Sugar has become one of the main “villains” of modern times: reducing it as much as possible from the diet is a priority goal if it is not naturally present in food. The World Health Organization recommends that consumption in the form of free sugars should not exceed 10% of total daily caloric intake, for both adults and children, and also suggests a reduction to below 5% of caloric intake (about 25 grams per day).
It depends on how we take them
These free sugars are sugars (refined or unrefined) added to foods and drinks by the manufacturer, cook or consumer, to which naturally occurring sugars in honey, syrups, fruit juices and juice concentrates must be added. The study of its consumption is therefore such a topical topic in recent years.
However, many investigations still neglect the form of ingestion—that is, whether they are free or self-contained—which could justify conflicting data between them. It is true that experts emphasize the importance of avoiding free sugars, but the lack of consideration in some studies may contribute to the discrepancy in the results.
Diana Thomas of the Center for Quantitative Obesity Research in New Jersey pointed out this omission. A situation that affects, for example, the glucose, cholesterol and triglyceride tolerance test: sometimes these parameters do not change, and sometimes they do.
Because of this lack of definition, guidelines have also been conflicting in recent decades, with sometimes recommending that sugar intake not exceed 5% of energy needs, while other recommendations suggest that even 25% of total energy can easily come. from the dietary component. A major enlightening study has yet to be submitted, but examining the issue through the lens of evolution may provide us with a clue to finding the truth.
Adapted to fresh fruit
Evolutionary physiology examines how organisms have changed over time to improve their fitness and survival. Their findings lead us to believe that evolution genetically adapted the metabolic physiology of our ancestors to deal with the internal sugar of fresh fruit because free sugar did not exist.
In the Miocene era, 24 to 5 million years ago, fruit was a major component of the hominid diet. According to Italian expert Riccardo Baschetti, four key findings bring an evolutionary perspective to the sugar debate:
- Stomach emptying and internal sugars. The speed with which food leaves the stomach is critical to blood sugar regulation as it passes through the intestines and is absorbed by the body. Glucose and native sucrose in food are excreted in a similar way.
- Evolutionary adaptation to fresh fruit. It is manifested by emptying, which slows down as the concentration of glucose increases. As has been shown, this phenomenon perfectly fits the caloric range of total sugars present in fresh fruit, which has been a staple of human nutrition for millions of years. Evolutionary adaptation suggests that our gastrointestinal system is designed to efficiently handle the wide range of calories from fruit and thus help maintain stable blood glucose levels.
- The effect of a large amount of fresh fruit. In the range of 0.2 to 1.0 kcal/ml, doubling the volume of the glucose meal was observed not to significantly alter the emptying rate. This means that eating large amounts of fresh fruit did not affect the homeostasis—the balance and internal stability—of glucose in our ancestors, and that human gastrointestinal physiology is adapted to efficiently handle large amounts of fresh fruit without negatively regulating glucose.
- Unknown free sugars. As the caloric concentration exceeds 1.0 kcal/ml, a faster delivery of calories to the small intestine is observed. This change occurs just above the highest caloric concentration in fresh fruit, suggesting that free sugars can be considered genetically unknown foods. The introduction of agriculture, about 10,000 years ago, is too recent on an evolutionary level for the human genome to have fully adapted to this change.
Another newcomer: salt
We must also take into account the role played by salt, the use of which our ancestors did not know until about 5000 years ago. Only since then have people started using it on a large scale to preserve food. However, our physiological systems did not have enough time to adapt to this increase in consumption.
Today we know that excess salt is harmful to health. But not only is it a risk factor for hypertension, it also speeds up the absorption of sugars in the gut, which could explain the link between sugary drinks and type 2 diabetes.
This relationship is due to the fact that the consumption of sweetened soft drinks tends to go hand in hand with a decrease in the intake of vegetables and milk, foods naturally low in salt, and a greater consumption of fast food and ultra-processed foods, rich in this spice.
The amount of salt present in ultra-processed foods contributes to the fact that a small portion inevitably passes through the consumption of sugary drinks, unhealthily accelerating the absorption of sugars and promoting obesity.
Some studies have actually shown that this link is mediated by dietary salt, but have neglected to mention the detrimental effect of this component on the absorption of sugars. These links provide us with valuable information on how our food choices can affect our overall health.
Notice to Scientific Mariners
We need to do a study that takes both sugar and salt into account, which would be consistent with evolutionary physiology and confirm what many already believe: that internal sugar is harmless and free sugar is harmful. As we said, Riccardo Baschetti has already set the tone for how to do this study. The only thing missing is that someone with a project without a conflict of interest can implement it.
Jose Miguel Soriano del Castillo, Professor of Nutrition and Bromatology in the Department of Preventive Medicine and Public Health, University of Valencia
This article was originally published on The Conversation. Read the original.
