Should you take a DNA test before starting your next diet for best results? Doctors explain

Genomic testing analyses an individual's genetic data to provide insights into their nutritional needs, dietary preferences and potential health risks.

Genomic testing for nutrition offers personalised dietary insights by analysing genetic variants that influence metabolism, nutrient requirements and disease predispositions. In an interview with HT Lifestyle, Dr Jaydeep Palep, senior consultant, gastro-intestinal and bariatric surgeon, (robotic and laparoscopic) at PD Hinduja Hospital and MRC, Khar shared his take on genomic testing for diet planning.

Did you know your genes play a significant role in how you metabolise your food, what kind of food will suit your body, and what deficiencies you are prone to? (Shutterstock)

What are the key benefits?

He said, “Certain gene variants influence how your body metabolises fats, carbohydrates, and proteins. For example, someone may have a gene variant that causes poor carb processing.”

Dr Sandip Shah, joint managing director, Neuberg Diagnostic, explained, “We keep hearing 'I have tried multiple diet plans but none worked for me'. One of the reasons for this could be our genes. Genes play a significant role in how we metabolise our food, what kind of food will suit our body, and what deficiencies we are prone to. Every individual has a unique genetic makeup, due to which our nutrient requirements are different. Knowing our unique code through genetic testing helps us plan our diet better, along with exercise regimen.”

Current limitations

Asked how accurate are the current DNA tests in providing actionable dietary advice, and can they be trusted to guide diet plans for conditions like obesity or metabolic syndrome, he said, “Genes like FTO, MC4R, PPARG, APOA2, and TCF7L2 have already been identified and linked but currently explain only 8-10 percent of obesity in a random population sample. Certain genetically tailored diets have shown better adherence to a diet plan in individuals, but are not clinically proven thus far.”

According to Dr Shah, “The current DNA tests are based on Genome Wide Association Studies (GWAS) where scientists look at genetic makeup of 1000’s of individuals with a disease/trait and normal individuals. Data from both is compared to deduce markers (Single Nucleotide Polymorphisms-SNPs), which are more common in individuals with disease/trait than in those without it. For example: FTO gene is one of the extensively studied genes in GWAS. It plays an important role in regulating hunger and satiety. There are certain markers in a FTO gene which increase the risk of obesity. These individuals feel hungry sooner, tend to snack more, and are drawn to sugary and fatty food. They can benefit from healthy snack options, being mindful of the portion size, introducing more protein and fibre in their food, and regular exercise can help them in their weight management journey.”

Dr Palep added, “Food intolerances like lactose, gluten, etc., can be specifically linked to gene variants. Actionable genomics, e.g., in vitamin and mineral metabolism, folate–MTHFR gene, and vitamin D — GC gene are clearly proven linked. As of today, associations/bodies like AHA ( American Heart Association) and European Society of Human Genetics (ESHG) say that genetic testing shows promise but is not definitive for dietary planning in preventive care.”

Speaking about what role genomic testing plays in identifying predispositions to conditions that can be influenced by diet, such as diabetes or heart disease, Dr Shah said, “As they say, a stitch in time saves nine. Knowing your genetic predisposition for high cholesterol, obesity, inflammation, salt sensitivity, and vitamin deficiencies, which influence your risk for diabetes and heart disease, helps in making the necessary lifestyle and dietary changes to reduce the risk for metabolic diseases.”

Adopting a gluten-free diet might not be necessary for everyone. Per doctors, food intolerances like lactose, gluten, etc., can be specifically linked to gene variants. (Freepik)

Genomic testing vs traditional diagnostic methods

Does genomic testing for nutrition differ from traditional diagnostic approaches in providing dietary insights? According to Dr Shah, this approach differs from traditional diagnostic methods, which typically identify current health issues rather than predicting future risks.

He said: “Traditional diagnostic approaches determine your current state of the body. For example, vitamin B12 deficiency is usually diagnosed after experiencing fatigue and numbness in the hands and legs. A genetic test tells you whether you are predisposed to have vitamin B12 deficiency, as you might not absorb vitamin B12 well from plant sources. In these individuals, diets to include more animal sources rich in B12 / fortified foods/ vitamin supplements can be introduced to avoid the deficiency.”

Ethical considerations

So, what ethical considerations should people keep in mind when opting for genomic testing for diet-related purposes? “Since there are no concrete randomised clinical trials supporting the theory of genomic testing for diet-related purposes, these tests should be offered to individuals with their informed consent, keeping them aware of the lack of scientific evidence or data for their use in day-to-day diet and nutrition planning,” Dr Palep said.

According to Dr Shah, a few parameters to check before opting for genomic testing are: scientific validity of the test, and whether genetic data is stored securely. “Genetics is an important component in our health. However, your lifestyle- sleep/exercise/stress also plays a role in disease risk. A genetic test works like a health compass — guiding you toward smarter choices and a healthier, happier life,” he said.

Before opting for genomic testing, consult with healthcare providers to understand the benefits and limitations.

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.