Written by Tatjana Djakovic, Staff Writer. Studies illustrate how avocado or avocado oil added to salads increased the absorption of carotenoids, lycopene, alpha and β-carotene and lutein.
Dietary intake of carotenoid-rich fruits and vegetables has been associated with reduced risk of many diseases including multiple types of cancer, cardiovascular disease, macular degeneration and cataract formation. (1) Carotenoids are organic compounds found in plants that are a source of pigment, vitamin A, and antioxidants which protect cells from harmful particles known as free radicals. Carotenoids are a class of molecules which includes α-carotene, β-carotene, lutein and lycopene. Enhancing the absorption of carotenoids by the cells in the body increases the health-promoting benefits of the nutrient as well as decreasing risk of deficiency of vitamin A which is a serious problem in developing countries. (2) Lipids (fats) are thought to be an important factor for carotenoid absorption, but most of the carotenoid rich fruits and vegetables are low in lipids. (3)
The objective of a recent study was to assess whether addition of avocado fruit and oil as a fat source enhances carotenoid absorption in humans. Before the study, the subjects were instructed to avoid carotenoid-rich foods for 2 weeks as washout period. The crossover study consisted of 63 healthy subjects aged 21-42 years that were randomized to 11 subjects per study.
The purpose of study one was to determine if avocado products increased the absorption of carotenoids, lycopene and β-carotene. The control group (11 participants) in study one consumed 300g of salsa and 3 slices of fat-free bread, and the treatment group (11 participants) consumed the same meal in addition to 150mg of avocado fruit, equivalent to 24g of avocado oil.
The purpose of study two was to determine the absorption of carotenoids lutein, alpha-carotene and B-carotene. The control group (11 participants) in study two consumed a salad containing prepackaged ingredients of 100g carrots, 40 g lettuce, 80g baby spinach, 2 slices of fat-free bread and 40 g fat-free Italian salad dressing. The treatment group (30 participants) received the same meal in addition to 75g, 150g avocado, or 24g of avocado oil.
In study one, the addition of avocado to salsa enhanced lycopene and β-carotene absorption by 440% and 260%, respectively in comparison to control (p< 0.003). In study 2, the addition of 75g or 150g of avocado or 24g avocado oil resulted in 830%, 720% and 890% increases in the absorption of α-carotene, respectively. The absorption of B-carotene was increased by 1360% with consumption of 75 g avocado, 1530% increase with consumption of 150 g of avocado, and 1740% increase in absorption with intake of 24g avocado oil. Lastly, the absorption of lutein was increased by 430% with consumption of 75mg of lutein, 510% with consumption of 150g of lutein, and 670% with intake of 24g of avocado oil. These results were did not occur by chance alone (p<0.003).
A higher amount of avocado did not result in higher absorption of α-carotene, signifying a non-linear relationship between the amount of lipid ingested and absorption of carotenoids. The researchers are not clear as to the minimum amount of lipid required for optimal carotenoid absorption. It can also be seen that lutein absorption was not as significantly increased as the other carotenoids, which agrees with previous research which has shown that specific carotenoids may require different amounts of lipids for optimal absorption. (5)
The study suggests that addition of avocado (half or whole fruit, equivalent to 75 or 150g avocado, respectively) enhances carotenoid absorption to an extent similar to that of an equivalent amount of added oil. The absorption of carotenoids from salad was very low when consumed alone. The addition of lipids in form of avocado fruit or oil is suggested to provide a healthy way of helping the body absorb the nutrient.
Source: Unlu, Nuray Z., et al. “Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil.” The Journal of nutrition 135.3 (2005): 431-436.
© 2005 American Society for Nutritional Sciences
Posted January 29, 2013.
References:
- Johnson, E. J. The role of carotenoids in human health. Nutr. Clin. Care 2002. (5) 56-65.
- Mayne, S. T. Antioxidant nutrients and chronic disease: use of biomarkers of exposure and oxidative stress status in epidemiologic research. 2003. J Nutr. 133:933-940.
- Roodenburg, A. J., et al., Amount of fat in the diet affects bioavailability of lutein esters but not of alpha-carotene, beta-carotene, and vitamin E in humans. 2000. Am. J. Clin. Nutr.(71) 1187-1193.
- Unlu, Nuray Z., et al. “Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil.” The Journal of nutrition 135.3 (2005): 431-436.
- Roodenburg, et al., Amount of fat in the diet affects bioavailability of lutein esters but not of alpha-carotene, beta0carotene, and vitamin nE in humans. 2000. Am J Clin. Nutr.(71): 1187-1193.
