Key Points:

As the sylph-like Gwyneth Paltrow blogs about her post-binge purge, detox kits are disappearing from the shelves of health shops.

But before you shell out, listen to the experts: the detox drugs don't work - at least, not in the way they promise.

Auckland dietitian Angela Berrill has clients who take detox supplements for the holiday season.

"They all come back saying they feel great," she said. "But the reason they're feeling great is they're on a healthier diet and incorporating exercise rather than the fact they've been taking the supplements."

Frank Caruso, spokesman for popular Australia-made Quick Cleanse detox kits, admitted people could get similar health benefits free by following the programme's strict, mostly vegan, diet using lemons and brown rice.

"They can, but humans don't. I ran a healthfood store for years. I would write out an exercise and diet programme for them and they'd never do it."

He claimed the herbs helped remove waste from the body and said constipated people, in particular, benefited from the naturally laxative herbs.

North Shore GP Peter Boot dismissed claims about supplements' cleansing powers as "a total sales gimmick".

"[They] do not assist in the body in any way in terms of ridding it of metabolic byproducts and waste materials. However, if a person pays good money for something, they're more likely to take it seriously and adhere to a programme."

Our livers and kidneys were "amazingly efficient" natural detoxifiers, he said.

To feel better in the long-term, the advice is boringly familiar: eat plenty of wholefoods, lay off the fat, sugar, salt and alcohol, and take regular exercise.

"Like anything you've got to stick with, the minute you start going back to your old ways - stopping exercise and returning to your takeaways and alcohol - then of course any of the good is going to be undone," said Berrill.

"It's about lifelong changes rather than a quick fix for two weeks and resorting back to what you were doing before."

There is evidence post-binge health kicks don't boost the body's natural detoxification. A 2007 study at Imperial College London compared the recovery of two groups of women who had partied at a rock festival.

One group gave up processed food, soft drinks, alcohol, salt, sugar, caffeine, wheat, red meat and dairy, and the others followed their normal diet. After seven days, toxicologists found no difference in their liver and kidney functions or vitamin levels.
A report last week from British research body Voice of Young Science dismissed the word "detox" as meaningless.

Researchers examined detox claims for products ranging from foot patches to hair straighteners, and found manufacturers could not provide reliable evidence or even a consistent definition of "detox".

Extreme detox diets can be dangerous. Last year, British woman Dawn Page received more than NZ$2.05m in an out-of-court settlement after a high-water, low-salt diet left her with epilepsy and a brain injury affecting her memory, concentration and ability to speak normally.

* Gwyneth Paltrow's detox blog at goop.com