Avocados side effects, nutritional values and health benefits
Avocados were first cultivated in South America with later migration to Mexico. It was believed that a Mayan princess ate
the very first avocado and that it held mystical and magical powers. European sailors traveling to the New World used
avocados as their form of butter. Avocados were first seen in the United States in the early 1800's. California is currently
the largest producer of avocados stateside. There are more than 80 varieties, with the "Hass" variety dominating the
crop share. A single mature avocado tree can produce more than 400 pieces of fruit in a year.

Avocados are loaded with nutrients such as dietary fiber, vitamin B6, vitamin C, vitamin E, potassium, magnesium, and
folate. They're also cholesterol and sodium free. Avocados contain 60% more potassium per ounce than bananas. This
fruit is an excellent source of monounsaturated fat. In addition, researchers have shown that avocados extracts improved
calcium absorption in rats and addition of avocado to salsa significantly improved lycopene, lutein and carotenes
absorption in healthy human subjects. [1, 9]

Researchers from South Africa proposed to use Avocado (Persea americana) leaf aqueous extract for the management
of childhood convulsion. The data from their study in rats suggested that 'avocado' leaf aqueous extract produced its
anticonvulsant effect by enhancing GABAergic neurotransmission and/or action in the brain. [8]

Some studies show the potential benefits of soybean combined with avocado on the symptoms of osteoarthritis. [12-15,
18] The combo is believed to exert anti-inflammatory and stimulatory effects on aggrecan or proteoglycan synthesis in
chondrocytes. [15, 17] The common dose of the Avocado-soybean unsaponifiables (ASU)  in some of the studies is from
300 to 600 mg/day. [16, 19]

The California Hass avocado (Persea americana Mill.) avocados were found to contain the highest content of lutein
among commonly eaten fruits as well as measurable amounts of related carotenoids (zeaxanthin, alpha-carotene, and
beta-carotene). Lutein accounted for 70% of the measured carotenoids, and the avocado also contained significant
quantities of vitamin E. An acetone extract of avocado containing these carotenoids and tocopherols was shown to inhibit
the growth of both androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines in vitro.
[11] On the other hand, Kim OK from Kyoto University, Japan, proposed that persenone A, an active ingredient of
avocado, is a possible agent to prevent inflammation-associated diseases including cancer. They found that persenone
A at concentration of 20 microM almost completely suppressed both iNOS and COX-2 protein expression in a vitro study.

Researchers found that intake of avocado could enhance the effect of low-fat diets on lipid reduction. [22, 26] Mexican
researchers consider avocado as an excellent source of monounsaturated fatty acid in diets designed to avoid
hyperlipidemia without the undesirable effects of low-saturated fat diets on HDL-cholesterol and triacylglycerol
concentrations. [23]

In a study of healthy adult normolipidemic volunteers and 37 adult patients with mild hypercholesterolemia, Mexican
researchers found that intake of avocado was linked to a significant decrease of serum total cholesterol (17%),
LDL-cholesterol (22%) and triglycerides (22%), and increase of HDL-cholesterol (11%) levels in hypercholesterolemic
subjects. [24]

The consumption of 200 g/d of avocado within an energy-restricted diet does not compromise weight loss when
substituted for 30 g of mixed dietary fat. Serum lipid concentrations, plasma fibrinogen, arterial compliance, and systolic
and diastolic blood pressures were not affected by weight loss or avocado intake. [10]

One common side effect of avocado intake is allergy or hypersensitivity. The symptoms include skin reactions, vomiting,
bronchial asthma, rhinoconjunctivitis, urticaria and angioedema. [25, 28] In a study, eight of the 21 avocado skin test
positive patients reported that symptoms repeatedly followed the ingestion of avocado; two reported systemic reactions,
but six noted oral symptoms only. Serum IgE antibodies to avocado were elevated in seven of the eight patients
reporting symptoms after eating avocado. Avocado-induced symptoms occurred in 8% of 100 consecutive atopic allergic
rhinitis patients unselected for avocado reactivity. Oral, and less frequently systemic, allergy symptoms appear to be
more common among the atopic population than previously appreciated. [25]

In later 1980s, researchers from Israel fed rats with avocado or avocado seed oils for four weeks and they noticed an
increase in the amount of hepatic lipids, a decrease in blood levels of triglycerides in the animals and changes in levels
of some liver enzymes. [2]

Rats fed with unrefined avocado oils showed significant increases in soluble collagen content in skin. The increased
soluble collagen content appears to be a consequence of the inhibition of lysyl oxidase activity. The total collagen
content did not change. [4] However, researchers also found a significant decrease in total collagen solubility in the liver
after supplementation of unrefined avocado or soybean oil to rats for one week. They confirmed the results by repeating
the experiment with chicken. They also found collagen accumulation in the liver of the rats, suggesting early stages of
fibrosis. [5]

Though there are indications (above) that avocado may damage the liver by collagen formation, Japanese researchers
have shown the protective effects of avocado on liver injury caused by D-galactosamine. [20]

The leaves of avocado in doses exceeding 20 g fresh leaf per kg bodyweight, produced damage to the mammary gland
with decreased milk production in an animal study. [3] Six of 21 goats feeding on fresh avocado leaves from pruned
trees, showed clinical signs of cardiac distress. [6] Ingestion of avocado leaves also caused lung oedema, hydrothorax,
severe myocardial degeneration, necrosis and fibrosis in 15 Cameroon goats. [7] In a study, nine out of 120 ostriches
died from congestive heart failure within 96 h of ingesting avocado leaves and immature fruit in an avocado orchard
containing Hass and Fuerte cultivars.[27] Finally, researchers from Kenya observed dyspnoea, pulmonary oedema,
abdominal enlargement and signs of elevated liver enzymes from two dogs which had a fondness for avocado fruits. [29]


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