Posted 13 April 2010
The claims are based on one study only – a study by Nelson et al* and not published or peer reviewed but presented at a congress. Those wishing to make money from this expensive blood test reference this test as proof that the diet works and has been proven.
What was the concluding point made by Nelson and colleagues? They are quoted as saying: “The researchers said their findings were preliminary, and need much more confirmation before they could be used commercially“. http://news.bbc.co.uk/2/hi/health/8550091.stm
We feel the claims are premature . . .
The company claims that they have identified eight genes that will identify factors influencing weight-loss. In fact these genes were identified by other researchers and selected by these researchers as suitable markers. However, firstly, the company marketing the DNA have not proved in a peer-reviewed study that these genes are in fact effective in weight-loss in all individuals for epigenetics plays a role. Epigenetics is a term that points out that although one may have a gene for a specific disease or condition, that it may not result in that condition because of other factors in the background. For example, if you have a gene for a heart disease, but another factor is not playing a role, that you will never develop heart disease – you do need that special factor. This is a crucial factor for a gene that may be highly relevant in say, Japan, may be irrelevant in South Africa – it needs to be checked.
The company in their marketing also may suggest that these genes, or similar genes, were shown to result in weight-loss in an American study. Firstly, the study has not been published and reviewed by peers yet (was presented at a conference), secondly, the design of the study may be flawed (has not been published for scrutiny), and thirdly, in science when studies involve a small number of study subjects, then the findings need to be checked and reproduced in other studies.
This is the study that I am referring to:
* Mindy Dopler Nelson, Prakash Prabhakar, Venkateswarlu Kondragunta, Kenneth S Kornman, Christopher Gardner. Genetic Phenotypes Predict Weight Loss Success: The Right Diet Does Matter. (Oral Presentation #4). Presented at the American Heart Association’s Joint Conference – 50th Cardiovascular Disease Epidemiology and Prevention and Nutrition, Physical Activity and Metabolism – 2010, March 2-5, 2010, San Francisco, CA.
Mindy Dopler Nelson and Christopher Gardner represent Stanford University; all others represent Interleukin Genetics, Inc.
Read this sentence carefully:
“They found that those on a diet which matched their genotype lost 2-3 times more weight over 12 months compared with those on the “wrong” diet. The researchers said their findings were preliminary, and need much more confirmation before they could be used commercially. http://news.bbc.co.uk/2/hi/health/8550091.stm
In the Sunday Times Lifestyle magazine of 11 April 2010, Claire Keeton wrote a great balanced article on this test and its claims.
It is reproduced here:
The DNA Diet
Apr 11, 2010 12:03 AM | By Claire Keeton
With obesity on the rise and no magic bullet to losing weight, scientists are searching for answers in our genes. Claire Keeton reports on a new round of ‘fat wars’
EVER wondered why a friend faded away on the Atkins diet but his girlfriend didn’t lose even half as much weight?
The answer could be in their genes – maybe he drops kilos eating sirloin and nuts but her DNA mix is better suited to pasta with pesto.
The pioneers of a new diet in South Africa claim the days of “trial and error” dieting are over. But is the “DNA diet” simply the latest fad or does it have a scientific basis?
New research suggests that people can lose two to three times more weight on a diet matched to their genotype than if they are on an inappropriate diet. However, these results are from a small study among overweight women in the US.
Joburg dietician Anne Till says: “Genetically we have not changed in the past 100 or 200 years and obesity is escalating year on year. This is not attributed to genes but to how people live. Everyone is looking for the Holy Grail of dieting and a solution to their problems. What makes all the difference is how much you eat and how much you exercise.”
This holds true for the followers of any popular diet: Atkins, South Beach, SureSlim, Weight Watchers, Anne Till, X and Weighless. You name it. When the Sunday Times staff did their own experiments, dubbed the “Fat Wars”, into how well these diets work, one point was clear: you only get results if you stick to the plan. And most of the volunteers had more fun feasting and drinking than eating green vegetables.
But back to the latest offering. To follow the DNA diet you must have eight genes tested which influence metabolism and fat loss. The results will suggest whether a low-carb, a low-fat, low-GI (moderate carb, low fat) or healthy balanced diet will work best for you.
Dnalysis is the second company in the world to offer a DNA diet, according to its CEO, Dr Daniel Meyersfeld.
He says the company tested more than 100 people in the first week of operation last month. But it is too soon to know if they will have success in losing weight.
Meyersfeld, a molecular biologist, says the product is based on scientific research from the past 10 years. The DNA diet falls under an exciting new frontier in weight control known as nutrigenomics; that is, how genes and food interact.
He says: “The DNA diet is not a fad. We know people respond differently to low-carb and low-fat diets. The point is to skip the guesswork. Ten years ago nutrigenomics was out there scientifically and now it is in mainstream universities.”
However, South African dieticians and scientists are cautious about the potential of a DNA diet. They warn it is jumping the gun to offer a diet linked to the results of a few gene tests, when about 600 genes relate to metabolic functioning and obesity.
Celeste Naude, a researcher and dietician at Stellenbosch University’s division of human nutrition, says: “Analysing a few gene variants and ignoring other possible interactions within this vast genomic diversity may result in incomplete analyses and the possibility of misguided interventions.”
She said the scientific evidence was in its early developmental stages. “Any personalised – genetically based – dietary advice is premature.”
The president of the Association for Dietetics in South Africa, René Smalberger, says: “The field of genetic testing and the link between genetics and dietary prescriptions have been investigated for the past few years, with mixed results.
“I believe there is not enough conclusive evidence to prove the link between genetics and weight loss.”
Gene testing and products associated with their results are available in the US. Meyersfeld said Dnalsysis wanted to bring existing biotechnology to South Africa even though it was still in its early stages.
“Who decides when there is enough research? We are bringing in the best available test now and in a year’s time there may be 10 more genes worth testing.”
Meyersfeld says the DNA test results would allow people to attain the best health, based on small lifestyle changes. “We are looking at low penetrance genes. By themselves they do not cause disease or weight gain but in combination with poor lifestyle choices they can.”
Till says: “Low penetrance genes do not causes problems and don’t express themselves unless mixed with an unfavourable environment.”
She adds that there is no magic bullet to losing weight, and that DNA clues could reinforce the need for behaviour change to an individual who has a health risk. For instance, if a person finds out that they have an increased risk of high cholesterol, they should modify their diet.
Meyersfeld says that a person on a DNA diet may feel more motivated to stick to a diet designed on a case-by-case basis rather than a “one size fits all” diet.
“In the worst case we will have a person who does not respond well. We are not putting people onto medication or making drastic changes.”
The jury is still out on whether DNA diets will deliver results but the interest in nutrigenomics is gaining momentum.
How it works
You sign up for the DNA diet online, pay a fee and receive a DNA diet test kit. The kit has instructions and a sterile swab inside a tube.
Taking the swab is easy (I tested it). You just scrape around inside your cheek, then seal the swab stick back in the tube.
You sign a consent form, fill in a questionnaire and post the tube to the laboratory. Your DNA diet report will be ready in about 14 days.
The report has five parts and the key message is simple: Remember, your genes cannot change, but your diet and lifestyle can.
A summary, like this sample, gives you the results: “Your genetic make-up says you are more likely to follow a Carbsmart diet and a moderate intensity exercise programme compromising 15 met hours (which measure the intensity) of exercise per week. Your exercise potential is as a power athlete.”
Other experts concur:
Dr Kotze mentioned that on the 11th of March, the genetic community received notification of an article published by Nadja Popovich entitled “Genetically determined dieting? Maybe not yet”, which cautions that although the Stanford study may have improved scientific understanding of why some people react better to one diet than to another, we have as yet not reached the point where a single-focused genetic test of variations in three genes can provide one slimming solution for all.
“Dr Maritha Kotze, one of our leading researchers in the field of genetics at the University of Stellenbosch Medical School” quoted here.
According to Nanette Steinle, an Endocrinologist at the University of Maryland Medical School, it is still “far too early to start offering this type of test to the public”. (Popovich, 2010). It is only when a genetic test is performed and contextualised according to the medical history and lifestyle of the individual, that the result could be helpful to pinpoint the most appropriate slimming diet.
Quoted here .