There may be a relationship between kefir and obesity.
I’m becoming increasingly convinced of the benefit of fermentation, that enriching beneficial gut bacteria has widespread effects on wellbeing and health. I’m still near the beginning of this journey and learning all the time. I’ve posted a series of articles linked to kefir, not because I’m an expert, but based of the apparent benefits accrued over the last two months from a small glass of kefir each day. I should also say that Maggie has lost a lot of weight over the time she has been drinking kefir, but, she has also been exercising. However weight loss isn’t my only reason for writing about this subject. A few months ago I felt obliged to take a course of antibiotics, I think it was a mistake ( I am aware of the downsides of this kind of medication) but it’s water under the bridge now. The subsequent decline in my overall health was striking. I started to have trouble concentrating and sleeping, I got a cold, suffered from reflux and saw an augmentation in weight.
I didn’t really connect these things with the antibiotics until I noticed that my bowel movements changed significantly. If you are new to the gut bacteria scene you might feel a little uncomfortable around talk about bowel movements, don’t be. A regular healthy bowel movement is one of the signs of a healthy balance in gut bacteria. So when I noticed I wasn’t going to the toilet regularly I though about the possible impact of antibiotics on my gut. I started to take kefir more regularly whilst keeping my usual prebiotic and probiotic consumption at the same level. The difference was gradual but pretty much everything started to improve after about five days. Two months later things are back where there were before the antibiotics. I’m much healthier, bowels are back to normal and……..I’ve lost weight without any exercise.
This isn’t a morality narrative about the harm of antibiotics. I believe antibiotics represent a life saving technology, and in the right place and time are essential. It’s their inappropriate overuse which I think is harmful.
My own anecdote is that I think it took two months to return the state of my gut bacteria to somewhere like normal, and I am a daily consumer of natural prebiotics and probiotics. In all of this story things pretty much fitted my modest understanding of the underlying science except the weight loss. I know that lack of diversity in gut bacteria is correlated with obesity generally but I hadn’t come across any research papers linking kefir to weight loss. If you can improve your gut health and pull your body weight closer to its optimum level this has to be a win-win. So I started to look through the scientific literature. The most recent research is featured here.
Are their differences in traditional and commercial kefir?
This is the second part of the feature, you’ll find part one here.
Despite my scientific training, regular followers of my blogs will have realized I have an established scepticism for extravagant scientific claims. I am a fan of science generally but feel the need to maintain a discriminating eye and treat each scientific claim on its merits. However a recent study into the relationship between kefir and obesity has been worth a closer look.
In a research paper titled Traditional kefir reduces weight gain and improves plasma and liver lipid profiles more successfully than a commercial equivalent in a mouse model of obesity, Bourrie, Cotter and Willing found that kefir appeared able to meditate metabolic health. This study compared the ability of traditional with commercially produced kefir to mediate mouse weight gain, plasma cholesterol, and liver triglycerides. Four traditional and one commercially available kefirs were used in the experiment. Commercial kefir was shown to have no beneficial effect whilst two of the traditional kefirs demonstrated a reduction in the rate of weight gain and increase in blood cholesterol. This was (as far as I know) the first ever study comparing mass produced with traditionally produced kefir, so the research must be regarded as preliminary. It was a study with mice so the extent to which results can be generalised to humans is uncertain.
The research concluded that when also considered in relation to the modulation of the gut microbiome, traditional kefir has the potential to mediate obesity through the improvement to metabolic dysfunction.
The report also explained that different forms of traditional kefir do not generate identical microbial populations. It is assumed that this could be linked to variable health benefits. Further that whilst Lactobacillus, Lactococcus, and Leuconostoc would be expected to be found in most forms of kefir, acetic acid bacteria was not found in a majority of commercial products. Research has also suggested that traditional kefir possesses highly complex fungal communities (including, S. cerevisiae, Pichia fermentans, Kazachastania unispora, and Kluyveromyces marxianus and lactis) not always found in commercial products.
In conclusion, three take home points:
This is preliminary research, it’s early days!
Traditional kefir may support improved cholesterol and fatty acid metabolism.
Traditional kefir appear to offer a much greater microbial diversity to the host than commercially produced kefir.
There is growing evidence that gut bacteria is linked to obesity. Preliminary experiments with mice appear to be supported by human studies.
Ongoing research into the role of the microbiome (bacteria in the gut) in human wellbeing is at a very early stage. But the frequency of media headlines linking gut bacteria to health is growing. As with all areas of science, claims which have not been verified in clinical trials and subsequently replicated must be treated with caution. Nevertheless the evidence of a relationship between gut microbiome diversity and obesity has been repeatedly demonstrated in mice.
The microbiome is a term used to describe all of the genetic material of a microbiota, the entire range of microorganisms present in a particular context, in this case the human gut.
There have been a number of studies which show that obese mice tend to have fewer different types of gut bacteria than thin mice. The thinking is that a greater range of gut bacteria is likely to positively influence the way that the digestive system breaks down food. Having more (types of) bacteria is linked to efficient processing of what we eat, with the results of a tendency not to be obese. Recent research reported in The Independent looked at the weight gained by 1,632 female twins over nine years. The study calculated that only 41% of the weight increase could be explained by genetic factors.
On closer inspection it was estimated that becoming slimmer or maintaining the same weight was connected to the consumption of dietary fibre (typically found in whole grains, fruit and vegetables). The study also discovered that the women who had gained weight, had a lower diversity of gut bacteria. These findings were in line with similar studies with mice. Although not yet conclusive the overall evidence linking the shape of our body and the composition of our microbiome is growing.