Friday, July 1, 2011

Introducing Kefir

After coming across various blog posts on fermented dairy (yogurt, kefir, cultured butter), I was intrigued.  I placed an order for kefir grains from The KefirLady and started a batch as soon as they arrived in the mail.  Once you start fermenting your own dairy, you've crossed into a another world of hippie-locavore-homecooking that you cannot return from.

Kefir is simply fermented milk.  Its origins have been traced to Caucasus, where the Muslim population regarded kefir as a gift from Allah.  The fermentation is achieved by inoculating a container of milk with a combination of bacteria and yeast, collectively known as kefir grains. The grains metabolize the nutrients in the milk - the lactose and some fatty acids - and in-turn produce carbon dioxide, lactic acid, and small amounts of a host of other compounds, including ethanol.  These benign microorganisms out-compete and actually fend-off pathogenic bacteria, thus preserving the milk without refrigeration.  Kefir is unique because it contains both bacteria and yeast, unlike yogurt which only contains bacteria, and because the grains are re-used again and again with each new batch.  Similar to other fermented foods, kefir is considered a probiotic.

Kefir grains
A probiotic is defined as "microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well being of the host."  Many of the purported health benefits of fermented products are commonly attributed to improved gut health and modulation of the immune system (via the gut), although some have investigated possible anti-cancer properties. While everyone is familiar with probiotics because of the yogurt craze, the idea that fermented foods are healthful is not new.  As implied above, the people of Caucasus had much appreciation for kefir.  But despite the precedence, we cannot yet call probiotic foods a panacea. 

The Cochrane Collaboration has found no benefit in probiotics for inducing remission or maintaining remission in Crohn's disease, which perhaps argues against how strongly probiotics can modulate the immune response.  In regard to general gut health, Cochrane did find limited evidence for reduced c. dificile re-infection and minor improvements in childhood diarrhea.  These trials commonly used isolated  probiotics, so perhaps whole food probiotics are more beneficial.

There is some evidence that yogurt and the lactobacillus bacteria it contains can improve gut health in humans.  However, the most compelling evidence seems to be in regard to relieving constipation, particularly in children and women.  From what I can gather, lactobacillus containing yogurt does appear to relieve constipation, although not necessarily with the consistency asserted by advertisments.  To be sure, my cursory review of the literature does not warrant a definitive assessment for or against the benefits of probiotic foods, but I think there are a few things to keep in mind.  

The whole area of probiotic research suffers from inconsistant trial design, inconsistent use of bacteria and probiotic sources, and trouble defining exactly what "gut health" is.  The role of gut bacteria and health is compelling, but our understanding is still in its infancy.  We know that illness is associated with different gut microflora, such that obese children and those with Crohn's disease have different gut microflora composition than normal controls.  And as I learned from this past weekend's American Diabetes Association conference, these microflora are partially malleable e.g bariatric surgery changes the prevalance of different bacteria within the same individual.  However, we still do not understand what these associations and changes mean.  And while this research will likely provide improved treatment for gut disorders and diseases, we are still unsure how readily one food (kefir, yogurt, fermented vegetables) will change our gut bacteria and subsequently our health.  But I still think trying kefir is worthwhile.

From my experience, and I know that I am not alone, conventional medicine does a poor job with general gut health.  Conventional medicine clearly has a grasp on serious digestive diseases such as colon cancer, but more nuanced problems, such as food intolerances or sensitivities, usually evoke eye-rolling or a psycho-somatic diagnosis.  The diagnosis-by-exclusion Irritable Bowel Syndrome is likely a symptom of this general ignorance.  Although to be fair, I am not convinced that alternative medicine understands gut health as much as it purports to.  So given that fermented foods are both traditional and whole foods (avoid sugar containing yogurts!), and given their potential benefit, I think they are absolutely worth trying.  And because I make the kefir myself, I know that it has the probiotics that it is supposed to.  And if it is nothing but nutritional mysticism, at least it is low carb mysticism (the bacteria eat the milk sugar so that I don't have to).  And hey, instead of a cat to keep me company, now I have kefir grains to come home to.

1 comment:

  1. I gave up on kefir as I became seriously constipated for the 1st time in my life after using it for a few weeks. Now I'm verry suspicious of all the health claims. I kept using it after getting constipated, I increased my intake of water, and magnesium, neither did anything to give me relief, only stopping kefir ended the constipation. I will never touch the stuff again. Maybe it was just too much calcium from the milk, I really don't know, but it was a horrible experience.