True tree nuts (note peanuts are legumes) have been shown to have a number of health benefits when consumed regularly. In particular, nuts are a rich source of antioxidant nutrients, and these are concentrated in the nuts to protect the mainly unsaturated fatty acid content of the nuts from rancidity. When humans and animals eat the nuts, these antioxidants may be absorbed, where they are incorporated into the individual’s own tissues. This endogenous supply of antioxidant then works synergistically with the endogenous antioxidants in the tissues, providing a complex interactive system of antioxidant defences. Consumption of nuts has been shown to improve blood lipid levels in humans and while this may relate to the antioxidants within nuts, the fatty acids may also play a role in this effect. Polyunsaturated and monounsaturated fatty acids may affect the fatty acid metabolism within the liver, thus altering the endogenous synthesis of lipids, and thus altering cholesterol metabolism and transport.
Studies have consistently shown beneficial changes to blood lipids following ingestion of tree nuts. Almonds for example have been shown to have beneficial effects on high density lipoprotein (HDL) cholesterol levels in humans. In one such study, researchers fed a number of subject with coronary artery disease either 10 grams of Pakistani almonds or 10 grams of American almonds. The results of the study showed that compared to no treatment, ingestion of almonds significantly increased HDL cholesterol in the subjects at weeks 6 and 12, with a 12 to 14 % increase following ingestion of Pakistani almonds and a 14 to 16 % increase following ingestion of American almonds. Because of the increase in HDL cholesterol, the total to HDL cholesterol and LDL to HDL ratios improved significantly in the patients as a group. These results therefore support previous research showing that almonds have particularly beneficial effects in human subjects that may significantly decrease the risk of cardiovascular disease.
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