Nuts on cholesterol

The more nuts you eat, the lower your cholesterol, a new study appears to suggest.

Researchers at the Lorna Linda University in California found that people who replaced 20 per cent of their energy intake with almonds had a markedly improved blood lipid profile.

Scientists have previously reported that frequent consumption of nuts may lower the risk of cardiovascular disease by altering serum lipid and lipoprotein concentrations.

The new study compared the effects of the US 'National Cholesterol Education Program Step I diet', which restricts the total fat intake to 30 per cent of daily calories, saturated fat to 10 per cent, and dietary cholesterol to 300mg/day, with two other diets including almonds - a low-almond diet (replacing 10 per cent of total energy with the nuts) and a high-almond diet (where nuts made up 20 per cent of total energy).

In a randomised crossover design, 25 healthy subjects or adults with slightly raised cholesterol levels (14 men, 11 women), aged 41 on average, were fed the three isoenergetic diets for four weeks each, after being fed a two-week run-in diet (containing 34 per cent of energy from fat). Serum lipids, lipoproteins, apolipoproteins, and glucose were assessed.

Inverse relations were observed between the percentage of energy in the diet from almonds and the subject's total cholesterol, LDL-cholesterol, and apolipoprotein B, report the researchers in the June issue of the American Journal of Clinical Nutrition​. The same was seen in concentrations and the ratios of LDL to HDL cholesterol and of apolipoprotein B to apolipoprotein A. Compared with the Step I diet, the high-almond diet reduced total cholesterol by 4.4 per cent, LDL cholesterol by 7 per cent and apolipoprotein B 6.6 per cent. HDL cholesterol increased 1.7 per cent and the ratio of LDL to HDL cholesterol decreased nearly 9 per cent, said the researchers.

They added that there could be a dose-response relation between the nuts and total and LDL-cholesterol, which declined with progressively higher intakes of almonds.

The researchers also found that despite the addition of almonds to the diet, participants maintained their weight.

"In addition to reducing LDL cholesterol, the high-almond diet also illustrated decreases in the risk factors of cardiovascular disease,"​ said Dr Joan Sabate, the study's lead author. "While the monounsaturated fats in almonds are beneficial for heart health, our research also found that other nutrients in almonds may reduce cardiovascular disease risk factors as well. For instance, almonds have a high concentration of the alpha-tocopherol form of vitamin E, an antioxidant that has been associated with lower risk of heart disease."​

Almonds are also a good source of protein that is rich in arginine, added Sabate. Arginine is a precursor to nitric oxide that is known to inhibit platelet adhesion. Almonds also contain dietary fibre, phytosterols, and other phytochemicals that may have cardio-protective effects.

"Many cholesterol-lowering diets are restrictive, allowing for little total and saturated fat, and are difficult to maintain in the long run. This research shows that just a handful of almonds a day supplies healthy monounsaturated fats and other beneficial nutrients for a healthy heart,"​ added Sabate.