Almonds, as well as being high in vitamin E and other minerals, are also thought to have other health benefits, such as reducing cholesterol. Recently published work by the Institute of Food Research  (contact information:  Norwich Research Park, Colney Norwich, NR4 7UA, UK)  has identified potential prebiotic properties of almonds that could help improve our digestive health by increasing levels of beneficial gut bacteria.

The Skinny on Prebiotics 

Our digestive system maintains large population of bacteria that live in the colon. Prebiotics are non-digestible parts of foods that bacteria in the colon, can use to fuel their growth and activity and improve healt. These 'good' bacteria form part of our body's defense against harmful bacteria and play a role in the development of body's immune system. The prebiotics work by stimulating the growth of these bacteria. However, in order to get to where they are needed prebiotics must be able to get through the upper part of the intestine without being digested or absorbed by the body.

Today, a prebiotic nature has been attributed to many food components without due consideration to the criteria required. In particular, almost every food oligosaccharide and polysaccharide (including dietary fiber) has been claimed to have prebiotic activity, but not all dietary carbohydrates are prebiotics. To be considered a true food prebiotic the food component or ingredien must:

• Resist host digestion, absorption and adsorption processes;
• Is fermented by the microflora colonising the gastrointestinal system;
• Selectively stimulates the growth and/or the activity of one or a limited number of bacteria within the gastrointestinal system.
• Be validated through appropriate clinical feeding trials.

Reference:  Gibson GR, Berry Ottaway P & Rastall RA. Prebiotics: New Developments in Functional Foods

Almond Prebiotic Study 

Funded by the Almond Board of California, IFR scientists first used the Model Gut, a physical and biochemical simulator of the gastro-intestinal tract, to subject almonds to the same conditions experienced in the stomach and small intestine. They then added the digested almonds to an in vitro batch system to mimic the bacterial fermentation in the large intestine and monitored its effect on the populations of intestinal bacteria.

The study found that finely ground almonds significantly increased the levels of certain beneficial gut bacteria. This effect was not seen when the fat content was removed from the almond preparation, suggesting that the beneficial bacteria use the almond lipid for growth, and this is the basis for the prebiotic effect of almonds.

Previous studies have shown that the amount of available lipid is reduced if the almonds are not processed, for example by grinding as in this study or by chewing. The length of time the almond spends in the digestive system also affects the amount of available lipids and proteins. More detailed studies on the digestibility of almonds are now required, and the prebiotic effect of almond lipids needs to be tested in human volunteers.