The alkaline diet, also referred to as the pH diet, is the latest eating plan to take the alternative health sector by storm and has been embraced by celebrities such as Kirsten Dunst, Anna Faris and self-help guru Anthony Robbins.

Pioneered by American health entrepreneur Robert O. Young, the diet operates on the idea that eating too many acid-forming foods, such as meat and dairy, puts stress on the body, leads to weight gain, exacerbates inflammation and can cause the condition acidosis.

The theory goes that we can ''alkalise'' our bodies by consuming a greater proportion of alkaline foods, such as green vegetables.

There are plenty of products on the market to help achieve this, from recipe books to chlorophyll supplements and alkalising water ionisers. But do we really need to alkalise our acid-washed bodies? Well, no, according to associate professor in nutrition and health education at the University of Sydney, Dr Jennifer O'Dea.

Blood pH is regulated to stay within the narrow range of 7.35 to 7.45, making it slightly alkaline. ''The acidity or alkalinity of the human body is maintained within very tight control by the stomach acid, gall bladder, liver and kidneys - any rise or fall in acidity or alkalinity is quickly managed,'' Dr O'Dea says.

''The idea that food can be acid or alkaline is irrelevant because the stomach acid regulates this.''

A dietitian with the Dietitians Association of Australia, Tania Ferraretto, described the alkaline diet as yet another fad that would not be sustainable in the long term.

''I don't support the supposed science behind this diet,'' she says.

''I can't think of any reason why you should eat alkaline foods and eliminate acidic foods. It will mean people miss out on essential nutrients such as calcium, iron and zinc, which are really important.

''Women are usually the targets of these sorts of diets and they tend to be low in calcium and iron anyway.

''It would be dangerous to try to do this diet long term because of those nutritional deficiencies.''

However, therapeutic chef Sam Gowing believes the alkaline diet might have some benefits. She says most people consume too much meat and not enough greens as it is and any increase in vegetable intake is a positive thing.

''If we eat too many acid-forming foods - that includes some grains, animal flesh, alcohol - we get a build-up of acid in the body and that will cause things like heartburn and indigestion, which places stress on the body,'' Gowing says.

''Ideally, our diet should be 80 per cent alkaline and 20 per cent acidic. But it's the opposite for most people.'' In Australia, the diet is promoted by the family of the late Melbourne chiropractor Annie Guillet, who followed the eating plan after being diagnosed with inflammatory breast cancer in 2009.

She used the principles established by Young, whose website claims he has ''devoted his life to researching the true cause of disease'' and for 25 years has been ''recognised as one of the top research scientists in the world''. What his site doesn't note is that he has been investigated by the US National Council Against Health Fraud as well as leading US consumer website quackwatch.com.

Striking a balance

ALKALINE FOODSAlfalfa, asparagus, almonds, brussels sprouts, broccoli, cabbage, cauliflower, celery, cucumber, garlic, lettuce, onion, peas, spinach, zucchini, carrot, potatoes, avocado, tomato, tofu and olive oil.

ACID FOODSBeef, chicken, eggs, ocean fish, organ meat, oysters, pork, veal, cream, hard cheese, homogenised milk, bread, butter, margarine, artificial sweeteners, chocolate, white sugar, beer, coffee, spirits and wine.

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