When it Comes to Food, One Size Doesn’t Fit All!
World’s largest scientific nutrition research project reveals even identical twins have different responses to food.
Presented at both the American Society of Nutrition and the American Diabetes Association conferences, the findings demonstrate that old-fashioned, one-size-fits-all dietary guidelines are too simplistic and that a personalised approach to nutrition is likely to provide better long-term health benefits.
The study was led by an international team of leading scientists, including researchers from King’s College London, Massachusetts General Hospital and nutritional science company ZOE, and results showed that individual responses to the same foods are unique, even between identical twins.
The researchers measured how blood levels of markers such as sugar, insulin and fat change in response to specific meals, along with data on activity, sleep, hunger and gut bacteria (microbiome) in thousands of participants in the US and UK, mostly pairs of twins.
The team is also announcing a major expansion of its work in collaboration with scientists at Stanford and Tufts Universities. The next phase will recruit more than a thousand volunteers across the US who want to understand their own personal responses to food and contribute to cutting-edge nutritional science by taking part at home.
This ground-breaking nutrition research project was born out of the Twins UK Study – a unique 25-year investigation of health and lifestyle in 14,000 twins led by Tim Spector, Scientific Founder of ZOE, Professor of Genetic Epidemiology at King’s College London and author of The Diet Myth.
The key research findings presented at the ASN and ADA are:
- 1,100 UK and US adults (60% twins) were studied for two weeks of regular blood sugar (glucose) monitoring of blood sugar, insulin, fat levels (triglycerides) and other blood markers in response to a combination of standardized and freely chosen meals.
- The results reveal a wide variation in blood responses to the same meals, whether they contained carbohydrates or fat.
- For example, some participants had rapid and prolonged increases in blood sugar and insulin, which are linked to weight gain and diabetes. Others had fat levels that peaked and lingered in the bloodstream hours after a meal, raising the risk of developing heart disease.
- This large variation is only partly explained by genetic factors (less than 50% for glucose, less than 30% for insulin and less than 20% for triglycerides) and there is only a weak correlation between an individual’s responses to fat and carbohydrates.
- Identical twins who share all their genes and most of their environment often had different responses to identical foods. The study also finds that identical twins shared just 37% of their gut microbes – only slightly higher than the 35% shared between two unrelated individuals.
- Surprisingly, the proportions of nutrients such as fat, proteins and carbohydrates listed on food labels explain less than 40% of the differences between individuals’ nutritional responses to meals with similar amounts of calories. There are also large differences in responses to the same meals depending on the time of day they are eaten.
- The results suggest that personal differences in metabolism due to factors such as the gut microbiome, meal timing and exercise are just as important as the nutritional composition of foods, supporting the idea that simple nutritional labelling is insufficient for assessing food.
- ZOE’s machine learning algorithm makes predictions about an individual’s personal nutritional response that is strongly correlated with real-life measurements, and will continue to improve as the company’s dataset grows.
Professor Spector said: “The sheer scale and detail of our scientific project is such that for the first time we can explore tremendously rich nutrition data at the level of an individual. Our results surprisingly show that we are all different in our response to such a basic input as food. It was a real shock to see that even identical twins have such different responses.”
Dr Andrew Chan, Professor of Medicine at Harvard Medical School and a Gastroenterologist at Massachusetts General Hospital said: “It is reassuring that our genetic makeup only partially explains how our bodies respond to food. This underscores that our metabolism is not fixed – we have the power to change it. One exciting avenue is to tailor our diets to the bacteria in our gut that helps us metabolise nutrients.”
“For the first time, we’re expanding large-scale nutritional research beyond blood sugar. These findings show that the responses to food of a number of key metabolic markers – including triglycerides, insulin and blood sugar – are highly individualized. No one has been able to combine data on this scale before,” added Dr Sarah Berry, Associate Professor in Nutritional Sciences at King’s College London and Scientific Advisor at Zoe.
About the research:
- Twins UK Study: Led by Professor Tim Spector at King’s College London, this study of 14,000 identical and non-identical twins produced over 700 publications over the course of 25 years, exploring the causes of a wide range of common diseases and health conditions. Studying twins allowed researchers to separate the impact of genes (nature) from the environment and lifestyle (nurture). See twinsUK.ac.uk for more information.
- PREDICT 1 Study: Data from the Twins UK study was expanded through the first nutritional response study, carried out in the UK and US as a collaboration between King’s College London, Massachusetts General Hospital, ZOE and scientists around the world. The study intensively measured biological responses to specific foods in 1,100 people over 14 days, measuring a wide range of markers, from blood glucose and fat to exercise levels and gut microbiome diversity. The study included a full supervised day in the hospital with regular blood draws and wearable devices to capture sleep and exercise. Individuals also logged their food intake, hunger, and medication in an app, in addition to other clinical investigations such as gut microbe analysis. Tim Spector, Dr Andrew Chan, and Dr Sarah Berry are co-investigators.
- PREDICT 2 Study: An expanded at-home version of PREDICT 1, PREDICT 2, which launches today, builds on the existing collaboration between King’s College London, Massachusetts General Hospital, ZOE and scientists around the world. In addition to Tim Spector, Andy Chan and Sarah Berry, Christopher Gardner, Professor of Medicine at Stanford University, and Jose Ordovas, Professor of Nutrition at Tufts University, have joined as additional co-investigators.