- Almonds (Prunus dulcis, Rosaceae)
- Coronary Artery Disease
- Serum Uric Acid
Higher serum levels of uric acid (UA) are increasing in prevalence globally and are associated with coronary artery disease (CAD) and a higher risk of heart attack or stroke in patients with no history of heart disease and stroke. An increase of 1 mg/dL in serum UA has been found to cause a 12% increase in the risk of CAD mortality. Almonds (Prunus dulcis, Rosaceae) are recognized for their lipid-neutralizing effects and may reduce the risk of cardiovascular disease (CVD). A previous study found almond supplementation to prevent hyperuricemia in a CVD rat model. The goal of this randomized controlled trial (RCT) was to evaluate the UA-reducing potential of almond supplementation in patients with CAD.
The study recruited 150 patients with CAD from the Cardiology Clinic, Aga Khan University Hospital; Karachi, Pakistan. Patients who regularly consumed nuts or had nut allergies were excluded. Patients were randomly assigned into 1 of the following 3 groups of 50: no intervention (NI), supplementation with almonds grown in Pakistan (PA), and supplementation with imported American almonds (AA). Patients in the NI group were asked to abstain from consuming any nuts, specifically almonds, while enrolled in the RCT. Those in the PA and AA groups were given 10 g/day almonds and told to prepare them traditionally—soak overnight, peel, and eat before breakfast daily. Patients kept consumption diaries and compliance was monitored in twice-weekly phone calls. At baseline, blood was drawn and body weight, blood pressure (BP), and other measures were taken. Follow-up visits were scheduled at 6 and 12 weeks with the same measurements taken. Patients in the NI group received almonds at the end of the RCT.
Baseline demographics and serum UA were similar in all the groups (P>0.05). Patient weight and BP remained fairly constant in all groups throughout the 12-week study. At week 6, men in the PA group had a 15% reduction in UA, and women had a 12% reduction in UA, compared to the NI group (P<0.05). Men in the AA group had 17% less serum UA, and women 19% less, compared to NI (P<0.05). At week 12, men in the PA group had 17% less serum UA, and women 16% less, than those in the NI group (P<0.05). In the AA group at the end of the study, men had 20% less serum UA, and women 21% less, compared to NI (P<0.05). Compared to baseline, patients in the NI group showed negligible decreases in serum UA, whereas both the PA and AA groups had significant improvement (P<0.05) at both follow-up visits. Men in both active groups had 13% less serum UA at 6 weeks; women in the PA group, 11% less; and women in the AA group, 16% less. At 12 weeks, men in the PA group had improved 16% over baseline and women in the PA group had improved by 14%; and men and women in the AA group had 18% less serum UA than at baseline. This is the first almond intervention study in patients with CAD reporting on UA reduction.
Serum UA may be considered as a marker for vascular function, with anticipated pathways of damage including pro-oxidative and proinflammatory factors among others. Almond supplementation is known to positively affect some of these factors, including a possible reduction in C-reactive protein reported in some studies. Almonds contain L-arginine, a precursor of nitric oxide that has been reported to reduce BP in vivo. In this RCT, almost all patients were taking antihypertensive medications and no effect on BP was seen.
It should be noted that while this study differentiated between Pakistani and American almonds, and those in the AA group showed slightly more improvement than those in the PA group, there is no botanical difference between these almonds. Differences in constituents caused by time of harvest, a method of storage, and different cultivars might be considered in future studies. It should also be noted that the almond skin, discarded by patients in this study, is a rich source of vitamins and minerals, and possibly of other nutrients of interest. Future studies might compare effects of almonds with skins and those that have been peeled.
Jamshed H, Gilani AUH, Sultan FAT, et al. Almond supplementation reduces serum uric acid in coronary artery disease patients: a randomized controlled trial. Nutr J. August 19, 2016;15:77. doi: 10.1186/s12937-016-0195-4.