Posted 28 June 2011
|DNA determines all your physical characteristics such as the colour of your eyes, hair and skin. Two strands of DNA are coiled together inside cells. These two strands contain 46 chromosomes and the result is the human genome – or a unique set of genes that make up each individual. But can we take samples of your DNA, select a sample of the genes and work out a special diet which would help you lose weight? |
Wow, would that not be wonderful!
The short answer is no, or at least, not yet.
However a “DNA diet” has been constructed and marketed on this very basis. Is there enough evidence that the selection of genes accurately predicts whether a diet constructed around the results works? I argued to the ASA that although there is good science behind the assessment of genes, at present few genes are definitive markers of specific diseases. In other words, many genes linked to specific conditions or diseases are never expressed (do not actually cause that disease) for they require other genes to be “linked” or depend on environmental conditions. In other words, you may have a positive gene but it has not resulted in the associated condition/disease from developing.
In this ASA ruling, the individuals behind the DNA diet (Dr. Daniel Meyersfeld and Yael Joffe) give what may appear to be a “convincing” argument in favour of the DNA diet. In this instance, the ASA ruled against the claims because the evidence presented in favour of the DNA diet, did not come from an “independent credible expert”.
This is exactly the point: “experts” may argue that their own science or results are absolutely correct – but do other experts support their conclusions or is this a minority opinion? Has results (or science) of specifically the “DNA diet” been published in peer-reviewed journals?
Indeed, this is exactly the point. There is no peer-reviewed articles to support the “DNA diet”. In spite of Meyersfeld and Joffe’s arguments, the majority of articles published to date in peer-reviewed journals do NOT support weight-loss diets constructed from DNA analysis. I have previously pointed this out.
Although this article was published in 2009, it does sum up perfectly the current status of DNA diets.
“Body weight excess has an increasingly high prevalence in the world. Obesity is a complex disease of multifactorial origin with a polygenic condition affected by environmental factors. Weight loss is a primary strategy to treat obesity and its morbidities. Weight changes through life depend on the interaction of environmental, behavioral and genetic factors. Interindividual variation of weight loss in response to different types of interventions (behavioral, caloric restriction, exercise, drug or surgery) has been observed. In this article, currently available data on the role of candidate gene polymorphisms in weight loss are reviewed. Even though control of weight loss by genotype was described in twin and family studies, it is premature to recommend use of genotyping in the design of therapeutic diets or drug treatment. Future studies will have to be large in order to assess the effects of multiple polymorphisms, and will have to control factors other than diet.”
Genetic variants influencing effectiveness of weight loss strategies.
Deram S, Villares SM. Arq Bras Endocrinol Metabol. 2009 Mar;53(2):129-38
This is further elaborated upon by another peer-reviewed article which concludes:
“Each individual possesses potentially hundreds of ‘at-risk’ gene variants and consumes a highly-complex diet. In order for nutrigenetics to become a useful public health tool, there is a great need to use mathematical and bioinformatic tools to develop strategies to examine the combined impact of multiple gene variants on a range of health outcomes and establish how these associations can be modified using combined dietary strategies.”
Rimbach G, Minihane AM. Nutrigenetics and personalised nutrition: how far have we progressed and are we likely to get there? Proc Nutr Soc. 2009 May;68(2):162-72.
DNA Diet / HA Steinman / 17153
Ruling of the : ASA Directorate
In the matter between:
Dr Harris Steinman Complainant(s)/Appellant(s)
Dnalysis (Pty) Ltd Respondent
27 Jun 2011
Mr Steinman lodged a consumer complaint against an advertisement that was featured in the Sunday Times Lifestyle magazine.
The advertisement features the lower body of a woman and the accompanying wording states, inter alia, “WITH SCIENCE, DIETING ISN’T A FAD.*”
The body copy states,
“Introducing one of the first products of its kind in the world, where science and nutrition meet, to create a scientifically proven diet and exercise plan; the DNA DIET.
Genetics plays a significant role in an individual’s ability to lose weight and their responsiveness to different diets. DNA DIET analyses 7 genes that impact metabolism and fat loss. These gene-based results provide personalised dietary changes, an eating plan to achieve optimal weight loss, and guidance as to the type and amount of exercise required, removing the guess work involved in choosing the best eating plan for you.
Order your DNA DIET test kit by visiting us on www.dnadiet.co.za, or book an appointment with one of our accredited dieticians.”
In essence, the complainant submitted that claims made are misleading and require substantiation. He added that there is no evidence that the diet is scientifically proven and that an exercise plan can be designed accordingly to an individual’s DNA. Furthermore, that there is not a single study evaluating whether the DNA diet is beneficial in constructing an effective diet.
Concerns were also raised about the range of applicability of DNA markers to the population at large. The argument appears to be that some DNA markers may only apply to a minority of people, yet the advertising implies that this test and its results can be applied to the entire population with positive effects. There is no proof of this.
RELEVANT CLAUSES OF THE CODE OF ADVERTISING PRACTICE
In light of the complaint the following clauses of the Code were taken into account:
• Section II, Clause 4.1 – Substantiation
• Section II, Clause 4.2.1 – Misleading claims
The respondent submitted that when developing a genetic test, gene variations are chosen to a well-established set of criteria (Kornman et al . 2004). One of these criteria is that the gene variation being analysed must be prevalent in the local population.
All gene variants analysed in the DNA Diet test have been shown in multiple studies to be both highly prevalent across disparate populations, and to play the same role in he aetiology of obesity and weight loss in all population groups studied. An analysis of genetic results of approximately 600 South African customers that have taken the DNA Diet test shows that the frequencies of these gene variants in the local population mirror almost precisely the expected frequencies found in population databases. A table illustrating this was also submitted. There is no basis to assume that the function of these genes would be any different to that shown in multiple populations and ethnic groups throughout the rest of the world.
All of the gene variants analysed in DNA Diet are highly prevalent in the local population. It is important to note that every individual will have one of two possible versions of the gene variant.
The DNA Diet genetic test consists of 7 genes (8 gene variations). Each gene plays a specific role in weight management and in an individual’s response to dietary and exercise interventions. It included a document listing a number of peer reviewed journal articles which allegedly show the role of the gene and gene variation in weight management and how it interacts with diet and exercise. A confidential document dealing with the specific effect of the 8 gene variations, and the relevant implications on diet was also submitted.
It is internationally recognised that the grouping of validated genes into a single panel is acceptable scientific practise, and it is not necessary to validate entire panels of genes independently. The DNA diet follows on from the development of a similar test in the United States.
The DNA diet is not a diet in itself, it is a genetic test that recommends dietary guidelines based on the unique genetic variants identified. The eating plans are developed by dieticians working in clinical practice in South Africa, thus the decision to make specific dietary recommendations to an individual can now be informed to a certain extent by knowledge of that person’s genetic make up for effective weight management.
All marketing efforts are created with dieticians in mind and the strongest endorsement comes from the dieticians themselves, who have been using the DNA Diet for up to 10 months.
It added that it offered to discuss the scientific validity behind its test with the complainant who declined such a meeting. The co-developer of the DNA Diet test has worked in the field of nutrigenomics for more than a decade and has co-authored a book on this subject matter, and worked with various international experts in this and related fields.
ASA DIRECTORATE RULING
The ASA Directorate considered all the relevant documentation submitted by the respective parties.
The Directorate’s first concern is whether or not the claims made are substantiated within the meaning of Clause 4.1 of Section II of the Code.
The overall impression created by the advertisement is that the respondent has a scientific approach, and can isolate certain genetic factors for each individual tested that impact on metabolism and weight loss. These results are then allegedly used to develop a personalised diet and exercise programme which is presumably guaranteed to work, given its specific application to the person tested.
Clearly these are claims capable of objective substantiation.
This clause 4.1 of Section II states, inter alia, that advertisers shall hold documentary evidence to support all claims that are capable of objective substantiation. It further requires that such documentary evidence shall emanate from, or be evaluated by a person or entity which is independent, credible, and an expert in the particular field to which the claims relate and be acceptable to the ASA.
It is trite that the ASA requires product-specific substantiation, and cannot extrapolate scientific jargon and literature in a manner that enables it to make a meaningful extrapolation as to whether or not the science verifies the claims for the advertised product.
The respondent submitted information relating to genotype frequencies which compares the South African population to the relevant population databases. It also submitted confidential documentation pertaining to information regarding metabolism, diet and exercise and the effect certain genes have on a person’s susceptibility to achieving success in relation to these factors.
The Directorate, however, is not a scientific body and is therefore not in a position to interpret scientific information. Hence, it required the respondent to furnish it with a report emanating from an independent, credible, expert in the field to confirm and verify the exact claims made in its advertisement for this particular product.
There is nothing in the respondent’s submissions to verify that its test can pinpoint such genetic factors in the manner claimed, and apply these findings in such a personalised and specific manner to enable guaranteed weight loss, due to the personalised diet and exercise plan resulting from ones DNA, or genetic predisposition. In addition, the respondent did not submit any information as to why the Directorate should accept that any of the documentation submitted emanated from, or was evaluated and confirmed by an independent, credible, expert in the relevant field.
Accordingly, the claims in the advertisement are currently unsubstantiated and in breach of Clause 4.1 of Section II of the Code.
Given the above finding:
The advertisement must be withdrawn;
The process to withdraw the advertisement must be actioned with immediate effect upon receipt of ruling;
The withdrawal of the advertisement must be completed within the deadlines stipulated by Clause 15.3 of the Procedural Guide; and
The advertisement may not be used again in its current format in future.
Given the above, it is not necessary to consider the remaining clause at this time.
The complaint is upheld.