Isoflavone-rich pasta effective to boost heart health - study
effectively reduce blood levels of total and LDL cholesterol by
about eight per cent, new research from Italy has reported.
The study, published in the October issue of the Journal of Nutrition, has implications for using soy isoflavones as functional ingredients for heart healthy foods, with the manufacturing process key to the natural enrichment of the pasta with isoflavone aglycons. During fermentation isoflavones change from the glucoside form to the aglycone form, said to be more bioavailable. A study by Yakult last year (The Journal of Nutrition, Vol. 136, pp. 2291-2296) stated that it made sense that aglycones are more bioavailable since they are smaller molecules and are more hydrophobic, and so do not dissolve as easily in water and thus rapidly excreted. "Most studies of soy and cholesterol have tested foods made from purified soy proteins containing mainly isoflavone glycosides," explained lead author Carlo Clerici from Universita degli Studi di Perugia. "The aim of this study was to compare a novel soy germ pasta, naturally enriched in isoflavone aglycons as a result of the manufacturing process, with conventional pasta for effects on serum lipids and other cardiovascular risk markers." The researchers recruited 62 adults with high cholesterol levels (hypercholesterolaemia) to take part in the randomised, controlled, parallel study. The participants were assigned to eat the Step II diet, created by the National Heart, Lung, and Blood Association's National Cholesterol Education Program (NCEP) and endorsed by the American Heart Association for eight weeks. The diet was formulated to include one 80-g serving/d of conventional or isoflavone-enriched pasta, providing 33 milligrams of isoflavones and negligible soy protein. Hypercholesterolaemia has a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year. After eight weeks, Clerici and co-workers report that blood levels of isoflavones were 222 nanomoles per litre. Consumption of the aglycone-enriched pasta led to reduction of total and LDL cholesterol levels in the blood of 7.3 and 8.6 per cent from baseline, respectively. These reductions were equivalent to reductions of 0.47 and 0.36 millimoles more than amongst people consuming conventional pasta. The soy pasta was also found to have benefits for arterial stiffness and C-reactive protein levels (CRP), a protein produced in the liver and is a known marker for inflammation. Increased levels of CRP are a good predictor for the onset of both type-2 diabetes and cardiovascular disease. The researchers state that the measures returned to initial levels when patients were switched to conventional pasta. "In conclusion, pasta naturally enriched with isoflavone aglycons and lacking soy protein had a significant hypocholesterolemic effect beyond a Step II diet and improved other cardiovascular risk markers," they stated. The research adds and expands the science behind the observed benefits that have previously been linked to the effect of isoflavones on blood cholesterol levels. However, this point is controversial and a recent scientific statement by the American Heart Association (AHA) in the journal Circulation concluded that soy had little effect on cholesterol levels, and raised doubts about health claims associated with soy. Source: Journal of Nutrition October 2007, Volume 137, Pages 2270-2278 "Pasta Naturally Enriched with Isoflavone Aglycons from Soy Germ Reduces Serum Lipids and Improves Markers of Cardiovascular Risk" Authors: Carlo Clerici, K.D.R. Setchell, P.M. Battezzati, M. Pirro, V. Giuliano, S. Asciutti, D. Castellani, E. Nardi, G. Sabatino, S. Orlandi, M. Baldoni, O. Morelli, E. Mannarino and A. Morelli
