The compound pterostilbene has the potential to be developed into a nutraceutical for lowering cholesterol, particularly for those who do not respond well to conventional drugs used for this purpose, say the researchers.
Presenting their findings this week at the annual American Chemical Society meeting, the study authors from the US government-backed Agricultural Research Service (ARS) say the blueberry compound could be a potent weapon in the battle against obesity and heart disease through its cholesterol-reducing potential.
Increased levels of LDL cholesterol, also known as 'bad' cholesterol, are known to contribute to atherosclerosis, the narrowing and hardening of the arteries, a condition that is related to increased chances of heart attack.
Pterostilbene is similar to resveratrol, another antioxidant identified in grapes and red wine that is also believed to lower cholesterol. Other researchers have found pterostilbene in grapes, but this is the first time it has been found in blueberries, commented lead researcher Agnes M. Rimando. She and her associates earlier showed that this compound may help fight cancer.
Cardiovascular disease made up 16.7 million, or a considerable 29.2 per cent, of total global deaths according to the World Health Report 2003 from the UN-backed World Health Organisation (WHO).
National governments are looking to change in dietary habits as a way to ease the escalation of CVD because high blood pressure, high blood cholesterol, overweight and obesity - and the chronic disease of type 2 diabetes - are among the major biological risk factors.
A range of cholesterol-lowering food products is already on the market, developed by pharma and food ingredients firms to target the growing demand from consumers.
Last month Canadian company Forbes Medi-Tech received a positive opinion from European authorities for the approval of its wood-derived cholesterol-lowering ingredient Reducol, joining a list of new EU-approved plant sterol ingredients and applications from US-based Archer Daniels Midland (ADM), food giant Unilever (with its Flora ProActiv range), and the smaller Finnish firms Teriaka and Pharmaconsult.
The market for heart health foods is forecast for rapid growth and seems to have room for new ingredients, especially given the slow process for approval of phytosterols until recently.
A Frost & Sullivan report on plant sterols forecasts growth between now and 2010 at 15 per cent annually, partly boosted by faster regulatory approval. (New applications can be cleared faster based on their similarity to previous approvals).
"We are excited to learn that blueberries, which are already known to be rich in healthy compounds, may also be a potent weapon in the battle against obesity and heart disease," said blueberry study leader Rimando at ARS.
In the recent ARS study, rat liver cells were exposed to four compounds found in blueberries. Of the four compounds, pterostilbene showed the highest potency for activating the cells' PPAR-alpha receptor, which in turn plays a role in reducing cholesterol and other lipids.
"Pterostilbene was similar in activity to ciprofibrate, a commercial drug that lowers LDL (bad) cholesterol and triglycerides. But ciprofibrate, whose mechanism of action on cells is less specific, can have side effects such as muscle pain and nausea. Pterostilbene, which targets a specific receptor, is likely to have fewer side effects," said Rimando.
The compound did not show any signs of cell toxicity in preliminary studies.
But human trials need to be conducted to establish how many blueberries a person needs to eat to have a positive effect at lowering cholesterol.