A researcher from the University of the Free State (UFS) is studying the influence of high fructose – a type of sugar naturally found in fruits, honey, and some vegetables – on memory and learning impairments and related metabolic/ systematic changes during different developmental stages.

Zinhle Priscilla Mvelase, a lecturer in the Department of Basic Medical Sciences, in the UFS Faculty of Health Sciences, is undertaking this research as part of her studies towards a doctoral degree in medical science (human physiology).

According to her, studies have documented that high fructose intake can lead to brain insulin resistance, which can potentially result in diminished cognitive function by altering the brain insulin signalling pathway. “The insulin signalling in the brain is involved in cognitive functions such as learning and memory. Moreover, a chronic high-fructose diet diminishes the brain’s ability to learn and remember information,” says Mvelase. 

Fructose consumption

People consume fructose by eating fruits, honey, drinking fruit juices, and ingesting processed foods and beverages that contain added sugars such as high-fructose corn syrup, which is commonly found in sodas, candies, and sweetened snacks. Though current scientific evidence does not support the need to completely avoid fructose-containing foods, but rather to consume them in moderation (≤50g/day), the current study is expected to yield compelling insights into the appropriate levels of fructose intake concerning memory and learning, kidney function, along with various metabolic parameters.

“Consuming fructose in the long run may cause renal (kidney) injury, glomerulosclerosis and diabetic microangiopathy. However, the exact mechanism through which fructose results in these complications is poorly understood.

“The paucity of scientific information on the effects of fructose on the kidney remains a concern. Therefore, scientific studies are needed to determine if limiting fructose may benefit subjects with kidney disease,” says Mvelase.

According to her, virous medicines were developed for treating memory deficit conditions, including drugs such as acetylcholinesterase inhibitors, rivastigmine and the NMDA-antagonist memantine. These drugs, however, have been shown to inhibit the deterioration process for a while. For example, they slow down the deterioration of the thinking and memory functions, such as language and arithmetic problems and orientation. Moreover, these drugs come with adverse effects such as nausea, diarrhoea and fatigue. As a result, alternative methods for treating memory and learning complications are therefore needed.

Quercetin-3-O-rutinoside (QUE), commonly referred to as rutin, shows promise as a potential therapeutic agent for mitigating the adverse effects of high fructose on brain insulin signalling. Further research is needed to fully elucidate its mechanism(s) of action.

“The present research aims to explore whether supplementation with Quercetin-3-O-rutinoside could potentially reverse the memory and learning impairments and alterations in the hippocampal insulin signalling pathway of offspring exposed to a high fructose diet during prenatal development,” Mvelase explains. 

The impact of the research

The study could help the researchers to better understand the relationship between high fructose intake and cognitive function, particularly memory and learning. It will also have an important impact for public health policies and dietary guidelines in South Africa, where high fructose corn syrup is commonly used as a sweetener in many processed foods and beverages. It could identify specific developmental stages during which exposure to high fructose may be particularly harmful to cognitive function, which could inform targeted interventions and preventative measures.

“Motivated by the stark literature highlighting the detrimental effects of high fructose consumption on various aspects of health, I recognised the urgent need for targeted research in this area,” Mvelase says. 

The NRF Thuthuka Grant

The study is funded by the National Research Foundation (NRF) Thuthuka Grant for the years 2024 to 2026. Prof MV Mabandla and Dr Mluleki Luvuno, both from the University of KwaZulu-Natal, are her supervisor and co-supervisor respectively. 

“This marks a significant milestone for my research endeavours. As an aspiring researcher this achievement represents a remarkable opportunity to delve deeper into my chosen field, pushing the boundaries of knowledge and contributing to the advancement of science. With the support of the NRF Thuthuka Grant, I am empowered to pursue my research goals with heightened enthusiasm and dedication, knowing that we have the resources,” she says.