SPECIAL REPORT: DNA Diets- Making the Most of Your Metabolism

16 May 2016 --- The belief that genetics has a large part in determining how our body reacts to food is becoming more popular in the diet food market. NutritionInsight explores the world of nutrigenomics and nutrigenetics to find out if these personalized diets really work.

One diet definitely doesn't fit all. This is because our bodies process fats and carbohydrates (carbs) differently; even when we eat the same foods, some of us put on more weight than others. Therefore, people are looking to alternative diets to help with losing weight.

Although exercise also has its part to play, as recently as five years ago the main weight loss message was more simplistic, relating solely to calories in and calories out: if you eat more calories than you burn, then you will gain weight. 
However, there are different types of calories that we eat and burn. Because the human body relies on fast energy, simple carbohydrates such as sugar, white flour, pasta and bread, are burned first. Then, the body moves onto protein, and finally fat. 

There are certain foods and beverages that can help speed up the body’s metabolism naturally. Eating at certain times of the day, along with how many meals you eat and what snacks you choose, can also affect metabolism and help in losing weight. This has been the focus of precision nutrition programs. 

Alfredo Martínez, MD, PhD Predident of the International Society of Nutrigenetics / Nutrigenomics (ISNN) told NutritionInsight about changes in nutritional research focus in recent times: “Precision nutrition is the stronger global trend nowadays. This new concept of nutrition considers not only the personal inheritance, but also the cultural and family aspects, their lifestyle, the previous clinical history as well as likes and dislikes, hypersensitivity or intolerance to certain foods, regular physical activity, the perinatal nutrition and epigenetics, when designing dietary advice and matching the nutritional needs of each person.”

For the ideal diet, how many calories your particular body needs each day needs to be determined, as well as how many calories it can burn and how fast, and finally what type of calories suits the body the best. This is where genetics comes into play. 

DNA diets have been an eye opener in how gene variations can impact eating behavior, and enter the nature vs nurture debate. Dr Trevor Jarman, CEO of My-gene-diet, which was developed in Denmark by a team of scientists, nutritionists and personal trainers, explained further to NutritionInsight: “Small variations in the genes we inherit from our parents can have a massive impact on our eating habits and weight management. Testing for these variations not only helps explain why an individual may struggle with their weight, it can also indicate the type of diet which will suit them best. With some variations, saturated fats are particularly bad news and a diet higher in healthier, complex carbs works best. For other variations a higher carb diet may contribute towards the accumulation of abdominal fat so a diet higher in protein and healthy, essential fats is recommended.”

Nutrigenomics vs Nutrigenetics
Nutrigenomics, or nutritional genomics, is a new branch of ‘omics’ science. It is the study of the effects of foods and food constituents on gene expression (or how foods affect our genes, and how individual genetic differences can affect the way we respond to nutrients in the foods we eat). 

“Different types of nutrients such as vitamins, minerals amino acids, etc. are able to change the process of gene transcription, translation and post-translation and, therefore, gene expression and functions,” explained Martínez.

Nutrigenetics, however, focuses on the role specific foods have in activating genes that affect susceptibility to certain illnesses such as Alzheimer's Disease and cancer.

“Nutrigenetics is focused on how a particular genotype determines the body's response to different foods,” Martinez clarifies. “Both sciences, Nutrigenomics and Nutrigenetics, intend to understand the reciprocal influences between food intake and genetic make-up of each person.” 

Research
Nutrigenomic research focuses on identifying and understanding molecular-level interaction between nutrients and other dietary bioactives with the genome.

The world’s largest trial in nutrigenomics, Food4Me, involved 500 volunteers from Europe (as reported by NutritionInsight on 29 Feb 2016). All those receiving personalized advice were eating significantly healthier than those on a standard diet up to six months after the project completed. However, no difference was found between those in the group who looked at their DNA and those who didn’t. Principal investigator John Mathers, professor of Human Nutrition at Newcastle University, UK, argues that the personalized approach, regardless of DNA information, was the key to success: “If you ask me whether it’s worth including the DNA tests in nutritional practice, my answer is: we are not there yet,” he said.

Paolo Gasparini, professor of genetics at Burlo Garofolo Hospital in Italy, co-authored a study on 191 obese people and found that those using a DNA-matched diet lost 33 percent more weight than those who were assigned to a standard calorie-counting group. Although these are impressive results, Gasparini stresses that DNA tests may be useful only if they are part of a comprehensive, personalized nutritional program: "A diet based only on DNA is the equivalent of a horoscope," he cautions.

Business
With the rise in awareness, has there also been a change in the genetic nutrition companies in recent times? No, says Jarman, who tests for eleven variations in six genes, including the FTO gene (known to increase hunger and the desire for energy dense foods, making dieting especially difficult): “Three years ago we were almost ahead of our time. Such diets are growing in credibility now and are available in pharmacies. However, It’s a very complex business to understand. The main issue is to promote them to the general public – this is where nutritionists come in.”

DNAFit claims to be the first company to provide fitness and nutrition to the general public. Launched in 2013, they offer a bespoke diet plan for adults “to boost your mood, help you lose weight and make you feel fitter.” The experts behind the revolutionary test, which has been used on Olympic athletes, state that people can lose a third more weight on their personalized diet plans than by calorie counting alone.

So how do these diets work? First of all, the genetic profile must be understood by completing a special questionnaire and taking a cheek swab test using a DIY kit. After sending the results for analysis, advice on menu plans, dining out or ordering in, shopping at the store, and snack ideas are created to help with weight loss, based on genetic predispositions.
“We figure out what foods work for your body and which foods don’t. If you follow your DNA Diet you will not only start to see weight loss, but you will also experience an improvement in mood, as once you give your body what it really needs to work most efficiently, it sends a pleasure message to your brain that makes you feel full and sated,” according to US nutritionist Carolyn Katzin who set up Carolyn’s The DNA Diet.

The verdict
So do these diets work? Yes, according to Katzin: “It does work, but like all things in life, you have to work it too. Nothing comes without some effort, but the DNA Diet will work in amazing ways for you, if you give it your all.”  

DNA diets also predict susceptibility to digestive conditions such as coeliac disease [an adverse reaction to gluten protein found in grains such as wheat, barley and rye]; as well as low digestive enzyme problems. Another positive noted by users is that this individual diet tells you what you should eat, rather than what you should avoid.

Martínez, who is also Professor of Nutrition at the University of Navarra, told NutritionInsight: “The so-called DNA-based diets are promising, but further investigation is required to identify the genetic variants involved in specific dietary outcomes and characterize both the interactions between genes, and the interplay between genes and lifestyle factors, such as diet or physical activity.” 

Applying computer technology to the management of biological and genetic information is an important factor: “Actually, the development of ‘omics’ technologies and bioinformatic tools are paving the way for implementing DNA diets or genotype-based nutritional treatments,” Martinez concludes.

Does nature or nurture affect weight more? It is very important to know what affects us on the outside, because that is what can be changed most easily. What affects us on the inside is harder to change but still possible. 

The general conclusion is that it is a 50/50 split between nature versus nurture: “Fifty percent of whom we are, what we look like and how we behave is already predetermined through genetics and is in our nature; the other fifty percent is what affects us after we are born (nurture) and includes how we are brought up, what foods our family ate or had us eat when we were little. What surrounds us now that affects our weight and our lifestyle such as what we eat, when we eat, how much exercise we take, how much sleep we get (those who don’t get enough sleep along with those who get too much, tend to be overweight), and if we smoke or not, amongst other things,” concludes Katzin.

Although genetically tailored diets are gaining in popularity, the consensus is that more research is needed before claiming success.

by Kerina Tull