Scientists in the US suggest that a diet rich in alpha-linolenic acid found in walnuts, walnut oil and flaxseed oil not only lowers bad cholesterol, but could also impact a marker of inflammation for heart health.
This is the first study to demonstrate that a diet high in walnuts decreases C-reactive protein (CRP), a marker of inflammation strongly associated with heart disease, say the researchers.
"This research shows that walnuts, with their unique nutrient profile, can play a role in reducing cardiovascular risk factors as part of eating plans that also control saturated fat, trans fat, dietary cholesterol and calories," said Dr Penny Kris-Etherton, a professor of nutrition at Penn State University who led the study.
Walnuts, one of the oldest food ingredients known to mankind, could help flagging volumes for cake producers. Although the UK cake market has risen in value by 3.8 per cent since 2003, this is mainly a reflection of higher prices and not increased sales, say market analysts Mintel of the UK market.
But by contrast the UK functional food market, which cake makers could grab a slice of, is showing strong growth with Mintel predicting the £835 million market will double in the next five years to £1.7 billion with heart disease and breast cancer topping the list of consumer health concerns.
A relatively stable crop, prices for walnut kernels are currently in the range of $4,000 a tonne to $6,000 a tonne on supplies from California, China, eastern Europe, Turkey, India, France, Kashmir, Italy and Chile. On the back of quality and supply issues Californian walnuts come in at the top end of the price range.
Dutch firm IMKO ingredients, a leading nut player, told FoodNavigator.com that recent price hikes for pecan nuts are firming up walnut prices as manufacturers turn to alternative nut mixes to reduce expenses.
A result of recent hurricanes that severely damaged US pecan crops, prices for pecans are pushing $10,000 a tonne at the far end of the range.
The small Penn State study included 20 men and 3 women, average age about 50, who were overweight, had moderately elevated cholesterol and LDL cholesterol and were representative of individuals at risk for cardiovascular disease. On average their total cholesterol was 225, LDL cholesterol 154, HDL cholesterol 45 and triglycerides 137 mg/dl.
Participants ate three experimental diets that provided about 35 per cent of total calories as fat, consuming each diet for six weeks. One diet approximated the average American diet (AAD), another, the linoleic acid (LA) diet, that included an ounce of walnuts and a tablespoon of walnut oil that provided about 12.6 per cent of calories from linoleic acid and 3.6 per cent of calories from alpha-linolenic acid.
The third, the alpha-linolenic acid (ALA) diet, included the walnuts and walnut oil as well as a teaspoon of flaxseed oil to boost the content of alpha-linolenic acid. The fat content was 10.5 per cent of calories from linoleic acid and 6.5 per cent from alpha-linolenic acid.
"Compared to the average American diet, both the LA and the ALA diets lowered total cholesterol about 11 per cent, LDLs about 11 or 12 per cent and triglycerides about 18 per cent," report the researchers.
After six weeks on the diet, CRP declined after both the LA and ALA diets but more so on the ALA diet. Some participants had a dramatic reduction in CRP, they add.
Kris-Etherton commented: "It will be important to determine whether there is a genetic basis for this different CRP response. "
Full findings for the study are published in the November issue of the Journal of Nutrition.