Several months ago, I reported on two studies published in the medical journal Nature by Jeff Gordon, a Washington University Scientist intent on investigating correlations between gut bacteria and weight.

Among Gordon’s findings was the fact that his obese and lean volunteers had substantially different compositions of bacteria in their guts. Obese volunteers had 20 percent more of a bacterial species called firmicutes in their gut, but harbored almost 90 percent less of another bacterial species called bacteroidetes than lean volunteers.

Interestingly, when obese subjects were put on a low-carb, low-fat diet, the composition of the bacteria in their guts started to adjust to more closely resemble the ratios of bacteria seen in their lean counterparts.

Similarly, the team found that mice injected with gut bacteria from other obese mice gained about twice as much weight as mice injected with bacteria taken from the stomachs of lean mice, strongly suggesting a direct relationship between the relative abundance of certain bacteria in the gut and the tendency of an individual to gain weight.

This week, a new study revealed similar findings, demonstrating that the mix of bacteria in a baby’s gut may predict whether the infant will become overweight or obese later in life.

In a study published in the March issue of The American Journal of Clinical Nutrition, researchers at the University of Turku in Finloand reported that babies with high numbers of the bacterial species Bifidobacteria and low numbers of the bacterial species Staphylococcus aureus may be protected from excess weight gain.[1]

The Finnish team selected 49 children from a larger long-term study aimed at evaluating the effect of probiotics on allergic disease. The babies had been evaluated at birth, five more times before age 2, and then again at ages 4 and 7. The researchers in the original study had also tested for intestinal microbes in fecal samples collected at 6 months and 12 months.

Of the 49 subjects selected from the larger study, 25 were overweight or obese at age 7, while 24 subjects of the same age were of normal weight.

When the Finnish team examined the fecal samples taken from the children earlier in life, the average bacterial counts of Bifidobacteria taken at 6 months and 12 months were twice as high in those children who were at a healthy weight as in those who had become obese.

Those who stayed at a healthy weight also had lower fecal S. aureus levels at 6 months and 12 months than did those who got heavy.

The researchers speculated that S. aureus may trigger low-grade inflammation that also contributes to developing obesity, a statement which supports biomedical researcher Trevor Marshall’s view that obesity is not a cause for other diseases such as heart disease and stroke, but is an inflammatory disease in its own right. As with other chronic diseases, it is directly related to a patient’s bacterial load.

Since Bifidobacteria are prevalent in the guts of breast-fed babies, the Finnish team also suggested that their findings may help explain why breastfed babies have been found to be at lower risk for later obesity. Other studies have repeatedly found that breastfed babies have a 13 to 22 percent reduced risk of excess weight or obesity in childhood.

“The finding that the lean children harbored higher levels of Bifidobacteria at younger ages is very intriguing,” commented Ruth Ley, a research assistant professor at Washington University School of Medicine in St. Louis. According to Ley, the Finnish study is unique, because it collected information over several years, making it possible to look for differences in gut microflora.

Someday, the Finnish researchers speculated, tinkering with gut flora may help prevent or treat obesity. Little do they know (at least we presume so) that patients on the Marshall Protocol are already doing much more then simply tinkering with the pathogens in their guts. By using a combination of low-dose antibiotics and Benicar they are able to gradually wear away at pathogenic species in the gut, allowing their GI tracts to re-establish an optimal composition of gut flora after several years of therapy.


  1. Kalliomäki M, Carmen Collado M, Salminen S, Isolauri E. Early differences in fecal microbiota composition in children may predict overweight. Am J Clin Nutr. 2008 Mar ;87(3):534-8. []