My research interest over the past few years focused on increasing the amount of evidence exploring the link between sugar consumption and disease development (particularly cardiovascular disease) in the context of nutritional recommendations. Therefore, as part of my doctoral thesis, I have conducted four studies on sugar consumption, with different factors connected to disease development in a large sample of the adult Swedish population.
For years, many nutritional recommendations for sugar intake used the risk of causing micronutrient dilution as a basis for their advice. Micronutrient dilution is characterised by a decreased consumption of nutrient-dense foods (like fruits and vegetables) due to an increased consumption of energy-dense foods (like processed snacks and sodas), which are high in fats and sugars and low in vitamins and minerals. My first study confirmed that the higher the intake of added sugars in the participants, the more likely they were to have a low intake of vitamins and minerals. Found in two independent samples of Swedish adults, these results pointed towards the continued existence of micronutrient dilution for over two decades.
Cardiovascular disease remains one of the greatest causes of disease and mortality worldwide. Therefore, understanding the dietary risk factors for cardiovascular outcomes is important in order to establish nutritional recommendations. Many cardiovascular diseases evolve from a phenomenon called atherosclerosis. Atherosclerosis is a process by which fatty materials accumulate on the walls of the arteries reducing their diameter, which decreases blood flow to organs. This accumulation can also form plaques that can dislodge and cause other pathologies.
My second study, investigated the association between several forms of sugar consumption and a marker of atherosclerosis called intima media thickness. This marker measures the thickness of the wall of the carotid arteries and can predict the possibility of developing cardiovascular diseases later on in life. However, this study could not find any conclusive link between sugar consumption and intima media thickness. While participants with a higher sugar consumption tended to have thicker artery walls, this finding would need to be studied further to confirm an association.
One of the most dangerous presentations of cardiovascular disease is stroke. Stroke is defined as a loss of brain function due to lack of sufficient blood flow. This lack of flow can occur if there is bleeding (haemorrhagic stroke) or if the blood vessels are blocked (ischaemic stroke). Stroke, like many other cardiovascular diseases, can be influenced by modifiable lifestyle factors, such as diet. My third study, analysed the risk of developing stroke within the context of dietary patterns considered healthy. Two healthy dietary patterns were chosen for such effect: following the Swedish dietary guidelines, and following a Mediterranean-style diet. In this study, a protective effect against stroke was found for individuals who better followed the recommendations of either of these healthy dietary patterns. For sugar in particular, a protective effect against stroke (particularly for ischaemic) was found in individuals consuming less than 200ml of soda per day, as recommended by the Mediterranean diet. Interestingly, a protective effect against stroke was also found for individuals consuming more than the three servings of sweets and pastries per week that the Mediterranean diet recommended. This contradictory finding could be explained by two possible scenarios. First, the deep-rooted Swedish tradition of fika (a break from activity where a hot beverage is consumed usually accompanied by a pastry). Fika breaks are not necessarily associated to an overall unhealthy diet or other unhealthy behaviours. Plus, the social element involved in this tradition has also proven to have beneficial health effects. Second, the fact that sugars in liquid form (like sodas) have a much more acute effect on our body than those consumed in solid form (like sweets and pastries).
Lately, scientists around the world have started to point towards the need for individualised advice when it comes to nutrition. As a result, the study of genetic markers in nutritional research has been on the rise to help understand the inherent differences between individuals. The first step towards understanding these disparities is to identify genetic variants that can be traced to the intake of specific foods or nutrients. In my fourth study, the association between genetic factors and sugar consumption was investigated. A connection was found between a genetic region in chromosome 19, linked to the fibroblast growth factor 21 gene, and the intake of sugar. This particular gene is known to code a hormone that has been previously linked to both intake and preference for sweet foods.
Informing nutritional recommendations on a regional, national, or international level is just the tip of the iceberg. Evidence-based dietary guidelines are usually the stepping stone for advising public health policies and strategies aiming to improve the health of millions. All in all, it seems that the study of sugar consumption still presents us more questions than answers. Solving our sugar-coated environment requires a multidisciplinary approach much more complex than what I could have covered during my time as a doctoral student. However, we should not stop wondering: should we have our cake, or should we eat it?
Although my doctoral thesis has been able to establish links between sugar consumption and both micronutrient dilution and genetic factors, the connection between sugar intake and more complex conditions, like cardiovascular disease, grants further study. While the overall scientific evidence is still inconclusive in its details, we should nonetheless aim to follow this simple advice: eat less sugar, you are sweet enough already.
Learn more!
I will be defending my PhD project “Sugar-Coated: the role of sugar intake and cardiovascular disease development in the context of nutritional recommendations” the next 21st of April 2022 at 13:30. This is a public defence seminar, so all are welcome! Join us at Agardhsalen, Clinical Research Centre (Jan Waldenströms gata 35), Malmö or on Zoom (Meeting ID: 628 4387 4127). You can also access the book and published papers here.