Spector is a geneticist who has eaten the same food for lunch every day for ten years: a tuna sweet corn brown bread sandwich, plus a banana. Like most people, he thinks these foods are very healthy. But he found that his blood sugar and blood lipid levels always soared after such a lunch. Hyperglycemia and hyperlipidemia are both risk factors for diseases such as diabetes, cardiovascular disease and obesity.
Although the tuna sandwich may seem unhealthy for Spector, it may be very healthy for others. Other foods that are generally considered unhealthy, such as ice cream, are healthy or not from person to person. Scientists have discovered that there are high individual differences in the metabolic response of the human body to the same food. If diet is good for health, theoretically everyone’s recipes should be different.
Glycemic reaction varies from person to person
In 2014, an Israeli research team conducted a study to explore whether artificial sweeteners used to replace traditional sugars and help relieve obesity and diabetes can worsen the condition. They gave healthy volunteers saccharin (an artificial sweetener), and the results were unexpected: the blood sugar levels of volunteers after consuming saccharin showed high individual differences-some of them had a significant increase in blood sugar, and some had an increase in blood sugar. The degree is within the normal range, and some people hardly increase.
Researchers are puzzled by two points: one is that artificial sweeteners do not contain calories and theoretically do not cause blood sugar to rise; the other is that the degree of blood sugar spikes should not be so different among different individuals—— In theory, after eating the same amount of the same food, although there are differences between individuals, the level of blood sugar rise should be about the same.
“Honey of A, Arsenic of B”
The glycemic index (GI) can be used to explain the above two questions. Glycemic index is a measure of the effect of food on raising blood sugar. Foods with high glycemic index will be quickly digested and absorbed, leading to a sharp rise in blood sugar. In fact, it does not make much sense to study the effect of a certain food on the blood glucose level of different individuals, because it is impossible to draw a universal conclusion, and the glycemic index describes the average blood glucose increase level of different individuals after eating the same food. It is universal.
Scientists did such an experiment, using white bread to test the blood sugar fluctuations of healthy volunteers (white bread is generally considered unhealthy because of its high glycemic index, which is about 75). Scientists thought that white bread would have a significant effect on raising blood sugar. However, after some people ate white bread, their blood sugar would hardly increase, but some people would increase to the level of diabetes. But no matter how different the white bread caused the blood sugar level of different volunteers to rise, their average increased level tended to a value, that is, the glycemic index of white bread.
This phenomenon broke people’s consistent understanding of food. In other words, there is no “perfect” food, that is, no matter who eats it, blood sugar will not soar. Moreover, because different people may have completely different glycemic reactions to the same kind of food, then this kind of food can be described as “the first honey, the second arsenic.” Therefore, rather than evaluating whether a certain food is healthy, it is better to evaluate a person’s glycemic response to the food: if the blood sugar spikes after eating, the food is unhealthy for the person.
Different foods have different glycemic effects (increasing from left to right).
Microorganisms in the body have a big impact
In another study involving 800 volunteers, the researchers integrated various personal information of the volunteers, such as age, gender, living habits, and medical history, and calculated their height and body mass index and waist-to-hip ratio. Finally, a stool sample of each volunteer was collected to analyze the status of their intestinal microbes. Then, the researchers monitored the volunteers’ blood glucose levels during the week and recorded their meals during each meal (meal time and type and quantity of food, recorded more than 52,000 person-times), sleep status and daily activity patterns . The results are consistent with what the researchers expected: Even after these 800 volunteers ate the same food, there were still very large individual differences in their postprandial glucose levels. Subsequently, the researchers discovered that the factors most closely related to the human body’s glycemic response are the biological characteristics of the individual, especially the composition of the microorganisms in the body. This means that only a few biometric data are needed to customize a low-glycemic index diet for anyone.
In order to further prove this conclusion, the researchers recruited 26 volunteers who may suffer from prediabetes (that is, there is a glucose metabolism disorder, but did not meet the diagnostic criteria for type 2 diabetes), and each of them was individually customized according to their microbial composition. 2 sets of personalized diet, the first set will cause blood sugar to spike, the second set will not. One week later, the researchers found that the first set of diets made the volunteers’ glycemic response more intense, while the second set improved their glycemic response. It should be pointed out that, unlike the diet recommended for prediabetes patients (such as whole grains, etc.), the second set of diet also contains some foods that are generally considered “unhealthy” (such as chocolate and ice cream, etc.).
Tailor-made meal plan
Specter recently chaired a study of “individual responses to dietary ingredients”, which focused on the level of triglycerides (a type of fat) in the blood after meals. 1002 volunteers participated. The results showed that after eating the same food, their blood triglycerides all showed different levels of increase. The triglyceride levels of some volunteers did not rise much, some fell to a steady state soon after rising, and others continued to rise for up to several hours. In addition, in 1002 volunteers, there are 86 pairs of twins with the same genetic sequence, but each pair of twins also has a difference in food metabolism, which indicates that genes have little effect on food metabolism. Specter concluded from this that: the fluctuations of triglycerides and blood glucose levels after meals of different individuals have high individual differences, but the spikes in blood sugar and triglycerides do not occur simultaneously.
Before the start of the study, Spector measured the volunteers’ age, gender, height, weight, blood pressure, fasting metabolic level, biological rhythm, gene sequence, and microbes in the body, etc., and recorded their meal time and diet composition during the experiment. , Sleep and exercise. The above information can predict the individual’s metabolic response level to any kind of food. For specific metabolic indicators, the accuracy of triglycerides reaches 77%. Although the results are not accurate enough, it is far more reliable to formulate a meal plan based on this than to recommend “absolutely healthy” food to everyone.
Another study found that analyzing the metabolites in human urine can also infer its metabolic level. Therefore, it is foreseeable that in the near future, people only need to perform a few simple tests, such as blood and urine sample tests, and nutritionists can develop targeted meal plans for them.
However, do not go to extremes. We still need to generally follow the widely recognized guidelines for healthy eating, such as ensuring the diversity of diets, eating more fruits and vegetables rich in dietary fiber, properly intake of fats, and limiting the intake of refined foods. A personalized diet under such a major premise is a healthy diet suitable for everyone.