Cholesterol-Reducing Compounds Found in Citrus

An ongoing search for profitable new uses for food-processing byproducts has led Agricultural Research Service (ARS) scientists to focus on citrus waste. They've recently learned that a compound found in orange oil decreases blood serum levels of the protein responsible for low-density lipoprotein (LDL) that's a major cholesterol carrier.

Chemist John A. Manthey, at the ARS Citrus and Subtropical Products Research Laboratory in Winter Haven, Fla., has done extensive research on flavonoids in citrus peel byproducts. He has focused on the polymethoxylated flavones, or PMFs, which typically occur at very high concentrations in the oil that's in orange peel residue.

In Florida, about 700,000 tons of dried peel solids are left over from squeezing around 150 million boxes of juice oranges every year, on average. Most of this processing waste is now sold for livestock feed at little or no profit to citrus processors.

Manthey's research has shown that the PMFs decrease blood serum levels of apoprotein B, the structural protein of LDL cholesterol. Too much circulating LDL cholesterol can slowly lead to atherosclerosis, clogged arteries and eventual heart attacks and strokes. These problems are accelerated by chronic, low-grade inflammation in the blood vessels.

For the past eight years, Manthey has collaborated with KGK Synergize of London, Ontario, Canada, a company that specializes in research to identify health-promoting compounds and focuses on nutraceuticals. Sometimes called functional foods, nutraceuticals are natural, bioactive chemical compounds with disease-preventing or medicinal properties. Nutraceuticals are being commercially produced by food, pharmaceutical, and herbal and dietary supplement industries.

The original collaboration between ARS and KGK Synergize involved studies of the anticancer properties of citrus PMFs, but it subsequently expanded into in vitro investigations of the abilities of PMFs to lower LDL-cholesterol in animals.

Read more about the research in the September issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief in-house scientific research agency.