Identical twins Hugo and Ross Turner have submitted themselves to become a pair of human guinea pigs and investigate whether a vegan diet is healthier than eating meat and dairy.
The Turner brothers are typically seen adventuring around the world, but the pair have recently been using their credentials as genetically identical twins for the benefit of science. As part of a recent study at the Department of Twin Research & Genetic Epidemiology at King's College London, the twins followed two distinctly different diets for 12 weeks: Hugo ate strictly vegan food, while Ross continued to eat meat and dairy products.
"We wanted to use the model of identical twins, who are genetic clones, to test the effect of diet and exercise and how these individuals respond to different types of food," explains Professor Tim Spector, an epidemiologist at King’s who led the research, speaking in a video for BBC Reel.
The results were subtle, but significant. Compared to meat-eater Ross, vegan Hugo experienced a massive drop in cholesterol and a sharp increase in resistance to type 2 diabetes. Hugo said that he struggled with the vegan diet for the first few weeks, experiencing huge cravings for meat and cheese, but he eventually got used to it and claimed to feel more energetic.
Notably, the vegan diet was associated with a steadier blood sugar level and energy level, while the carnivorous diet resulted in harsher peaks and dips of energy. Interestingly, however, the vegan diet resulted in a severe reduction in gut bacteria diversity, while it remained stable during the meat and dairy diet. In theory, this means that vegan Hugo could potentially have been more susceptible to illnesses compared to Ross.
Larger-scale research has revealed some surprising insights into gut bacteria and how individuals respond to food. A 2019 study by the same team at King’s College London found that peoples’ responses to the same foods are unique, even between identical twins. Despite eating the same meals, some people have sharp increases in blood sugar and insulin, which are linked to weight gain and diabetes, while others have fat levels that linger in the bloodstream, raising the risk of developing heart disease.
The reason for this, the study argues, is likely down to the gut microbiome – the trillions of bacteria that inhabit the intestinal tract. Although genetics does play an important role in how we process food, the gut microbiome also has a profound effect by influencing how the food is broken down. Since the composition of the microbial colony varies from person to person, so do our responses to the same food.
"We find that, on average, most identical twins only share between 25 and 30 percent of their microbes with each other," explained Professor Spector. "We think this is why many of their metabolisms are different and why they react to food differently."