Carotenoids more bioaccessible from fruit than green veg - study
green vegetables, says a new study from Ireland that has important
implications for the use of such ingredients in functional foods.
"As research focuses on the many health benefits associated with carotenoids, the in vitro digestion model used in the present study provides valuable information on the amount of these fat-soluble pigments that is potentially available for absorption by the gastrointestinal tract," wrote lead author Orla O'Connell from University College Cork.
The new study, published in the journal Nutrition Research , compared the in vitro bioaccessibility of carotenoids from a range of fruits and vegetables, including orange, kiwi, red grapefruit, and honeydew melon, and spinach, broccoli, red pepper, and sweet potato.
The Irish researchers used an in vitro digestion procedure to elucidate the bioaccessibility, defined by the researchers as the amount of the ingested compound available in the gastrointestinal tract for absorption, of beta-Carotene, lycopene, lutein, zeaxanthin, and beta-cryptoxanthin.
"This is one of the first studies to examine the bioaccessibility of carotenoids from fruits," said O'Connell.
They report that the transfer of carotenoids to the micelles was greater from fruits rather than vegetables, and that the xanthophyll carotenoids (lutein, zeaxanthin, and beta-cryptoxanthin) had high bioaccessibilities from fruits, ranging from 50 to 100 per cent.
While the bioaccessibility of lutein form fruit was also high (100 to 109 per cent), bioaccessibility from dark green vegetables like spinach and broccoli was significantlt lower (19 to38 per cent).
"The differences in bioaccessibility between the fruits and vegetables indicate that certain carotenoids are potentially more available from fruit for absorption by gastrointestinal cells," wrote the researchers.
The difference in bioaccessibility of the carotenoids from fruits and vegetables could be due to a number of different factors, suggested the researchers, including the effect of food constituents and the location of carotenoids in the food matrix.
"Fibre has previously been shown to have an impact on the absorption of carotenoids," they said.
"Vegetables are typically more fibrous in structure, which may explain in part the difference in carotenoid bioaccessibility from fruits compared with vegetables."
"The model represents a means to investigate rapidly and systematically the numerous potential factors, compounds, or conditions that impact on carotenoid bioaccessibility," they concluded.
The model could offer industry an inexpensive, labour- and time-efficient method of measuring the potential impact on the consumer's nutritional status.
According to Euromonitor International, the fortified and functional packaged foods market was worth €7.9bn at retail in the 14 biggest Western European markets.
Source: Nutrition Research (Elsevier) May 2007, Volume 27, Issue 5, Pages 258-264 "Xanthophyll carotenoids are more bioaccessible from fruits than dark green vegetables"
Authors: O.F. O'Connell, L. Ryan and N.M. O'Brien
