Fermentation Probiotics
By Mike Pettapiece
These so-called ‘good’ bacteria can be found in dark chocolate and in red wine, perhaps two of the most celebrated wonders of fermentation. Probiotics are also marketed in yogurt, in enriched brands of bread and cheeses, in supplements, and in everything from sauerkraut to miso soup.
Google ‘probiotics’, and more than two million hits pop up.
Here’s one of the high priests of this phenomenon in functional foods, Dr. Gary Huffnagle, author of The Probiotics Revolution: “Including probiotics in your diet is like giving your car regular tune-ups before things go wrong.”
The claims made for probiotic benefits seem endless. Physiological effects related to probiotic bacteria include:
- the reduction of gut pH and a healthier GI tract
- stimulation of immune functions and suppression of bacterial infections
- a spur to production of digestive enzymes and of antibacterial substances, such as organic acids and diacetyl
- restoration of the normal intestinal microflora environment upset by diarrheas, antibiotic therapy and radiotherapy
- reduction of inflammation in the GI tract and in airway passages, such as in asthma
At McMaster University and in the Brain-Body Institute in Hamilton, researchers are studying not only the role of commensal organisms in the GI tract but also what is called brain-gut communication. Intriguingly, they are researching whether probiotics might be used as an adjunct in treating brain disorders and their impact on cognitive performance.
All of this focus is directed at the one-celled organisms that populate the colon. The normal human digestive tract contains several hundred types of probiotic bacteria. Most probiotics on store shelves exist within the group of organisms known as lactic-acid producing bacteria.
Probiotics improve the body’s uptake of minerals and vitamins and are often called disease fighters. Huffnagle, professor of internal medicine, microbiology and immunology at the University of Michigan Medical Center, says he used probiotics to treat lifelong allergies and asthma.
Broadly speaking, probiotics are defined (by the World Health Organization) as viable “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host.”
Prebiotics are non-digestible food ingredients that beneficially affect the host by selectively stimulating growth of one or a limited number of bacterial species in the colon. In effect, they are “food” for beneficial bacteria.
Probiotics – meaning “in favour of life” – include certain strains of yeast, lactobacillus acidophilus and bifidobacteria. Prebiotics include inulin, soy and fructo-oligosaccharides, polydextrose, and polyols, such as lactulose and lactitol. The marriage of both has been termed synbiotics.
Industries are spending millions on improving batch fermentation, on reducing the mechanical stresses on probiotic bacteria and yeasts in production, on overcoming harmful metabolites that accumulate in bacterial culture, and on increasing their viability after the reactor – for example, in the extreme conditions of heat-drying or freeze-drying.
Producers are coming up with new encapsulated technologies to enhance the survival of probiotics as they travel to the gut. They are using soy peptides, cellulose and gum to double-coat products. Scientists seek to improve the viability of probiotics by utilizing prebiotic fibres or whey protein gel particles.
It was Louis Pasteur who first preached the benefits of bacteria. But it was Nobel prize-winning Elie Metchnikoff in the early 1900s who pointed to consumption of fermented milk products as a prime reason for the longevity of Cossacks in Bulgaria. He named the microorganism relevant to this fermentation, Bacillus Bulgaricus.
Since then, there has been a flood of studies, both animal and human, looking at probiotics and prebiotics. A study among the elderly, published in the American Journal of Clinical Nutrition in 2001, found consumption of milk supplemented with a Bifidobacterium lactis strain led to enhanced immune function.
A study summarized in the Journal of Clinical Gastroenterology in 2004 found efficacy in some probiotic strains that were linked to reduced severity of microbe-induced gut inflammation, acute gastroenteritis and inflammatory bowel disease. The research also pointed to probiotics helping to reduce the risk of colorectal cancer.
A project by the Nestle company with scientists at Imperial College London showed that strains of Nestle-developed probiotic bacteria can affect metabolism. The study used mice that had been transplanted with human gut microbes, giving them an intestinal microflora analogous to humans.
“Interestingly, the primary influences of the probiotics appear to be via indirect or knock-on effects on the metabolic activities and populations of other gut microbes,” said Prof. Jeremy Nicholson, of Imperial College London. The two probiotics involved had different metabolic effects, “suggesting the possibility of giving probiotic combinations according to a person’s individual metabolic profile,” he said.
At the University of Guelph, researchers are looking into the benefits of probiotics in chicken diets, assessing their impact in decreasing salmonella infections. The hope is that reduced potential for this contamination will lead to fewer incidents of illnesses among consumers higher up in the food chain.
But it is the brain-gut axis that has stirred some of the most exciting probiotic research. Perturbations in the relationship between commensal gut bacteria and the human host are increasingly seen as underlying pathophysiological factors in GI disorders.
This axis model captures the neural pathways that link the brain with the neuroendocrine centres in the gut, the enteric nervous system – sometimes called ‘the little brain’ – and the immune system. Psychological symptoms and comorbidity often exist in irritable bowel syndrome patients. Such communication upsets between the central nervous system and the gut is linked with many phenomena, such as visceral pain, in IBS patients.
In Hamilton, the Brain-Body Institute (BBI) is studying the actions of probiotics on mood disorders and cognitive functioning. Researchers are looking at the mechanisms of signalling between brain and gut that take place along molecular pathways, including the immune and neuroendocrine systems.
When scientists induce gut pain within animals (mice or rats), they find that feeding probiotics to the subjects prevents or improves stress levels, says Dr. John Bienenstock, director of the BBI at St. Joseph’s Healthcare Hamilton. “So there is an affect on the nervous system and it’s those sorts of effects we’re trying to pursue locally . . . and higher up in the body (such as in the lungs and brain).”
Study on animal models is one thing, said Bienenstock, former dean of the faculty of health sciences at McMaster. What is required is more work on human subjects ‘to connect all the dots’. Applying rounds of probiotics to see if they can help in human brain dysfunction situations ‘is a matter of interest but almost no information’ at present.
In the Intestinal Diseases Research Program at nearby McMaster University, Dr. Stephen Collins and fellow researchers are looking at the impact of probiotics on functional disorders in the human gut. In many people, bacterial infections lead to disorders that may not be as severe as say, Crohn’s Disease, but do cause intestinal discomfort.
Often, such people are said to have psychosomatic problems; they are written off as complainers. The E. coli contamination of drinking water at Walkerton in 2000 led to long-term bowel disorders years later.
At McMaster, researchers have linked behavioural changes to perturbation of gut microflora. By using imaging technologies and other techniques on animal models, they have found ‘quite profound changes’ in brain neurotransmitters, said Collins. And they see impacts on appetite-control centres.
Administration of probiotics has a profound impact on improving the behavioural patterns of murine subjects. Next year, researchers will look at probiotics and bacterial influences on the whole question of weight control.
“We were very skeptical when we first got into this,” said Collins, who has worked with probiotics for six years. “But I have to say
. . . the more we look, the more we find. It’s been quite amazing.”
Yet the sheen of probiotic good news has also been tarnished by negative stories. Two dozen people died in a lengthy clinical trial study in Holland that used probiotics to treat patients – many of them very ill – suffering from acute pancreatitis. In that case, researchers administered probiotics like a drug, and not as a food additive.
And yogurt maker Dannon was forced to refute claims of fraudulent allegations in the wake of a class action suit filed earlier this year in a California court. The suit accused the company of spending $100 million promoting clinical benefits of products that the company’s own testing on its Activia product did not support.
The suit illustrated a major challenge facing the probiotics industry as a whole: the need for standardization of probiotic production and just how the benefits of different probiotic strains are measured. Since the cultures are live, it is tough to implement a standard process. That, in turn, can lead to uneven regulatory oversight.
The probiotics issue has landed at Health Canada’s doorstep. The department has not verified the many claims flaunted by makers of probiotic products since, in most cases, the products are not covered under existing regulations.
“We have not approved or authorized any claims surrounding probiotics in Canada,” Health Canada spokeswoman Mary L’Abbé told the CBC earlier this year. The department engaged in public consultations to help develop regulation guidelines.
“We recognized last year that we really did need to take a look at our framework surrounding health claims. There are a number of health claims that really weren’t used in years previously,” L’Abbé said.
Mike Pettapiece, a journalist for more than 30 years, most recently at the Toronto Star, writes and edits the newsletter for the Golden Horseshoe Biosciences Network, based at McMaster University in Hamilton.
