March 5, 2009
Can your genes tell you how to eat?
The GenoType Diet claims that by eating according to one's gene group, one can boost certain genes and suppress others to improve the body's health and facilitate weight loss. WONG MEI LING reports
It doesn't get more faddish than in Hollywood and diets are no exception.
From singer-actress Jessica Simpson's Five Factor Diet to R&B icon Beyonce Knowles' Juice Fast, new dieting regimes have made news in the tabloids.
The latest to hit Tinseltown is the GenoType Diet, which America's highest-paid TV presenter, Oprah Winfrey, is a huge fan of.
It is created by American naturopathic physician Peter D'Adamo, author of The GenoType Diet, and is an expansion of the blood-type diet. Naturopathic medicine is an alternative medicine which claims that the body can heal and maintain itself naturally.
The Genotype Diet claims that 70 per cent of our genes are changeable as they are heavily influenced by environmental factors, dietary habits being one of the most influential.
The diet claims that depending on one's genetic group, or genotype, different problems and factors affect weight and metabolism.
Therefore, by eating according to one's genotype, one can boost certain genes and suppress others, which, in turn, can improve the body's health and facilitate weight loss.
It adds that there are six genotype groups: Hunters, Gatherers, Teachers, Explorers, Nomads, and Warriors.
A person's genotype group can be assessed by blood type, thumbprint, certain body measurements and various personality traits (see Food and your genotype).
Depending on the group type, the person's body requires different types of food and drinks. What may be harmful to one group can be beneficial to another.
For example, those in the Explorer group should eat organic red meat and poultry, while the Warrior group is advised to keep off red meats and poultry and eat oily ocean fish.
The Teacher and Nomad groups can include coffee in their diet, but the Explorer group is told to avoid it.
'Some of the diet's guidelines are quite sensible, for example, changing to monounsaturated and unsaturated fats and oils,' said Ms Karen Wright, lead dietitian at the Food Clinic in Leyden Hill, Bukit Timah.
Monounsaturated fats - found in foods like olives, nuts, canola oil and avocados - can lower cholesterol and may assist in reducing heart disease. It also provides essential fatty acids for healthy skin and the development of body cells.
However, Ms Wright noted that some of the recommendations do not specify the number of times that a food should be eaten on a weekly basis.
For example, Hunters are recommended to eat oily fish like salmon and sardines. However, she said mainstream health experts recommend that girls, and women planning to have a baby, consume oily fish no more than twice a week. This is because oily fish can contain residues of pollutants which can build up in their bodies over the years and affect reproductive functions later in life.
All other women, boys and men, should consume no more than four servings per week. This is because these fish may contain high levels of mercury.
Some dietitians here also question the scientific basis for the diet.
'No two persons, except identical twins, have the same genetic make-up just because they have the same blood type, body type or features,' senior dietitian and managing director of The Nutrition Place, Ms Pauline Chan, said. It is therefore misleading to claim that people of the same genotype, as defined by Dr D'Adamo, should eat or avoid certain foods, she said.
Both dietitians also point to the lack of scientific evidence to support Dr D'Adamo's genotype theory.
'There is no scientific evidence presented to back up his claims. The other source of information is from
Dr D'Adamo's own collection of data. However, again, no specific journals or studies are referenced,' Ms Wright noted.
So little is known about this diet that hospital-based dietitians in Singapore declined to comment on it, while major bookstores in Singapore like MPH and Borders do not carry books on the diet.
Ultimately, dietitians said, a balanced diet is essential for health. Diet fads do not lead to healthy and sustained weight management in the long-run, they added.
'The best way to lose weight is by eating fewer calories than are being used,'
Ms Wright said, adding that there is no one diet that suits all people in a particular category.
FOOD AND YOUR GENOTYPE
Hunters
Blood type: O; Personality type: detail-oriented and able to handle stress; Food type: red meat, ocean fish and basmati rice; avoid dairy products and coffee
Gatherers
Blood type: O or B; Personality type: focused, a problem-solver but tends towards emotional highs and lows; Food type: red meats, herring and sardine, rice and ginseng tea; avoid feta and mozzarella cheese
Teachers
Blood type: often A, occasionally AB; Personality type: calm and has close links with nature; Food type: mutton, white fish, coffee and green tea but keep chicken intake low; avoid white rice, wheat
Explorers
Blood type: A, B, AB and O; Personality type: quirky, entrepreneurial; Food type: red meat and poultry, oily ocean fish and basmati rice; avoid coffee
Warriors
Blood type: A or AB; Personality type: charismatic but occasionally bad-tempered; Food type: no red meats nor poultry; should eat oily ocean fish, brown rice, barley; drink coffee, black tea, red wine
Nomads
Blood type: B and AB; Personality type: easy-going and fun-loving; keeps emotions hidden; Food type: red meat and white fish; avoid rye and rye flour; beer, red wine and coffee are permissable.
Source: Dr Peter D'Adamo in the London Telegraph
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