Even identical twins respond differently to food

The largest ongoing study of its kind finds that people’s responses to food vary depending on a wide variety of factors. The findings suggest that the future of nutrition lies in personalised dietary advice.

Despite repeated public awareness campaigns and official dietary recommendations, the obesity epidemic is a persistent problem across the globe, and obesity-related conditions such as metabolic syndrome are a growing concern. The lack of personalised dietary advice may partly be the reason for this. For instance, one study pointed out that giving specific weight loss tips and having an empathetic approach toward those trying to lose weight can be much more beneficial than simply telling someone to improve their diet.

Drawing from a large twin study, scientists have conducted a nutritional response study with applied machine learning algorithms to show that one size really doesn’t fit all when it comes to a person’s diet. In fact, the new study reveals that even identical twins respond differently to food. These findings are part of what is the largest ongoing scientific study of its kind, which researchers at King’s College London (KCL) in the United Kingdom and Massachusetts General Hospital in Boston have carried out.

Studying people’s responses to food

In the TwinsUK study, Prof. Tim Spector and team examined 14,000 identical and nonidentical twins in an effort to understand the causes of various chronic conditions and distinguish between what may be genetic or environmental triggers. Furthermore, Prof. Spector and colleagues expanded on the TwinsUK findings by examining the biological responses that 1,100 participants had to certain foods over a period of 14 days. Around 60% of these participants were twins. The researchers measured markers such as blood sugar levels, triglycerides, insulin resistance, levels of physical activity, and the health of their gut microbiome.

Identical twins respond differently to food

The results showed that people’s biological responses to the same meals varied widely. This was true regardless of whether the meals contained carbohydrates or fat. For instance, some people had spikes in blood sugar and insulin levels — both of which are implicated in weight gain and diabetes. Others showed spikes in triglycerides that lasted for hours after a meal. Some research has linked triglycerides with heart disease.

Importantly, genes did not fully explain these variations. In fact, less than 50% of the variation in blood sugar, less than 30% of the variation in insulin, and less than 20% of the variation in triglycerides were down to genes. Also, the scientists “found out that identical twins shared 37% of the bacteria in their gut — only slightly higher than the 35% shared between two unrelated individuals,” Despite having the same genes and exposure to similar environments, identical twins often had very different glucose responses to set meals, whether they were high in carbs, fibre, fat, or sugar.

Surprisingly, the research also revealed that the information on the foods’ nutritional labels — such as fat, protein, and carb content — accounted for less than 40% of the difference between people’s biological responses to foods with a similar calorie content. These results, the team explains, suggest that factors including individual differences in people’s metabolism, gut microbiome, schedules, meal timings, and physical activity levels are just as important as the nutritional content of the food.

A ‘shift’ in the world of nutrition

Prof. Spector suggests, “People are finally starting to reject the notion that if everyone just follows the general guidelines (five servings of vegetables, counting calories, reducing fat) they’ll be healthy forever.”

“There’s also a lack of clarity around the impact of food choices on health and disease, or the best nutritional plan that each individual should follow to optimise their health and control weight… “This means we have the power as individuals to change how we respond to food and to choose the food that is best for us as individuals.”

Extracts taken from Ana Sandoiu from https://www.medicalnewstoday.com