Nature conceals a phenomenal number of molecules as varied as they are imperceptible. The plant kingdom is particularly complex chemically.
Plant evolution has taken place over hundreds of millions of years, giving plants the ability to respond to various environmental stresses and threats. Several species have developed an arsenal of molecules allowing them to adapt and protect themselves against competitors and predators. Some of these molecules also have health benefits for the animals that consume them.
Advances in food science over the past few decades show that many plants provide a host of benefits that until recently were largely unknown. Together, these discoveries confirm more than ever the fact that a varied and balanced diet offers benefits that go beyond simple energy intake. As a result, consumer demand for plant-based foods with high nutritional value is currently at record highs. This trend has not yet run out of steam. At the same time, sugary foods are increasingly being marginalized and classified as unhealthy.
But in the kingdom of sweets, maple syrup finally takes its rightful place! Maple syrup is no longer just the crown jewel of Canada’s culinary heritage, its nutritional reputation is also improving. Due to its unique natural source and manufacturing process, maple syrup contains bioactive molecules whose benefits go far beyond the simple pleasure of a sweet treat.
Benefits that go beyond energy intake
In Eastern Canada, March and April herald maple sugaring season. Higher temperatures cause maple trees to convert their energy reserves (stored in the form of complex carbohydrates) into soluble sugars that mix with the water from the tree. Growers harvest the flavored sap by drilling holes in trees.
The sap is about 98% water, and it takes about 40 liters of this maple sap to produce one liter of syrup. During this concentration process, sugar and nutrient levels increase dramatically. The high temperature that comes from boiling the sap causes a series of chemical reactions as the excess water evaporates.
The main components of maple syrup are sucrose and water. Glucose and fructose also contribute to the sweetness of the syrup, but to a lesser extent. Although these three simple carbohydrates are sources of energy, maple syrup is also an excellent source of manganese and riboflavin (vitamin B2), as well as an important source of other vitamins and minerals (zinc, potassium, calcium and magnesium).
The composition of phenolic compounds in maple syrup is even more impressive. Since the beginning of the 20th century, researchers have discovered more than 100 of these molecules in plants. Many of them are antioxidants and contribute to the taste, aroma and color of maple syrup. They are primarily responsible for its recent superfood status.
One of the most promising phenolic components (in terms of biological activities) is a molecule found nowhere but in Canada’s most famous product.
A molecule worthy of national pride
Quebecol – from the name of the province where the majority of the world’s maple syrup production comes from – is a polyphenolic compound (carrying several phenol groups), first isolated in 2011 by a team led by Navindra Seeram at the University of Rhode Island. This compound is so exclusive to maple syrup that it is not even present in raw maple sap! Current knowledge rather suggests that it is the product of chemical reactions that occur during the transformation of the sap into syrup.
First laboratory studies, quebecol inhibited cell proliferation of breast and colon cancer cells. But only a small amount of polyphenols could be isolated, and these tests did not go beyond the preliminary stage. It takes more than 20 liters of maple syrup to isolate less than one milligram of quebecol.
Judging that this syrup would be more useful in kitchens than in laboratories, Normand Voyer, professor of chemistry at Laval University, and I (Sébastien) decided to tackle this supply problem. When I was a doctoral student in 2013, we have published a chemical synthesis route to build this natural molecule much more efficiently in the laboratory from simple precursors. As this work has made quebecol much more accessible, the investigation of its properties has continued and deepened.
In particular, Normand Voyer, Daniel Grenier and their teams, from the Faculty of Dentistry at Laval University, published two studies demonstrating the anti-inflammatory properties of the molecule. This research also made it possible to determine the active part of the molecular structure.
A compound still relevant today
Our 2021 study showed that québecol anti-inflammatory properties may benefit periodontal disease, a serious infection of the gums. We expect more studies to be published this year, including one showing that Quebecol may help in the treatment of a skin condition.
Although evidence for the biological activity of quebecol has been limited to in vitro experiments, these results certainly encourage further study in more complex systems. It is also important to note that the results come from the use of the isolated pure molecule.
These studies do not propose to use pure maple syrup as a medicinal agent against different ailments. Considering the amount of maple syrup one would have to eat to obtain the necessary dose of Quebecol, the harmful effects of a massive ingestion of sugar would overshadow any benefit. It is also difficult to establish the distribution of the molecule in the human body when taken orally.
Either way, these discoveries once again underscore the uniqueness of maple syrup and help reinforce its status as a unique food. Perhaps it contains other equally promising molecules just waiting to be discovered. We bet that this local treasure has not yet revealed all its secrets!