Following on in the series on prebiotics, this week we will be covering a very underappreciated and utilised prebiotic known as lactulose.
The few people that may already be familiar with this substance may be confused at the moment, and understandably so. Lactulose is generally used as a laxative and is recommended to treat constipation.
Lactulose is a semi-synthetic disaccharide (two simple sugars joined together) composed of both galactose and fructose. As a prebiotic lactulose escapes digestion in the small intestine and reaches the colon intact where it can be metabolised by specific bacteria (2).
While anything synthetic seems less than ideal in my mind lactulose does have an incredibly long history of use, dating back 40 years, with no evidence of serious side effects (3).
A very interesting review looking to summarise the scientific findings of lactulose starts with a powerful statement on the effects of lactulose
“The major principle of action is the promotion of growth and activity of lactic acid bacteria in the gut which counteract detrimental species such as clostridia or salmonellae. This shows that prebiotic action, if used accordingly, can have medically significant effects”
Another review summarised a number of findings that included
- Reduction in urinary tract infections
- Increase in Bifidobacteria species
- Increase in Lactobacilli species
- Increased production of short chain fatty acids (SCFA’s)
- Drop in colonic pH
A very nice table presented in the same review listed some past and current research that points to lactulose’s beneficial uses including:
- Acidification of gut contents
- Ammonia depletion
- Increased peristalsis
- Increased osmotic pressure
- Softening of stool
- Facilitated defecation
- Selective bacterial growth
- Stabilisation of ecosystem
- Inhibition of toxin-producing enzymes
- Prevention of gallstones
- Decrease of serum lipids
- Shorter residence time of toxins
- Prevention of carcinoma (colorectal and maybe other organs)
- Prevention of gastrointestinal infections (Rotavirus, Candida, etc.)
- Prevention of urogenital infections
- Prevention of radiation enteritis
- Anti-endotoxic (numerous applications possible)
- Glucose- and insulin control
- Improved mineral absorption
- Prevention (therapy) of inflammatory diseases (e. g. diverticulitis)
So to summarise the effects of lactulose stems from the selective feeding of both Bifidobacteria and Lactobacilli species in the colon. These beneficial bacteria have a range of beneficial effects including the production of short chain fatty acids that, among other benefits, reduce the colonic pH. This drop in pH is less favourable for the more pathogenic microbes and results in reduced numbers.
A review looking into beneficially altering the gut flora to assist in the treatment of inflammatory bowel disease had a nice summary on the two beneficial genera Bifidobacteria and Lactobacilli.
“Lactobacilli and Bifidobacteria, and producing acidic products of fermentation inhibitory to pathogens, exert antagonistic effects towards other microorganisms. They compete with other microbes for substrates and site of colonisation. The protective mechanism exerted by these bacteria have been termed colonisation resistance”
Have you had any experiences with prebiotics? Share your thoughts in the comments below.
References and Resources
- Fully Functional series on Prebiotics
- Medical, nutritional and technological properties of lactulose. An update.
- Promotion of a favorable gut flora in inflammatory bowel disease.