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Avocados Super-Enhanced Carotenoid Absorption

October 2015

By Michael Downey

Avocados Super-Enhanced Carotenoid Absorption

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

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

  • Alpha-carotene,
  • Beta-carotene,
  • Beta-cryptoxanthin,
  • Chrysanthemaxanthin,
  • Lutein,
  • Neochrome,
  • Neoxanthin,
  • Violaxanthin, and
  • Zeaxanthin.

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

The Healthiest Way To Peel And Eat Avocado
The Healthiest Way To Peel And Eat Avocado

If you want to get the maximum nutrition from avocados, ensure that you eat them very ripe and peel them correctly, using what is known as the nick-and-peel method. Research shows that the highest concentration of carotenoids in an avocado lies immediately below the peel.

So for optimum benefits from this super food, follow these steps:

Do not eat avocado when the outer peel is still green. If the peel on the avocado you bring home is green, do not refrigerate them. Store them at room temperature in a fruit basket or a brown paper bag until the peel has turned very dark greenish-black—but well before it begins to crack. If the avocado is ripe, the flesh will be definite green instead of a yellowish-green.

Once the peel has turned dark, it can be eaten right away or refrigerated for up to a week. If storing in the fridge, it is best to store avocados whole, because the green flesh quickly becomes oxidized when exposed to air and turns brown.

When eating a ripe avocado—with a greenish black peel—the best way to ensure that you do not lose the carotenoid-rich flesh just beneath the peel is to use what the California Avocado Commission calls the “nick-and-peel” method.

Rather than slice into the flesh with a knife, do this. Cut into the avocado lengthwise, producing two long avocado halves that are still connected in the middle by the seed or stone. Then, take hold of the avocado and twist the two halves in opposite directions and they should naturally separate. Pluck out the stone and cut each of the two halves lengthwise so that you now have four long sections.

Next, pick up one of the quarters and use your thumb and index finger to grip the very edge of the skin. You should be able to peel the skin off cleanly, as you would with a banana—leaving the carotenoid-rich flesh intact.

Store any unused quarters in the refrigerator wrapped in plastic bag. Sprinkling the exposed flesh with lemon juice or vinegar can help prevent the browning that can occur when the flesh comes in contact with oxygen in the air.

Properly ripened avocado flesh is creamy and spreadable. It is best eaten raw for full nutritional value. But if you do use avocado in a recipe that calls for heat, use the lowest possible temperature and the least amount of cooking time that will still work with your recipe—this will minimize damage to avocado’s unique fats. About 40 seconds of microwave heating on medium should not significantly change avocado’s fatty acid profile.

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

Vision Protection

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

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

Nutritional Content Of California Avocado

The avocado is rich in monounsaturated fatty acids—including the powerful oleic acid also found in olive oil—as well as fiber, folate, glutathione, phytosterols, antioxidant flavonoids, and carotenoids.

Hass avocados from California are the smaller, darker variety with bumpy green skin. They have a higher nutrient content than Florida avocados, which are larger, and have smoother skin and higher water content.

One cup (230 grams) of raw California avocado provides the following:25

Percent Daily Value

Calories

384

Calories from fat

297

Total carbohydrate

19.9 g

7%

Saturated fat

4.9 g

24%

Monounsaturated fat

22.5 g

Polyunsaturated fat

4.2 g

Omega-3 fatty acid

253 mg

Omega-6 fatty acid

3,886 mg

Cholesterol

0.0 g

0%

Dietary fiber

15.6 g

63%

Protein

4.5 g

9%

Sodium

18.4 mg

1%

Vitamin K

48.3 mcg

60%

Folate

205 mcg

51%

Pantothenic acid

3.4

34%

Vitamin B6

0.7 mg

33%

Vitamin E (alpha-tocopherol)

4.5 mg

23%

Boron

1,668 mcg

Potassium

1,166 mg

33%

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

Summary

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.

References

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