Avocados Super-Enhanced Carotenoid AbsorptionOctober 2015
By Michael Downey
While most people think of avocado as simply the main ingredient in guacamole, it is certainly a superfood in its own right. The avocado is rich in monounsaturated fatty acids—including the powerful oleic acid also found in olive oil—and in fiber, folate, glutathione, phytosterols, flavonoids, and carotenoids, which are the pigments found in plants that contain a wealth of health benefits. In fact, this creamy, green fruit is packed with a host of different carotenoids, ranging from alpha-carotene to zeaxanthin, while also including lesser-known beneficial carotenoids such as neochrome.
Most importantly, the amount and combination of dietary fats found in avocado, as well as its abundant supply of oleic acid, provide optimal absorption of carotenoids—not just the carotenoids found in the avocado itself, but also the carotenoids found in other foods eaten at the same time.1
Exciting research indicates that the avocado’s rich content of carotenoids, fatty acids, and other nutrients promote joint, eye, and skin health and help prevent cancer, cardiovascular disease, metabolic syndrome, and obesity.
Rich Nutrient Content
An impressive 80% of avocado is dietary fiber, of which 70% is insoluble and 30% is soluble. The average serving is half an avocado, which provides a full 4.6 grams of fiber.2
Avocado is particularly abundant in oleic acid, a monounsaturated fatty acid that has been found to be the potent compound in olive oil responsible for its blood pressure-reducing effects.3
Critically, avocado also contains a high supply of other monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). The oil of avocado consists of 71% MUFA, 13% PUFA, and 16% saturated fatty acids—a profile that has been shown to help “promote healthy blood lipid profiles and enhance the bioavailability of fat-soluble vitamins and phytochemicals from the avocado or other fruits and vegetables, naturally low in fat, which are consumed with avocados.”2 It is not necessary to consume avocado oil to benefit from these potent fatty acids; researchers comparing avocado with avocado oil have found that the fruit matrix of the avocado pulp has no negative effect on lipid release.1
Also in high supply in avocado are the following:
- Phytosterols, including beta-sitosterol, stigmasterol, and campesterol,
- Non-carotenoid antioxidants, including the flavonoids epicatechin and epigallocatechin 3-0-gallate, vitamins C and E, and the minerals manganese, selenium, zinc, and boron,
- The omega-3 fatty acid, alpha-linolenic acid (about 160 mg per cup of sliced avocado),
- Polyhydroxylated fatty alcohols, and
- Glutathione, a tripeptide compound.
However, the greatest nutritional punch from avocado derives from its spectacular array of carotenoids, which scavenge free radicals and play an important role in eye health. Scientists believe that this carotenoid diversity is a key factor in avocado’s anti-inflammatory properties.4 When hearing of carotenoids, many people think of bright orange or red vegetables such as carrots or tomatoes. But the green pulp of avocado contains an assortment of carotenoids that includes:4
- Violaxanthin, and
In fact, the lutein content of the California Hass avocado (Persea americana Mill.) was found to be the highest among all commonly eaten fruits.5
Furthermore, carotenoid absorption from avocado is enhanced by its fatty acid profile. The high content of oleic acid is a crucial element of this enhancement. Within the digestive tract, oleic acid promotes the formation of chylomicrons, which are transport molecules that carry carotenoids up into the body.4
Boosts Carotenoid Absorption From Other Foods
This fortunate matchup between the fatty acid and carotenoid profiles in avocado even extends to the relationship between avocado and other foods. Scientists conducted a two-phase clinical study that demonstrated the powerful effects of adding avocado to other foods. There was a two-week washout period before each part of this crossover design.1
In one phase of this clinical study, either one cup (150 grams) of fresh avocado or 24 grams of avocado oil was added to a simple salad of romaine lettuce, spinach, and carrots that was consumed by the volunteers in one half of the crossover cycle, while the other half consumed avocado-free salads. In each case, the absorption of carotenoids was measured and compared nine-and-a-half hours after consumption. After eating the salad with added avocado, absorption of alpha-carotene increased 720%; absorption of beta-carotene increased 1,530%; and absorption of lutein increased 510%, compared to ingesting the avocado-free salad.
The addition of fresh avocado versus avocado oil made no difference to the carotenoid absorption-enhancement effect.1
Another phase of this study compared carotenoid absorption after consumption of salsa with and without the addition of either 150 grams of fresh avocado or 24 grams of avocado oil. After consumption of the avocado-added salsa, absorption of lycopene and beta-carotene was 440 and 260% times the absorption of these carotenoids, respectively, from avocado-free salsa.1
Avocado Promotes Healthier Joints
The complementary effects of avocado’s nutrients—carotenoid abundance and variety, beneficial fatty acid content and profile, phytosterols, non-carotenoid antioxidants, omega-3 fats, and polyhydroxylated fatty alcohols—have an ability to inhibit unwanted inflammation that is unquestioned among health researchers. Avocado’s phytosterols (stigmasterol, campesterol, and beta-sitosterol) are believed to help prevent excess synthesis of pro-inflammatory PGE2 by the connective tissue. These effects help to explain avocado’s ability to help prevent osteoarthritis and rheumatoid arthritis.4
Cartilage defects are an early indicator of osteoarthritis, the most common of joint disorders. They develop when inflammation and oxidative stress trigger cartilage deterioration.
Scientists reporting in Arthritis Research and Therapy found that consumption of fruits and vegetables rich in lutein and zeaxanthin—two key carotenoids in avocado—are associated with decreased risk of cartilage defects.6
In other studies, certain avocado extracts known as unsaponifiables have been shown to improve osteoarthritis pain and overall disability in people with hip or knee osteoarthritis, and may provide preventive effects when taken in the earliest stages of osteoarthritis.7-10
Avocado is high in the mineral boron. Research indicates that, in addition to preserving bone health, boron may help relieve the debilitating symptoms of osteoarthritis.11 There appears to be an important role for boron in promoting healthy joint structure and function.12
As you might expect, any fruit packed with the carotenoids lutein and zeaxanthin is bound to promote eye health.
Researchers found that women who had higher intakes of lutein and zeaxanthin had a 23% reduced risk of nuclear cataracts than women with lower levels. Also, lutein supplements given during a 12-week trial showed significant improvement in visual performance.13
In other research, diets rich in monounsaturated fatty acid—found in avocado—were shown to be protective of age-related eye dysfunction.2
Avocado’s Cancer-Blocking Ability
According to researchers, the same lutein and zeaxanthin content that enables avocado to protect eye health also inhibits Helicobacter pylori—a bacterium associated with development of stomach cancer.13
Higher intakes of glutathione—found abundantly in avocado—have been associated with a decreased risk of oral cancer. This anticancer effect is believed to derive from glutathione’s ability to neutralize oxidants and bind with cellular mutagens. Surprisingly, this reduction in oral cancer risk was only observed when the glutathione was derived from fruit or vegetables commonly consumed raw, as is usually the case with avocado.14
An acetone extract of avocado, containing carotenoids and tocopherols, was found to inhibit, in vitro, the growth of both androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines. Also, scientists suggested that the monounsaturated fat-boosted absorption of avocado’s carotenoids into the blood stream is likely to combine with other diet-derived phytochemicals to contribute to the significant cancer risk reduction commonly associated with a diet high in fruits and vegetables.5
Scientists have shown that phytochemicals extracted from avocado selectively induce cell cycle arrest, inhibit growth, and trigger apoptosis in both precancerous and cancer cell lines. Several studies indicate that avocado-extracted phytochemicals promote proliferation of human lymphocyte cells and decrease chromosomal aberrations, such as chromosomal breaks.15
Avocado’s boron content also plays a role. Research shows boron can shrink prostate tumor size, lower PSA, and potentially help to prevent prostate cancer. Men who ingested the greatest amount of boron were found to be 64% less likely to develop prostate cancer compared to men who consumed the least amount of boron.16
Protection Against Cardiovascular Disease
Avocado is an excellent source of fiber and folate, both associated with cardiovascular system protection. Epidemiological and clinical studies suggest that fiber reduces levels of LDL cholesterol and that folate helps decrease high homocysteine levels, a well-known risk factor for heart disease. Also, the phytosterols in avocado are structurally similar to cholesterol and act in the intestine to inhibit cholesterol absorption.13
Monounsaturated fatty acids—found in extremely rich supply in avocado—have been shown to reduce total cholesterol levels. In one study in the American Journal of Clinical Nutrition, scientists compared the effects of an avocado-enriched diet high in monounsaturated fatty acids with a diet high in complex carbohydrates. After three weeks, the avocado diet lowered total cholesterol by 8.2%, while the complex carbohydrate diet decreased total cholesterol by only 4.9%. The avocado diet also decreased LDL cholesterol levels, while the complex carbohydrate diet did not.17
In a study published in 2015, a research team compared three diets: a low-fat diet (24% fat), and two moderate-fat diets ( 34%). The moderate-fat diets were almost identical except that one included an avocado per day while the other provided a similar amount of oleic acid from other sources such as olive oil. The low-fat diet reduced LDL cholesterol by 7.4 mg/dL, and the non-avocado moderate-fat diet reduced LDL by 8.3 mg/dL—but the avocado diet slashed LDL by 13.5 mg/dL.18
Metabolic Syndrome And Weight Maintenance
An epidemiological study found avocado consumption to be associated with improved overall diet quality, nutrient intake, and reduced risk of metabolic syndrome.19 Monounsaturated fatty acids—robustly found in avocado—have been linked to the maintenance of glycemic control among type II diabetic patients. Researchers found that avocado can provide preventive effects against both obesity and diabetes.20
Scientists have found that avocados have a medium-level of energy density (1.7 calories per gram) and a matrix of viscose water, dietary fiber, and fruit oil—both of which promote a feeling of fullness that may benefit overweight individuals.21
More remarkable, a key monounsaturated fat in avocado acts directly on the brain as a natural hunger suppressant. Oleic acid, when it reaches the small intestine, converts into oleoylethanolamide (OEA), a lipid compound that activates a brain area responsible for greater feelings of satiety. This compound modulates feeding, body weight, and lipidmetabolism.22,23
A randomized, single-blind crossover study of 26 healthy overweight adults that was published in Nutrition Journal demonstrated that, compared to a control meal, half of a Hass avocado eaten at lunch significantly reduced self-reported hunger and desire to eat and boosted satiety over the five-hour period after lunch.24
Slower Skin Aging
Internal health benefits aside, avocado may deliver skin beautifying effects. The concentration of carotenoids in the skin is directly linked to the level of fruit and vegetable consumption. Specifically, a higher intake of vegetables that are yellow or green—such as avocado—has been associated with significantly fewer skin wrinkles.2
The monounsaturated fatty acids abundant in avocado moisturize skin from the inside. Its vitamin E, carotenoid, and glutathione scavenge free radicals, which can prematurely age and wrinkle the skin. Preclinical studies suggest that avocado compounds, including its polyhydroxylated fatty alcohols, can protect skin health by promoting wound healing and inhibiting UV damage. Avocado’s highly bioavailable carotenoids lutein and zeaxanthin may help also protect the skin from damage from both UV and visible radiation.2
The avocado is rich in monounsaturated fatty acids, a diverse array of carotenoids, fiber, folate, glutathione, and phytosterols. Critically, the amount and combination of dietary fats in avocado provide optimal absorption of carotenoids—not just the carotenoids found in the avocado itself, but also the carotenoids found in other foods eaten at the same time. Research demonstrates that avocado’s unique nutrient profile promotes joint, eye, and skin health and helps prevent cancer, cardiovascular disease, metabolic syndrome, and obesity.
If you have any questions on the scientific content of this article, please call a Life Extension® Health Advisor at 1-866-864-3027.
- Unlu NZ, Bohn T, Clinton SK, Schwartz SJ. Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. J Nutr. 2005 Mar;135(3):431-6.
- Dreher ML, Davenport AJ. Hass avocado composition and potential health effects. Crit Rev Food Sci Nutr. 2013;53(7):738-50.
- Terés S, Barceló-Coblijn G, Benet M, et al. Oleic acid content is responsible for the reduction in blood pressure induced by olive oil. Proc Natl Acad Sci USA. 2008 Sept 16;105(37):13811-6.
- Available at: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=5. Accessed May 1, 2015.
- Lu QY, Arteaga JR, Zhang Q, Huerta S, Go VL, Heber D. Inhibition of prostate cancer cell growth by an avocado extract: role of lipid-soluble bioactive substances. J Nutr Biochem. 2005 Jan;16(1):23-30.
- Wang Y, Hodge AM, Wluka AE, et al. Effect of antioxidants on knee cartilage and bone in healthy, middle-aged subjects: a cross-sectional study. Arthritis Res Ther. 2007;9(4):R66.
- Available at: http://www.webmd.com/vitamins-supplements/ingredientmono-890-avocado.aspx?activeingredientid=890&activeingredientname=avocado. Accessed May 1, 2015.
- Dinubile NA. A potential role for avocado- and soybean-based nutritional supplements in the management of osteoarthritis: a review. Phys Sportsmed . 2010 Jun;38(2):71-81.
- Lippiello L, Nardo JV, Harlan R et al. Metabolic effects of avocado/soy unsaponifiables on articular chondrocytes. Evid Based Complement Alternat Med. 2008 Jun;5(2):191-7.
- Boileau C, Martel-Pelletier J, Caron J, et al. Protective effects of total fraction of avocado/soybean unsaponifiables on the structural changes in experimental dog osteoarthritis: inhibition of nitric oxide synthase and matrix metalloproteinase-1. Arthritis Res Ther. 2009;11(2):R41.
- Gaby AR. Natural treatments for osteoarthritis. Altern Med Rev. 1999 Oct;4(5):330-41.
- Helliwell TR, Kelly SA, Walsh HP, et al. Elemental analysis of femoral bone from patients with fractured neck of femur or osteoarthrosis. Bone. 1996 Feb;18(2):151-7.
- Available at: http://www.healwithfood.org/health-benefits/avocado-superfood.php#ixzz3XFOT64Yu. Accessed May 1, 2015.
- Flagg EW, Coates RJ, Jones DP, et al. Dietary glutathione intake and the risk of oral and pharyngeal cancer. Am J Epidemiol. 1994 Mar 1;139(5):453-65.
- Paul R, Kulkarni P, Ganesh N. Avocado fruit (Persea americana Mill) exhibits chemo-protective potentiality against cyclophosphamide induced genotoxicity in human lymphocyte culture. J Exp Ther Oncol. 2011;9(3):221-30.
- Zhang ZF, Winton MI, Rainey C, et al. Boron is associated with decreased risk of human prostate cancer. FASEB J. 15:A1089:2001.
- Colquhoun DM, Moores D, Somerset SM, Humphries JA. Comparison of the effects on lipoproteins and apolipoproteins of a diet high in monounsaturated fatty acids, enriched with avocado, and a high-carbohydrate diet. Am J Clin Nutr. 1992 Oct;56(4):671-7.
- Wang L, Bordi PL, Fleming JA, Hill AM, Kris-Etherton PM. Effect of a moderate fat diet with and without avocados on lipoprotein particle number, size and subclasses in overweight and obese adults: A randomized, controlled trial. J Am Heart Assoc. Jan 7: 2015;4:e001355.
- Fulgoni VL, Dreher M, Davenport AJ. Avocado consumption is associated with better diet quality and nutrient intake, and lower metabolic syndrome risk in US adults: results from the National Health and Nutrition Examination Survey (NHANES) 2001-2008. Nutr J. 2013;12:1.
- Devalaraja S, Jain S, Yadav H. Exotic fruits as therapeutic complements for diabetes, obesity and metabolic syndrome. Food Res Int. 2011 Aug 1;44(7):1856-65.
- Wien M, Haddad E, Sabate′ J. Effect of incorporating avocado in meals on satiety in healthy overweight adults. 2011. 11th European Nutrition Conference of the Federation of the European Nutrition Societies. October 27, 2011. Madrid, Spain.
- Lo Verme J, Gaetani S, Fu J, Oveisi F, Burton K, Piomelli D. Regulation of food intake by oleoylethanolamide. Cell Mol Life Sci. 2005 Mar;62(6):708-16.
- Available at: http://www.healwithfood.org/articles/avocados-natural-appetite-suppressant.php. Accessed May 1, 2015.
- Wien M, Haddad E, Oda K, Sabaté J. A randomized 3x3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults. Nutr J. 2013;12:155.
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