A randomized, controlled trial on the effects of almonds on lipoprotein response to a higher carbohydrate, lower fat diet in men and women with abdominal adiposity

Abstract

Background: Almonds have been shown to lower LDL cholesterol but there is limited information regarding their effects on the dyslipidemia characterized by increased levels of very low density lipoproteins (VLDL) and small, dense low-density lipoprotein (LDL) particles that is associated with abdominal adiposity and high carbohydrate intake. The objective of the present study was to test whether substitution of almonds for other foods attenuates carbohydrate-induced increases in small, dense LDL in individuals with increased abdominal adiposity.

Methods: This was a randomized cross-over study of three 3wk diets, separated by 2wk washouts: a higher-carbohydrate (CHO) reference diet (CHOhigh), a higher-CHO diet with isocaloric substitution of 20% kcal (E) from almonds (CHOhigh + almonds), and a lower-CHO reference diet (CHOlow) in 9 men and 15 women who were overweight or obese. The two CHOhigh diets contained 50% carbohydrate, 15% protein, 35% fat (6% saturated, 21% monounsaturated, 8% polyunsaturated), while the CHOlow diet contained 25% carbohydrate, 28% protein, 47% fat (8% saturated, 28% monounsaturated, 8% polyunsaturated). Lipoprotein subfraction concentrations were measured by ion mobility.

Results: Relative to the CHOlow diet: 1) the CHOhigh + almonds diet significantly increased small, dense LDLIIIa (mean difference ± SE: 28.6 ± 10.4 nmol/L, P = 0.008), and reduced LDL-peak diameter (- 1.7 ± 0.6 Å, P = 0.008); 2) the CHOhigh diet significantly increased medium-sized LDLIIb (24.8 ± 11.4 nmol/L, P = 0.04) and large VLDL (3.7 ± 1.8 nmol/L, P = 0.05). Relative to CHOlow, the effects of CHOhigh on LDLIIIa (17.7 ± 10.6 nmol/L) and LDL-peak diameter (- 1.1 ± 0.6 Å) were consistent with those of CHOhigh + almonds, and the effects of CHOhigh + almonds on LDLIIb (21.0 ± 11.2 nmol/L) and large VLDL (2.8 ± 1.8 nmol/L) were consistent with those of CHOhigh, but did not achieve statistical significance (P > 0.05). None of the variables examined showed a significant difference between the CHOhigh + almonds and CHOhigh diets (P > 0.05).

Conclusion: Our analyses provided no evidence that deriving 20% E from almonds significantly modifies increases in levels of small, dense LDL or other plasma lipoprotein changes induced by a higher carbohydrate low saturated fat diet in individuals with increased abdominal adiposity.

Trial registration: Clinicaltrials.gov NCT01792648 .

Keywords: Almonds; High carbohydrate; Lipids; Lipoprotein size; Triglycerides.

Conflict of interest statement

Ethics approval and consent to participate

This study was conducted according to the guidelines laid down in the Declaration of Helsinki and the procedures involving human subjects were approved by the Children’s Hospital and Research Center Oakland Institutional Review Board. Written informed consent was obtained from all subjects.

Consent for publication

Not applicable.

Competing interests

RMK and NB are recipients of a grant from Dairy Management Inc., but this grant is not for the submitted work; RMK holds licensed patents for ion mobility analyses.

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Figures

Fig. 1

Participant enrollment