Avocado, its nutritional 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.

NUTRITIONAL VALUES
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.

POTENTIAL HEALTH BENEFITS OF AVOCADO
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.

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.The common dose of the Avocado-soybean unsaponifiables (ASU) in some of the studies is from 300 to 600 mg/day.

AVOCADO MAY HAVE BENEFITS OF CUTTING CANCER RISKS
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.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.

AVOCADO HELPS CHOLESTEROL-LOWERING DIETS
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.

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.

EFFECTS OF AVOCADO ON WEIGHT LOSS AND BLOOD PRESSURE
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.

BIOLOGICAL EFFECTS / SIDE EFFECTS OF AVOCADO ETRACTS AND OILS

One common side effect of avocado intake is allergy or hypersensitivity. The symptoms include skin reactions, vomiting, bronchial asthma, rhinoconjunctivitis, urticaria and angioedema.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.

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.

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.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.

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.

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. Six of 21 goats feeding on fresh avocado leaves from pruned trees, showed clinical signs of cardiac distress.Ingestion of avocado leaves also caused lung oedema, hydrothorax, severe myocardial degeneration, necrosis and fibrosis in 15 Cameroon goats. 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.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.