Sugar-sweetened beverages cause “molecular addiction” in small intestine: Study

MUMBAI: You could be eating a balanced diet but if you regularly consume sugar-sweetened beverages (SSBs), chances are your small intestine could be processing and asking for more sugar at the cost of vital nutrients. And this is only one outcome.

As the consumption of SSBs rises in many parts of the world including India, a multi-institutional study led by the Advanced Research Unit on Metabolism, Development & Aging (ARUMDA) in the Tata Institute of Fundamental Research (TIFR) has shown that the small intestine, liver and muscles—the organs associated with diabetes and obesity—have distinct responses to chronic sucrose intake. The study was published in the Journal of Nutritional Biochemistry on March 21.

Previous studies have shown a strong correlation between sucrose overconsumption and the increased risk of developing insulin resistance, steatotic liver disease and other diseases in humans. The present three-year study investigated the impact of 10% sucrose on cellular, molecular and metabolic pathways in a tissue-organ specific manner, which is nearly impossible to address in humans.

“To tackle disease, it is important to know the underlying mechanisms that contribute to its entire manifestation in different organs,” said Ullas Kolthur-Seetharam of ARUMDA. “Although scientists know that every organ does not behave similarly when there is a pathological manifestation/disease, very few studies have looked at individual organs as part of the same study.”

The study is important because findings from the UN Public Division, Global Dietary Database and other global studies have indicated an alarming increase in the consumption of SSBs globally, including in India. “Whatever the socio-economic status and urban/rural background, the consumption of sugar-sweetened beverages has increased in India. Moreover, these and fizzy drinks have become more accessible and cheaper,” said Kolthur-Seetharam.

Studies so far have observed the effect of very high sucrose concentrations (which are rarely observed in humans), excess sucrose in feed rather than in water and have investigated the ill-effects of overconsumption of fructose. In contrast, the present study has used a preclinical mouse model that closely mimics human consumption patterns. Researchers, over three months, fed the mice with 10% sucrose water. Commonly consumed beverages contain 10-15% sucrose.

Sonawane said their study surprisingly threw up three unique signatures. “Essentially, the mechanisms that were implicated in the intestines were not the same as those in the liver and in the muscles,” he said.

The study discovered that the small intestine is a major contributor to systemic glucose imbalances when sugar levels go low or high. Researchers made a serendipitous discovery: that three months of sweetened sugar water rewired the intestine to absorb more and more of it, a phenomenon called “molecular addiction”. This addiction leads to disproportionate absorption of glucose over other nutrients such as amino acids and fats that are essential for growth and development.

In the liver, increased glucose absorption triggered systemic insulin resistance, which leads to metabolic imbalance and obesity. In skeletal muscles, dysfunction of the mitochondria—the powerhouse of cells—and reduced efficiency in utilising glucose further contribute to metabolic disorders.

The team said the study findings stress the urgent need for policies and awareness campaigns to reduce SSB consumption, particularly among vulnerable populations.

Dr Nihal Thomas, senior professor at Christian Medical College, Vellore, who was not involved in the study, said the findings held a very important public health message. “WHO has also recently recommended that children under two should not consume sugar to reduce the likelihood of chronic diseases in adult life. With these findings, even as adults, we should be extraordinarily careful about consuming sugary drinks.”

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What are SSBs?

The Centres for Disease Control and Prevention define SSBs as liquids sweetened with added sugars such as brown sugar, corn syrup, dextrose, honey, molasses, raw sugar and sucrose. Examples include regular soda (not sugar-free), fruit drinks, energy drinks, sweetened waters, and coffee and tea with added sugars.