed stored samples from a previous controlled feeding trial.

The previous trial had demonstrated that a diet providing almonds (43g, or approximately 35 almonds per day) improved total HDL concentrations when compared with a similar diet providing an isocaloric muffin in place of almonds. The macronutrient content of the almond diet was 51% carbohydrate, 16% protein, 32% total fat, and 8% saturated fat. The macronutrient content for the control diet was 58% carbohydrate, 15% protein, 26% total fat, and 8% saturated fat.

In the overall analysis of samples, the almond diet improved α-1 HDL compared with the control diet. Subgroup analysis revealed that this effect was only observed in normal-weight individuals. In normal-weight individuals, the almond diet increased α-1 HDL, increased the α-1 to pre-β-1 ratio, increased non-ATP cassette transporter A1 cholesterol efflux, decreased pre-β-2 HDL, and decreased α-3 HDL. None of these effects were observed in the overweight or obese subgroups.

The authors conclude that in normal-weight individuals, almonds in the context of a cholesterol-lowering diet improve HDL subspecies by preventing the decrease in α-1 HDL caused by traditional low-fat diets.


Berryman CE, Fleming JA, Kris-Etherton PM. Inclusion of Almonds in a Cholesterol-Lowering Diet Improves Plasma HDL Subspecies and Cholesterol Efflux to Serum in Normal-Weight Individuals with Elevated LDL Cholesterol. J Nutr. 2017;147(8):1517-1523.


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