Research shows that probiotics might help prevent allergies and obesity in children when taken by their mothers during pregnancy.
Ever heard of the hygiene hypothesis? This theory, proposed by medical epidemiologist Dr David P. Strachan in a 1989 paper in the British Medical Journal, suggests that the current increasing incidence of allergic diseases like eczema and asthma, are due to decreasing family size and the increasing cleanliness of our households today.
These factors combine to create an environment where children are less likely to be infected by germs, but, as Dr Strachan proposed, consequently, more likely to develop allergies.
Since then, scientists have expanded this hypothesis to include the close interrelationships between diet, the human immune system, the microorganisms within the human body, and the origins of human disease.
Among those working on this expanded theory are scientists in the University of Turku, Finland's Nutrition, Allergy, Mucosal Immunology and Intestinal Microbiota (NAMI) programme, headed by Prof Dr Erika Isolauri.
Prof Isolauri, the chief physician at Turku University Hospital's paediatric department, was in Kuala Lumpur recently to give a scientific lecture on "Probiotics for Maternal and Child Health" to healthcare professionals.
Speaking to journalists before the talk, she comments that with the improvements in our modern lifestyles, the incidence of infectious diseases has decreased, but chronic diseases have increased in their place.
Around one child in four displays some form of allergy in the world today, she shares.
"Another problem we face is obesity. It is surprising that the rates throughout the world are exponentially increasing - we have an epidemic.
"We also have other (autoimmune and inflammatory) diseases, for example, Crohn's disease and inflammatory bowel disease. My country has the highest rates of type 1 diabetes.
"Therefore, we have to look at our environment - what has changed."
She explains: "Even though we have genes, we realise now that environmental influences have permanent effects on our later health. The environment influences how the genes express themselves. The genes themselves only affect a few per cent(age of expression)."
In fact, Prof Isolauri says: "The funny thing is our microbiota and our genes have not changed; our gut is still in the Stone Age.
"So when the risk of infectious diseases was high, these bacteria were educating the body to fight off infections."
She adds: "In the Stone Age, when you could only find food every few days, they (our gut bacteria) were harvesting (and storing) energy, which, in our affluent times now, is not good."
Excess energy is stored in our bodies in the form of fat. So, while maximising the energy output from food during our prehistoric hunting-and-gathering days was probably crucial to survival then, it is now part of the reason we are facing an increase in obesity rates, considering the relative ease of access many of us have to food nowadays.
Infants nowadays are increasingly likely to be born via Caesarean section, and increasingly unlikely to be exclusively breastfed for at least the first six months of their lives.
This has consequences on their immune system.
As foetuses acquire their initial immunity from their mothers, this means that they have a heightened immune system that is quite sensitive to allergens, and could potentially lead them to develop allergies after being born.
However, as Prof Isolauri explains, certain hormonal, metabolic and immunological influences that only occur with the approach of labour help to modulate and mature the child's immune system, so that it is not overly sensitive to allergens upon entering the world.
"Labour creates a stress situation, and if the stress is not too much, it is beneficial for the child," she says.
This process does not occur when mothers choose elective Caesarean sections, which is an increasing trend throughout many parts of the world.
The maturation of a newborn's immune system is also affected by the types of microorganisms that colonise their gut during the first few days of their lives.
In addition, Prof Isolauri and her colleagues have found evidence that the increased presence of certain Bifidobacterium strains in babies protects against excessive weight gain later in life.
Interestingly enough, studies have found that these particular bacterial strains are decreased in overweight pregnant mothers, compared to normal-weight ones.
According to Prof Isolauri, babies are most likely to be colonised by good bacteria when their mother is healthy, has a good diet, and delivers her baby naturally.
But considering the increasing trends of Caesarean section births and decreasing trends of exclusive breastfeeding worldwide, she and her team are looking into the administration of probiotics to pregnant and lactating mothers as an alternative way of providing infants with these bacteria.
Probiotics are essentially live microorganisms that give a health benefit to those that take them, but in this case, the NAMI researchers found that the benefits extend to both mother and child.
In their first study, Prof Isolauri and her colleagues found that administration of probiotics during the last stage of pregnancy modified the mother's breastmilk to the child's benefit, allergy and weightwise, but had no effect - positive or negative - on the mother herself.
In their follow-up study, the researchers decided to see if providing probiotics consisting of Lactobacillus and Bifidobacterium strains, along with dietary counselling, to pregnant mothers in the first stage of pregnancy up to lactation, would have better effects on their babies.
"We were treating allergic families, but surprisingly, we had an effect on the mothers. We could reduce significantly the glucose levels of the mothers," says Prof Isolauri.
She adds: "When the mother was metabolically healthy early on, and then developed gestational diabetes mellitus, we could reduce the risk of gestational diabetes mellitus.
"But if the mother was already overweight and had poor sugar control, the benefits were even better."
Although research in this area still has a lot to cover, Prof Isolauri says that in her home country of Finland, most expecting mothers now take probiotics of their own accord during their pregnancies.
And she observes that there is now a plateau in terms of allergic admissions to their hospitals.
When asked if there were any probiotic strains in particular that are good for expecting mothers, she says: "I would say we do not know exactly which strains are the best for pregnant women.
"But we have studies that look at the breastmilk of healthy women with healthy babies, and B. longum and B. lactis were very high."
She adds that they are now studying the different Lactobacillus strains present in breastmilk.