- Polyphenols are a group of molecules found in plants and plant-derived foods, which have a range of known health benefits due to their antioxidant activity.
- They are known to bind with amino acids—the building blocks of proteins—which also occur in foods, and can enhance their antioxidant effects.
- Previous studies have looked at the effect of polyphenol-binding with the proteins found in meat.
- A team of researchers has now shown that when the polyphenols found in coffee bind with an amino acid found in milk, the antioxidant and anti-inflammatory effects in mouse cells in vitro are enhanced.
One of the reasons why plant-derived foods might provide some health benefits, such as protection against
Polyphenols, however, can interact with and alter the activity of macrophages, which is thought to be behind their health-giving properties.
One group of researchers from the University of Copenhagen, Denmark, previously looked at the effect of polyphenol binding to proteins in meat products, milk, and beer.
Recently, they decided to investigate coffee. Their latest research sought to explain how the binding of this particular polyphenol with the amino acid cysteine affected its inhibitory effect on inflammation in cells.
They published their results in the Journal of Agricultural and Food Chemistry.
Lead author Prof. Marianne Nissen Lund explained to Medical News Today why they decided to investigate this link.
“We [previously] found that polyphenols react with proteins in different types of foods, including meat products, added plant extract (e.g. spices), milk, added green tea extract, and beer,” she said.
“The reason for starting with investigating polyphenols from coffee is because these polyphenols have a more simple structure than, for instance, those found in green tea, so they are a bit easier to work with when we need to perform our chemical analyses in order to prove that they actually exist in foods,” she added.
Polyphenols are the most abundant source of antioxidants in our diets and are thought to reduce oxidative stress in the body, which occurs naturally.
However, they also contribute to counteracting the aging process and are anti-inflammatory. This effect is thought to occur as polyphenols reduce oxidative stress, which can help
Coffee is a source of polyphenols, including caffeic acid, which is also found in sunflower flour. It is known to inhibit the oxidation of lipoprotein, which acts like cholesterol as it is sticky and can narrow and block blood vessels.
Inhibiting the oxidation of lipoprotein is thought to inhibit this effect, thus reducing the risk of cardiovascular disease.
Previous research has suggested that polyphenols can help to reduce the immune response in people who are sensitive to milk, said Dr. Adil Maqbool from Allama Iqbal Medical College in Lahore, Pakistan, who was not involved in the study.
“There is some evidence to suggest that combining polyphenols, naturally occurring compounds found in certain plant-based foods, with dairy products may help reduce the immune response in people with lactose or casein intolerance,” he told Medical News Today.
“The exact mechanisms behind this interaction are not yet fully understood, but it is believed that polyphenols may help to mitigate the immune response by reducing inflammation,” he added.
There are two reasons why somebody might be sensitive or allergic to cow milk products. People might have an intolerance of lactose—the sugar that occurs in milk—due to a lack of lactase, the enzyme that digests the sugar. The cause of this could be genetic.
Meanwhile, people who are allergic to cows’ milk produce an immune reaction when exposed to casein, a protein found in the milk.
One of the amino acids found in milk is cysteine, and so far, there has been little research into the effect of the binding of polyphenols found in coffee with this amino acid.
Carrying out the experiments in vitro, researchers used a cell line derived from mice to investigate the inflammatory response of two polyphenols—caffeic acid and chlorogenic acid when bound to cysteine and compared this with the inflammatory effect of cysteine unbound.
They found that when cysteine was bound to the polyphenols, the inflammatory response was reduced.
Researchers then looked at the RNA (a signaling molecule involved in transcribing and translating DNA) present in these cells to determine which genes were activated and which ones were less active. They found that genes involved in the inflammatory response were downregulated when cysteine was bound to the polyphenols.
The team wants to do further research in animals to see if these findings could be recreated in vivo and potentially lead to a greater understanding of how to reduce the immune reaction to milk in humans.
“The impact could be that—now that we know that the reaction between proteins and polyphenols enhance their anti-inflammatory effects —to exploit this knowledge in foods,” Prof. Lund said.
“Due to the green transition and the need to develop and consume more plant-based foods, we may be able to develop new plant-based foods that are even more healthy if we can control these reactions in the foods,” she added.
But before we jump to conclusions, Prof. Lund stressed that scientists will have to see whether these effects are also valid in the human body.
Dr. Maqbool agreed with the findings of the paper but warned more research was needed.
“I do agree with the findings. However, it is important to keep in mind that more research is needed to fully understand the interactions between polyphenols and dairy and their impact on lactose and casein intolerance.”
— Dr. Adil Maqbool
“In the meantime, individuals with lactose or casein intolerance may benefit from avoiding dairy products or seeking alternative sources of calcium and other nutrients,” he added.