Thyme, carrots and elderflower can do more than just be fragrant and taste good. They also contain ingredients that have a positive impact on type 2 diabetes. This is what results show from a number of studies at Aarhus University in collaboration with University of Copenhagen and University of Southern Denmark, where selected plants have been screened for compounds that can potentially prevent type 2 diabetes.

The hypothesis was that the plants contain bioactive ingredients that can increase the uptake of glucose in muscle cells and stimulate the pancreatic production of insulin. The plants that the researchers had under the microscope were vegetables, herbs and flowers. Specifically, the researchers screened carrots, cabbage, broccoli, thyme, summer savoury, elderflower, roseroot and purple coneflower for potentially beneficial compounds.

The choice of plants was not a shot in the dark. The researchers chose the eight plants based on either their medical background such as traditional anti-diabetic agents or their importance within food and nutrition.

Type 2 diabetes is a global epidemic

There is good reason to search for agents that can prevent type 2 diabetes. Type 2 diabetes is a serious ailment that is becoming increasingly prevalent globally. Much of the explanation for this lies in our lifestyle as we eat too much and too unhealthily and have a lifestyle that is too sedentary. There is also a tendency that you can be genetically predisposed to the disease.

- Modern man has trod the long path of evolution but has now created a mechanised world for a more comfortable life. This fact is unfortunately associated with certain challenges, says PhD Sumangala Bhattacharya on the prevalence of type 2 diabetes. As part of her doctoral studies at the Department of Food Science at Aarhus University, she helps to identify the plants containing bioactive ingredients that can prevent type 2 diabetes.

What is type 2 diabetes?

To understand why the researchers chose to focus on specific substances in these plants, it helps to have some knowledge of type 2 diabetes:

The disease is a chronic metabolic disorder that disturbs the regulation of blood sugar levels. When we have eaten something, the food is broken down to, among other things, glucose. This sends a signal to the pancreas that it must secrete insulin. Insulin causes cells in the muscles, liver and body fat to absorb the glucose. Insulin also regulates the level of glucose in the blood between meals. When this system functions well, there is neither too much nor too little glucose in the blood.

Problems arise when the liver, fat and muscle cells become insulin-resistant. This means that they do not respond to insulin and neglect their job of absorbing glucose from the blood. The elevated blood sugar levels make the insulin-producing cells in the pancreas – the beta cells – produce more insulin. The beta cells become overworked and if the insulin-resistance persists over a longer period, the beta cells are destroyed and can no longer produce insulin. This results in a chronic state of elevated blood sugar and thus a vicious cycle has started.

Flowers, herbs and vegetables are all effective

Healthy eating habits and exercise go a long way to counteract the problem, but if your system has been pushed too far, you need medication to treat the disease. The medications used to treat type 2 diabetes are not always without side effects. It would therefore be good to have alternatives. It is here that the bioactive ingredients from the plants enter the picture.

The researchers were looking for ingredients that can increase the survival of the beta cells in the pancreas and improve their ability to produce insulin. The eight plants that were screened were tested to see how capable they were at increasing the glucose uptake in muscle cells, as an indicator that the insulin is working according to plan. It turned out that thyme, purple coneflower, carrots, elderflower and roseroot were very good at this, with extracts from carrots, thyme, elderflower and roseroot producing the largest increases in glucose uptake.

Elderflower contains useful compounds

In subsequent experiments the researchers turned their attention on elderflower in order to identify the active substances since there appears to be something in elderflower that affects both blood sugar levels and obesity.

- Elderflower contains substances that have some marked bioactive effects and help to regulate the body's turnover of glucose and fat. We found that naringenin was one of the most potent substances in elderflower in this respect. Naringenin is particularly good at increasing glucose uptake and lowering fat accumulation, explains Senior Scientist Niels Oksbjerg from the Department of Food Science at Aarhus University.

In yet another part of the experiment, the researchers examined the three natural phenols caffeic acid, naringenin and quercetin. These are all found in foods like Brussels sprouts, grapefruit, onions and apples. The researchers examined the substances for their ability to increase the secretion of insulin during acute and chronic states of elevated blood sugar levels. They also examined how the genes that are involved in the process were affected – that is, the extent to which they were expressed.

All three phenols increased the production of insulin when sugar levels were elevated. Phenols also affected the expression of the genes involved in beta-cell stress, survival and functioning.

- Our results show that the exploitation of bioactive substances from plants for producing new types of remedies against type 2 diabetes has potential, says Niels Oksbjerg.

The project was financially supported by Innovation Fund Denmark and was a collaborative project between the University of Copenhagen (project leaders), University of Southern Denmark, Aarhus University and the Technical University of Denmark.

For further information please contact: Senior Scientist Niels Oksbjerg, Department of Food Science, email: niels.oksbjerg@food.au.dk, telephone: +45 8715 7809, mobile: +45 3011 3204