Eating avocado reduces damage from air pollution, heart attack
But scientists have found that extracts of the leaves, fruits, seeds and bark of avocado can protect the body from the damages of air pollution.
Botanically called Persea americana, avocado belongs to the plant family Lauraceae.
Indeed, scientists have found higher levels of vitamin E may help protect the lungs from particulates – tiny particles of harmful smog.
These particles come from a variety of sources, including power plants, factories, trucks and cars and the burning of wood. They can travel deep into the lungs and have been associated with increased numbers of hospital admissions for heart attacks and strokes.
A new study from King’s College London and Nottingham University, United Kingdom, suggests higher blood levels of vitamin E may minimise the effects of exposure.
The study is published in the American Journal of Respiratory and Critical Care Medicine.
Also, scientists suggest that extracts of the nutritious avocado fruit may be able to lessen the liver damage caused by the hepatitis viruses.
A study carried out at Shizuoka University in Japan and published in Journal of Agricultural and Food Chemistry suggests the avocado fruit may have potential. Rats were given a chemical, which causes similar liver damage to the hepatitis viruses, and fed 22 different types of fruit to see if they made any difference.
The researchers found five compounds extracted from fruit to have a beneficial effect, and the most potent of these came from the avocado.
The scientists are still not sure whether the same effect could be found in humans, and say further studies are needed. They also have no idea how the avocado extract actually has this effect.
Precisely how much help this would be to stem the damage caused by hepatitis in humans is as yet unclear, as often patients are wholly unaware of their infection until serious damage has taken place.
Healthy: A 100g serving of avocado provides 10 per cent of the recommended daily allowance of vitamin E, which may help protect the lungs from particulates.
Harmful: Smog over the Chinese capital Beijing. The particulate matter of which it is made is one of the main air pollutants thought to be damaging to human health.
Vitamin E is important because it acts as an antioxidant to fight free radicals, the dangerous naturally occurring oxygen molecules blamed for various diseases.
Because it protects cell membranes, vitamin E maintains healthy skin, eyes and strengthens the immune system, according to British National Health Service (NHS) Choices.
The advice website says men need 4mg of vitamin E a day, while women need 3mg, and you should be able to get all you need from your daily diet.
A 100g (3.5 ounce) serving of avocado provides 10 per cent of the recommended daily allowance of vitamin E – likewise a serving of cooked spinach.
Any vitamin E your body doesn’t need immediately can be stored for future use, so it doesn’t need to be consumed every day.
The Department of Health advises that taking 540mg or less a day of vitamin E supplements is unlikely to cause any harm. For the first time, researchers found a clear link between the amount of the vitamin in the body, exposure to particulate pollution and lung function.
They say there is now growing evidence that some vitamins may play a role in protecting the lungs from air pollution.
Particulate matter (PM) is one of the main air pollutants thought to be damaging to human health.
Dr. Ana Valdes, Reader at Nottingham University and co-author of the study, said: “Our work builds on a number of studies exploring whether some vitamins can counteract the negative effect on lungs caused by air pollution.
“More work is needed to establish whether antioxidant supplements do indeed provide protection to the lungs in the general population.”
The new study looked at links between lung function, a set of metabolites – chemical signatures circulating in the blood – and exposure to two types of particulate matter, PM10 and PM2.5
The study involved 5,500 people from the UK twins registry who had also undergone tests to measure lung capacity and function. Around 500 twins living in the Greater London area also had their long-term exposure to PM estimated from their postcode.
Participants completed a medical history and lifestyle questionnaire, including questions on whether they took vitamin supplements, according to a report published in the American Journal of Respiratory and Critical Care Medicine.
The study revealed 13 metabolites significantly associated with the lung function scores. Of the metabolites associated with lung function, eight were also significantly associated with exposure to both types of particulates, PM2.5 and PM10.
Among the eight metabolites identified were alpha tocopherol, a biologically active form of vitamin E, and a metabolite of vitamin C.
Volunteers with a higher exposure to PM2.5 had significantly lower levels of alpha-tocopherol and also had lower lung function.
The findings provide further evidence that particulate matter may damage lungs through oxidative attack – by producing damaging chemicals – while vitamin E acts to minimise oxidative injury.
Co-author Professor Frank Kelly, Head of the Environmental Research Group at King’s College London, said “These new findings are consistent with previous reports which observed lower levels of vitamin E in people with lung conditions such as asthma.
“However, we do not yet fully understand which types of particulate pollution specifically damage the lungs or which vitamins best interfere with this pathway to reduce the level of damage.”
Previous studies have shown that the medicinal relevance of the various parts of this tropical plant is enormous. The effects of aqueous seed extracts of avocado on the blood pressure, plasma, and tissue lipids of albino rats were investigated by Imafidon and Amaechina, and their results suggested that the use of the aqueous seed extract of this plant in the treatment of hypertension might produce a favourable lipid profile.
Alhassan and colleagues also evaluated the hypoglycaemic activity of avocado aqueous seed extracts on alloxan-induced diabetic rats and concluded that the anti-diabetic effects of the extract might be due to certain mineral elements and phytochemicals and that an increase in weight could be due to proper nutrient utilisation that is most likely induced by the avocado seed extract.
However, the work by Okonta et al. suggests that avocado can lower blood glucose levels in cases of mild hyperglycemia but not severe hyperglycemia.
Edem et al. studied the effects of aqueous alligator pear seed extracts on normal and alloxan-induced diabetic rats, and their results suggested a restorative (protective) effect of the extract on pancreatic islet cells.
The work of Mahadeva et al., concentrated on the mechanism of the anti-diabetic activity of avocado. The insulin-stimulative and antioxidative effects of avocado were evaluated in streptozotocin (STZ)-treated rats.
This group found that the activities of pathophysiological enzymes such as serum aspartate transaminase (AST), serum alanine transaminase (ALT), and serum alkaline phosphatase (ALP) were altered in the serum of rats that had been treated with glyclazide, which was used as the standard reference drug, but not control rats. These results revealed the tissue-protective nature of avocado fruits.
The aforementioned studies provided further insight into the restorative and antioxidant activities of avocado.
However, the tissue-protective potential of avocado necessitated a look into the histopathological activity of the plant extract in the pancreas, liver and kidneys.
The study published in Malaysian Journal Medicine and Science concluded: “In summary, the plant extract exerted a dose-dependent protective effect on the pancreas, kidneys and liver, like the reference drug glibenclamide did. Taken together, the results of present study provide a pharmacological basis for the folkloric use of the hot-water extract of Persea americana seeds in the management of diabetes mellitus.”
Yet another study on the effect of liquid extract of avocado leaf on plasma levels of aminotransferases, cholesterol and total bile acids in hypertensive patients by researchers from the Achievers University, Owo, Ondo State, found that raw liquid extract of Avocado pear leaf is of medicinal importance in the treatment of hypertension.
The study published recently in American Journal of Medicine and Medical Sciences reads: “In Oke-Ogun area of Oyo state, this extract is being used as an alternative therapy in the treatment of hypertension in human subjects. Fifty anicteric newly diagnosed hypertensive patients with an abnormal increase in plasma cholesterol and blood pressure aged 45 and above that have not been treated with any hypertensive medication but have decided to be treated traditionally using avocado pear leaf extract were recruited from the traditional homes in ATISBO, Saki-East and Saki-West Local government areas of Oke-Ogun – the Northern part of Oyo state-Nigeria.