Featured article in the Summer 2015 Issue of Nutrition Close-Up; written by Jung Eun Kim, PhD, RD and Wayne W. Campbell, PhD
The 2010 Dietary Guidelines for Americans emphasizes consumption of 4.5 cups of fruits and vegetables daily. However, the average intake of fruits and vegetables in U.S. adults is only 2.6 cups.1 This low consumption of fruits and vegetables may result in the limited availability of fat soluble, health-promoting phytochemicals such as carotenoids from these foods. Dietary carotenoids have biological properties, including antioxidant and anti-inflammatory effects, which may help protect against certain chronic diseases, including cardiovascular diseases, age-related macular degeneration, and some types of cancer.2 The bioavailability of carotenoids from a meal can be affected by several factors, such as food matrix, type of food processing, nutritional status, interactions with other dietary compounds during digestion and absorption, and gut status.3 However, co-consumption of carotenoid-rich foods with dietary lipids may be one of the most effective stimulators of the absorption of carotenoids.4
Eggs contain highly bioavailable carotenoids, specifically lutein and zeaxanthin. The dietary lipid and phospholipids in egg yolk are known to enhance the intestinal absorption of these carotenoids. The highly bioavailable nature of carotenoids from eggs suggest that the dietary lipid and phospholipids contained in egg yolk may also help increase the bioavailability of carotenoids found in co-consumed fruits and vegetables. While promising, very limited data exist on the impact of co-consuming whole egg with carotenoid-rich foods and whether overall carotenoid absorption may increase via lipid rich egg yolk.
Recent research conducted with 16 healthy young males showed that the absorption of carotenoids contained in a carotenoid-rich meal was effectively enhanced by co-consuming cooked whole eggs.5 Subjects consumed a raw mixed-vegetable salad including tomatoes, shredded carrots, baby spinach, lettuce, and Chinese wolfberry as sources of carotenoids with no egg; with 1½ eggs of scrambled whole egg; and with 3 eggs of scrambled whole egg (randomized, crossover design). The total carotenoids and total lipid contents in raw mixed-vegetable salad with no egg, with 1½ eggs, and with 3 eggs were 23mg, 23.4mg (0.4mg from eggs), and 23.8mg (0.8mg eggs); and 3g, 10.5g (7.5g from eggs), and 18g (15g from eggs), respectively. The absorption of total and individual carotenoid, including lutein, zeaxanthin, α-carotene, β-carotene, and lycopene was 3 to 8-fold higher when the raw mixed-vegetable salad included 3 eggs compared to no eggs.
These results are consistent with previous findings that healthy young adults had approximately 12.5, 40, and 3-fold increases in post-prandial α-carotene, β-carotene, and lycopene absorption, respectively, when they consumed a salad with full-fat salad dressing (28g) versus fat-free salad dressing.6 Also, an acute feeding study designed to examine the impact of both amount and source of dietary lipid on the absorption of carotenoids from a mixed-vegetable salad showed that the amount of co-consumed lipid is a primary potentiator of carotenoid absorption rather than the source.7
Over the past 10 years, low-fat or fat-free versions of food products typically co-consumed with vegetables (e.g. salad dressings) are readily available.8 Recent studies strongly suggest that dietary lipid is necessary to absorb those fat soluble, health-promoting phytochemicals, and co-consuming cooked whole eggs with carotenoid-rich foods such as raw mixed-vegetable salads is an effective dietary strategy to enhance the absorption of carotenoids. Also, this research highlights that eggs, a nutrient-rich food containing dietary protein, unsaturated fatty acids, and vitamins and minerals, may be used to enhance the nutritive value of other carotenoid-rich foods.
Jung Eun Kim, PhD, joined Purdue University’s research team in 2012 as post-doctoral research associate. She earned her PhD in Nutritional Science at the University of Connecticut in 2011; she coordinates current studies in Purdue’s Campbell Lab.
Wayne W. Campbell, PhD, is a professor at Purdue and lead investigator in the Department of Nutrition Science. Dr. Campbell earned his doctorate degree from Tufts University School of Nutrition, and received post doctorate training at The Pennsylvania State University.
- Recent studies strongly suggest that dietary lipid is necessary to absorb fat soluble, health-promoting phytochemicals.
- The highly bioavailable nature of carotenoids from eggs suggest that the dietary lipid and phospholipids contained in egg yolk may help increase the bioavailability of carotenoids found in co-consumed fruits and vegetables.
- The absorption of total and individual carotenoid, including lutein, zeaxanthin, α-carotene, β-carotene, and lycopene, was 3 to 8-fold higher when the raw mixed-vegetable salad included 3 eggs compared to no eggs.
- United States Department of Health and Human Services, U.S.D.A., and United States Dietary Guidelines Committee. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010.
- Krinsky NI, Johnson EJ. Carotenoid actions and their relation to health and disease. Mol Aspects Med. 2005;26(6):459-516.
- Yonekura L, Nagao A. Intestinal absorption of dietary carotenoids. Mol Nutr Food Res. 2007;51(1):107-15.
- Goltz SR, Ferruzzi MG. Chapter 6. Carotenoid Bioavailability: Influence of Dietary Lipid and Fiber. 2013. Internet: http://download.springer.com/static/pdf/600/chp%253A10.1007%252F978-1-62703-203-2_6.pdf?auth66=13637981504ee3ec14d79630924ec3a08a7aa944da&ext=.pdf (accessed 4 March 2013).
- Kim JE, Gordon SL, Ferruzzi MG, et al. Effects of egg consumption on carotenoid absorption from co-consumed, raw vegetables. Am J Clin Nutr. 2015. [Epub ahead of print].
- Brown MJ, Ferruzzi MG, Nguyen ML, et al. Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection. Am J Clin Nutr. 2004;80(2):396-403.
- Goltz SR, Campbell WW, Chitchumroonchokchai C, et al. Meal triacylglycerol profile modulates postprandial absorption of carotenoids in humans. Mol Nutr Food Res. 2012;56(6):866-77.
- Sandrou DK, Arvanitoyannis IS. Low-fat/calorie foods: current state and perspectives. Crit Rev Food Sci Nutr. 2000;40(5):427-47. Internet: https://www.endocrine.org/~/media/endosociety/Files/Meetings/PPTOX%20IV/53_Birnbaum.pdf. Accessed 2-28-15.