Four years after his book, The China Study, was published, author and research scientist Professor T. Colin Campbell still stirs up controversy over diet and disease.
The Jacob Gould Schurman Professor Emeritus of nutritional biochemistry at Cornell University, who was in Singapore last month to give a talk, did not mince his words.
Prof Campbell, 75, reiterated the key point in his 2005 bestseller - that diets high in animal protein are strongly linked to diseases like cancer and heart problems.
The book is available here at Books Kinokuniya at $29.89.
His recommendation? Our diet should be whole, plant-based food, not meat and dairy products.
He explained: 'We grow more rapidly with animal proteins, which are more efficient in replacing the proteins we need.
'They have the capacity to stimulate growth hormones. Protein is an essential nutrient but there are levels we require for growth. Beyond that, too much can lead to cancer.'
He suggested that we eat no more than 12 per cent of our daily dietary allowance of protein, which he insists should be plant protein.
One recent study over 10 years seems to back Prof Campbell's stand.
The report, in The Archives Of Internal Medicine in March, studied more than 500,000 men and women in America aged between 50 and 71. It found that those who regularly ate red meat had a modestly higher risk of dying of cancer or heart disease than those who ate very little.
However, some nutritionists here do not see eye to eye with his views.
Ms Pauline Chan, a senior dietitian and managing director of The Nutrition Place, said: 'Every food has its role in diet. Meat, especially lean ones, and fish are important sources of high quality protein that are important for keeping us healthy.
'Diet plays an important role in health and disease but it is not accurate to state that all meat, including fish, can lead to cancer.
'In fact, there are many factors that can affect an individual's risk of cancer and they are not necessarily related to meat intake. Risk factors include one's genetic make-up, lifestyle choices like smoking and health conditions such as obesity.'
Madam Koay Saw Lan, the head of dietetics and nutrition services at Singapore General Hospital, said a good approach to daily nutrition is to include food from all five food groups of the healthy diet pyramid, food in the right serving portion and food that is easily available and fits one's lifestyle and budget.
She said: 'Eating right and healthy need not be complicated. Neither does a single food or meal make or break a healthful diet.'
Clearly, Prof Campbell is urging people to turn vegetarian. But do so slowly, he advised.
'Many people just quit meat and milk immediately. My family and I did it gradually as I was learning things gradually. It took us five to 10 years before we totally switched to whole, plant-based food,' he said.
Indeed, he cautioned that going full-tilt into healthy eating can be overwhelming and stressful, even leading to disorders like orthorexia.
This is an obsession with healthy eating - it occurs when eating healthy food so dominates a person that he is affected in a physical, emotional or social context.
Dr Lee Huei Yen, a consultant at the department of psychiatry at Singapore General Hospital, said she has seen only a few orthorexic cases here, some involving vegetarians or raw vegans.
She added: 'Current health information is mostly targeted at confronting the upward trend in obesity, with a never-ending barrage of healthy eating messages in the media by health experts.
'This tends to give out a message that unwittingly encourages orthorexia. There are probably other factors involved, like a patient's underlying personality type.'
Treatment for orthorexia includes counselling, getting patients to try different foods again and medication.
Besides meat and milk, the professor took a potshot at health supplements and popular diets like the low-carbohydrate Atkins Diet.
He said: 'Health supplements are industry-driven. They make money by pushing people to buy their products. What studies have shown is that they have no effect on our health.'
Indeed, last December, two long-term studies from the National Institutes of Health in the United States found that vitamin supplements do not help fight cancer or prevent ailments like stroke and heart disease.
A review of nearly 70 studies on the effects of vitamin or antioxidant supplements, published in The Cochrane Library in April last year, concluded there is no evidence that these prolong life.
Dr Christian Gluud - the director of medical science, associate professor and department head of the Copenhagen Trial Unit at the Centre for Clinical Intervention Research and Copenhagen University Hospital in Denmark - and his colleagues even warned that healthy people who take supplements such as vitamins A and E could be throwing their body's natural defences off track and increasing their risk of early death by as much as 16 per cent.
Prof Campbell said people should not 'obsess' about supplements or some new diet.
'Just eat whole, plant-based food and make sure you get a good variety of such foods,' he said.
