CAN FIBRE INTAKE INFLUENCE MY IMMUNE SYSTEM?
With the recent outbreak of COVID-19, individuals are doing everything they possibly can to keep their immune system functioning at its best to prevent themselves from getting sick. When it comes to fibre, the common association is usually with digestive health but could fibre intake be linked to immunity health too? Let’s take a closer look.
While most foods contain a combination of different fibres, it’s important to first understand the different types of fibre.
You can think of soluble fibre as the guy that sits at the front of the taxi and gets everyone’s attention to jump in the taxi. Although he attracts people to the taxi, he slows down the taxi during this process. In the same way soluble fibre attracts water. During digestion it turns into a gel and slows down digestion. Examples of soluble fibre include nuts, seeds, barley, oats, peas, lentils and some fruits and vegetables.
Insoluble fibre on the other hand is the people in taxi. They take up space in the taxi but as soon as more people jump in the taxi it carries on moving to its destination. Insoluble fibre therefore adds bulk to the stool. It also helps food to pass through the stomach and intestines faster. Examples of insoluble fibre include whole grains, wheat bran and vegetables.
THE EFFECT OF FIBRE ON THE IMMUNE SYSTEM
The gastrointestinal tract is the ‘largest immune organ for humans’1. The gut immune system is dependent on dietary constituents, especially prebiotics in order to function optimally2. Prebiotics stimulate the growth of ‘good’, health promoting bacteria in the colon. The most extensively studied dietary fibres are inulin and other oligofructoses.
There is strong evidence that the consumption of inulin and oligofructose increase the amount of lactic acid in the human colon3. The beneficial role of lactic acid bacteria on the immune system in humans has been well established4.
Inulin and other oligofructoses play a role in stimulating the growth bifidobacteria. Bifidobacteria produce short chain fatty acids and stimulate the immune system2. There are numerous other fibres that are fermented to generate short chain fatty acids however the effects of bifidobacteria from non-oligofructose fibres is not yet well established. In addition to stimulating the immune response, it is proposed that bifidobacterial have the following health benefits1:
- Protection against intestinal infection
- Lower the intestinal pH for formation of acids
- Reducing the number of potentially harmful bacteria
- Production of antioxidants and vitamins
- Intestinal function activation and assistance in digestion and absorption
Soluble fibre also plays a role in immune health. In simple, it acts as the army leader calling for peace. It changes the immune cells from being pro-inflammatory (promoting inflammation) to being anti-inflammatory by increasing the production of a protein called interleukin-45.
HOW MUCH FIBRE DO YOU NEED TO CONSUME?
The American Heart Association recommends an intake of 25-30g dietary fibre from a variety of food sources6. As explained, most foods contain a combination of different fibres so focus on including a variety of food sources to meet your fibre requirements rather than focussing on the types of fibre you consume.
So, as explained above, the answer to the question is yes! Perhaps the saying ‘an apple a day keeps the doctor away’ actually refers to the apple’s fibre content boosting your immunity? Now that’s food for thought...
- Vos AP, M'Rabet L, Stahl B, Boehm G, Garssen J. Immune‐modulatory effects and potential working mechanisms of orally applied nondigestible carbohydrates. Crit Rev Immunol. 2007;27:97–140
- https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S00071145020009 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S000711450200099595
Author: Sonal Ratan RD (SA)