The heart healthy effects of cruciferous vegetables like broccoli and cauliflower may be due to their ability to influence the secretion of a cholesterol transporter, researchers have reported.
The study, published in the Journal of Nutrition, significantly deepens our understanding of a class of vegetables more commonly linked to reducing the risk of certain cancers, especially lung, colon, breast, ovarian cancer, and, more recently, bladder cancer.
The research, led by Geoffrey K. Maiyoh from the University of Hawaii at Manoa, reports that the indole-based compound, indole-3-carbinol, was able to reduce the secretion of apolipoprotein B-100 (apoB) by 56 per cent, and thereby confer cardiovascular benefits.
ApoB is the main apolipoprotein of LDL cholesterol and is responsible for the transport of cholesterol to tissues. In high concentrations it has been linked to plaque formation in the blood vessels, although the mechanism behind this is not clear.
The study appears to be in-line with other studies reporting the cardiovascular benefits of the vegetables, including a meta-analysis published in The Lancet (Vol. 367, pp 320-326) that reported that eating five or more portions of fruit and vegetables per day could cut the risk of stroke by 26 per cent.
Cardiovascular health is an increasing topic of concern, and cardiovascular disease causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy an estimated €169 billion ($202 billion) per year.
According to the American Heart Association, 34.2 percent of Americans (70.1 million people) suffered from some form of cardiovascular disease (CVD) in 2002.
Maiyoh and co-workers performed in vitro experiments using HepG2 cells, and report that the indole-compound reduced secretion in a dose-dependent manner. Indeed, at a concentration of 100 micromoles per litre, apoB secretion was cut by 56 per cent, they said.
The researchers also report significant decreases in the production of lipids in the cells, including triglycerides and cholesterol esters, "indicating that limited lipid availability is a major factor in the regulation of apoB secretion."
"The results indicate that plant indoles have beneficial effects on lipid synthesis that could contribute to their potential cardioprotective effect," concluded the researchers.
The same compound has previously been identified as a possible bioactive constituent against cancers (British Journal of Cancer, Vol. 94, pp.407-426).
A report from the European Union showed that global fruit and vegetable production was over 1 230 million tonnes in 2001-2002, worth over $50 billion (€ 41 000 million). Asia produced 61 per cent, while Europe and North/Central America both producing nine per cent.
Source: Journal of Nutrition
October 2007, Volume 137, Pages 2185-2189
"Cruciferous Indole-3-Carbinol Inhibits Apolipoprotein B Secretion in HepG2 Cells1-3"
Authors: Geoffrey K. Maiyoh, J.E. Kuh, A. Casaschi and A.G. Theriault