It has long been known that blueberries contain large quantities of antioxidants and vitamins. Now new research from Lund University has shown that blueberry fibre is also important and can alleviate and protect against inflammatory bowel diseases such as ulcerative colitis. The protective effect of blueberries is further enhanced if the berries are eaten together with probiotic bacteria.
The aim of the project was to see if different types of dietary fibre and probiotic bacteria (‘healthy bacteria’) such as lactobacillus and bifidobacteria can help to alleviate and prevent the risk of ulcerative colitis and bowel cancer. “New knowledge in this area is also interesting for those who don’t think they are at risk of bowel diseases. In recent years, the research community has come to realise that our health is controlled to a high degree by what happens in our intestines", explain Camilla Bränning, Doctor of Applied Nutrition and Åsa Håkansson, doctoral student in Food Hygiene at the Division of Applied Nutrition.
The researchers tested different diets of blueberry skin, rye bran and oat bran with or without a mixture of probiotic bacteria. The results showed that the protective effect of blueberries was enhanced if they were eaten together with probiotic bacteria. "The probiotics were shown to have a protective effect on the liver, an organ that is often negatively affected by inflammatory bowel diseases", explains Åsa Håkansson. Blueberries contain large quantities of polyphenols, which have an antimicrobial and antioxidant effect. The combination of blueberries and probiotic bacteria reduced the amount of bacteria that cause inflammation in the intestines, while the amount of healthy lactobacillus increased.
Åsa Håkansson and Camilla Bränning also observed that if the blueberries were eaten together with probiotics, the levels of butyric acid and propionic acid in the blood increased. These two substances are formed when fibre is broken down and are known to be an important source of energy for the cells of the intestines. Lately they have also been shown to have a positive impact on the immune system. It appeared, quite simply, that the absorption of these substances was facilitated when probiotic bacteria were present. “What surprised us was that such a large proportion of the butyric acid was not only absorbed by the cells of the intestines but also transported to the blood. Previously it was believed that the intestinal cells used all the butyric acid, but this is clearly not the case", observes Camilla Bränning, who recently presented a thesis on the subject. “A further explanation for the extremely positive effect of blueberries could be that the berries’ fibre is not broken down to the same extent in the large intestine, but rather forms a large bulk. This means that substances that cause inflammation do not come into contact with the intestinal mucosa, but rather become embedded in the fibres. These substances then exit the body in a bowel motion", explains Camilla Bränning.
The researchers also saw that rye bran was broken down further along the large intestine, in the same place that ulcerative colitis and bowel cancer often develop, and that the rye bran produced large quantities of butyric acid and propionic acid there. On the other hand, the fibres in the oat bran were broken down earlier in the intestine. However, the most striking result was that the blueberries produced such a good effect compared with both the rye bran and the oat bran.
Between 15-20 per cent of all Swedes suffer from abdominal pain, diarrhoea or constipation, which result from bowel diseases or less easily defined bowel problems. Ulcerative colitis is one of the diseases that go under the collective name of IBD, inflammatory bowel diseases. It can lead to bowel cancer and affects around 1 000 people each year. Camilla Bränning defended her doctoral thesis in January 2010. Read a summary here: http://www.lu.se/o.o.i.s?id=12588&postid=1520883. Åsa Håkansson will present her thesis later in the spring.
For more information please contact Camilla Bränning, researcher in Applied Nutrition and Food Chemistry, +46 (0)46 222 47 27, Camilla.Branning@appliednutrition.lth.se or Åsa Håkansson, researcher in Food Hygiene, +46 (0)46 222 83 26, Asa.Hakansson@appliednutrition.lth.se. Photo of Camilla Bränning, researcher at Lund University.
