"As the fiber-rich pomace is available in large quantity in juice production, it is worth exploiting the carrot insoluble fiber-rich fractions (IFRF) as a promising hypocholesterolemic ingredient to fulfill the increasing demand of functional ingredients in developing fiber-rich food products," wrote lead author Pang-Kuei Hsu in the journal LWT - Food Science and Technology (Vol. 39, pp. 337-342).
High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), which affected 34.2 percent of Americans (70.1 million people) in 2002, according to the American Heart Association.
The authors, from the National Chung Hsing University and the Yuan Pei University of Science and Technology, obtained carrot waste from the carrot juice extraction process and investigated the effect of supplementing the diets of six week old hamsters with the waste.
Twenty-four hamsters were divided into three groups, and had their standard diet supplemented with one of the following: nothing (fiber-free control group); cellulose (5g per 100 g); or the carrot IFRF (5.69g per 100g). All diets were supplemented with cholesterol (1g per 100g).
After 30 diets on each diet, the researchers found that: "incorporation of cellulose and IFRF into the fiber-free diet significantly reduced the serum total cholesterol levels by 17.3 per cent and 33.5 per cent, respectively."
While the IFRF diet also reduced levels of high-density lipoprotein (so-called 'good') cholesterol (HDL-C) by 20 per cent, the ratio of HDL:total cholesterol was higher for both supplementation groups.
"It was desirable that the HDL:total cholesterol ratio for the IFRF group was higher than that for the fiber-free group because there was a negative correlation between the HDL:total cholesterol ration and the risk of CVD," said Hsu.
Serum triglyceride concentrations in the hamsters blood also decreased as a result of the IFRF diet, and less so with the cellulose diet.
The researchers did not investigate the mechanism behind the effects of the carrot waste but proposed that it could be due to a combination of effects including decreased transit time, lower fat and cholesterol absorption, and increased breakdown of the cholesterol to bile acids.
The combination of cheap availability and the preliminary results of this laboratory-based study led the researchers to propose that the waste from carrot juicing could be a promising cholesterol-lowering functional ingredient.
According to Frost and Sullivan, the entire fiber market in the US was worth $192.8 m in 2004, $176.2 m of which is insoluble fiber and $16.6 m soluble.
But while Frost and Sullivan predicts overall growth to $470 million by 2011, the soluble fiber sector is expected to increase by almost twice the compound annual growth rate (CAGR) compared to insoluble fiber - 26.3 percent compared to 13.1 percent.
Despite these impressive sales figures, many Americans are falling well short of the 32 grams of fiber recommended by the National Fiber Council. According to a survey by Columbia University, the average intake was about 12.5 grams a day.