Health effects of kefir and/or yogurt?
February 25, 2016 3:43 PM   Subscribe

I'm interested in the short-term and/or long-term effects of eating fermented dairy products. I would be especially interested to know how kefir (or yogurt) affects the GI tract, the microflora balance, metabolism, weight, etc.

Are any effects long-term - in other words, can, say, 2 servings daily of yogurt or kefir over a month or a year or a decade actually change the composition of one's gut microflora for the better? Can they lead to effects on body weight (as a fecal transplant would)? What about between fermented dairy versus normal dairy (e.g. milk)? I would also be very interested to learn of any actual difference in health effects between ingestion of yogurt versus kefir? Google pulls up lots of woo, and I can't seem to find anything particularly useful in a PubMed skim, but I may be missing stuff in the latter. I'd love to hear anything that anybody here knows, including anecdotal experience of adding it into one's diet.
posted by ClaireBear to Health & Fitness (6 answers total) 9 users marked this as a favorite
 
This is what the science currently says about the longterm benefits and specific health effects of probiotics: ¯\_(ツ)_/¯

Doesn't hurt, sometimes helps.

The idea with probiotics is you're introducing flora that are healthier than what's already there. But the gut flora that you had formed because of the environment (your physiology, what you eat, the pH of your tapwater, whether you exercise, etc), and will tend to go back to that state if you don't also change those things. There's some totally fascinating research going on, but there's a huge number of factors involved.
posted by zennie at 5:06 PM on February 25, 2016 [2 favorites]


I get sinus infections every three or four months like clockwork. I tried drinking yogurt/kefir stuff heavily when I have to start the antibiotics, and I've found that they seemed to reduce the gastrointestinal distress that accompanies the typical gut flora die-off that comes with the heavier-duty antibiotics. Slower onset, less severe overall, etc. Haven't done any kind of serious attempt to discern effects scientifically, even just on myself, though, and it wasn't a cure-all by any stretch.
posted by Scattercat at 8:18 PM on February 25, 2016 [1 favorite]


If I wasn't living it I'd say it was total bunk but our toddler's diaper rash frequency is highly correlated to her yogut (homemade from store bought milk or purchased normal unflavored organic) intake.

It's one of those things where we can see a (non fungal, we know those and resort to the big guns for those) diaper rash flare up, think for a moment and realize that we've been slacking on the yogurt (but not milk as she gets plenty of that either way) then give her some yogurt and the rash fades away without fail (or cream or other changes making much of a difference) within a few diaper changes.
posted by RolandOfEld at 9:07 PM on February 25, 2016


From what I've read, long-term studies haven't been done yet because research into the microbiome is still in its infancy. Have you looked into Justin and Erica Sonnenburg's work? They are scientists at Stanford and doing research on the gut microbiome. There's some educated guessing going on in their book "The Good Gut" but it's a good one to read, as they are the scientists at the forefront of research on the microbiome. Here's an article that Michael Pollan wrote about their work. And another by John Swansburg.

Are any effects long-term - in other words, can, say, 2 servings daily of yogurt or kefir over a month or a year or a decade actually change the composition of one's gut microflora for the better?

In my experience, this happened in days.

Personally, my experience with kefir has completely changed my dietary life. After months of being sick and then diagnosed with IBS, I followed a pretty strict diet for 8 years: cooking mostly from scratch, limiting fats and eating (almost) zero "fast" food and convenience foods. During this time I thought I had an allergy to dairy, so I completely stayed away from it. I'd have a cheat here or there, but only in extreme moderation (literally, a bite). Like others have mentioned, I went through a round of antibiotics for a sinus infection. At the encouragement of my doctor I decided to try probiotics to curb the side effects. Not knowing anything about probiotics or what to buy, I did some research and found a study at Stanford (I can't find it, sorry!) that mentioned IBS symptoms being cleared up among a significant number of people who followed a diet rich in fermented foods. This fascinated me and I figured I had nothing to lose, so I tried it. I ordered kefir grains, fermented them in coconut milk first then got brave and tried cow's milk, and within days I was able to eat all kinds of cheese. Previously, eating a minimal amount of dairy in any form (milk, yoghurt, cheese - brie, cheddar, Parmesan, blue, etc.) would have sent me, er, running for a certain room in the house, STAT. Now, and this is no exaggeration - I can eat Greek yogurt for breakfast, cheese on my salad, and half of a pizza for dinner with zero ill effect. Would I eat that much on any given day? Of course not! It's not healthy! But.... I could. And that is nothing short of amazing given my dietary history. It's as if someone took out my gut and replaced it with Another Extremely Healthy Person's Gut.

As the Sonnenburgs explain in their book, the reason why fermented or "live" foods are so healthy is that they contain microbes which are beneficial to your gut. Plain milk may have lactose, but fermented milk has 30-50 strains of "good gut" bacteria which populate your gut and make the veggies and fruits more bioavailable.

Because of my experience, I admit to having an enthusiasm for kefir that borders on fanaticism. But to go from zero (running for The Room STAT) to sixty "Who ate all the Greek yoghurt?" is just crazy. I never would have believed it six months ago. But it's not a miracle - it's the simple act of me eating 1 cup of kefir a day and keeping my gut happy. But. N=1, YMMV, IANAD, etc. etc. etc. Who knows if it works for everyone. I doubt that I'm a special snowflake, though.

What are the long term effects? Well, now that I can eat dairy, I can easily get my calcium intake each day and I'm (hopefully) staving off osteoporosis and brittle bones, both of which run in my family. Studies have drawn the tentative conclusion that consuming fermented food is related to lack of obesity and supports a healthy immune system. So, there's that.... maybe. No one knows the long-term effects for sure at this point. But I know from my experience that I've never felt healthier.

My money is on the microbiome diet being the new thing that everyone his hearing about. What I like about it is that it seems based in actual studies that point to real conclusions, and haven't originated from a "lose weight fast!" perspective like others.
posted by onecircleaday at 10:06 PM on February 25, 2016 [3 favorites]


Also of interest to you might be prebiotics. Non-digestible fiber is a prebiotic. The theory is that you need prebiotics in order to nourish the bacteria that lives permanently in your gut, because most of them don't.
posted by onecircleaday at 10:16 PM on February 25, 2016


There's at least one reputable study that suggests eating more yogurt will decrease your body weight over the long term:
Yogurt consumption was also associated with
less weight gain in all three cohorts. Potential
mechanisms for these findings are unclear; intriguing
evidence suggests that changes in colonic
bacteria might influence weight gain. It is also
possible that there is an unmeasured confounding
factor that tracks with yogurt consumption
(e.g., people who change their yogurt consumption
may have other weight-influencing behaviors
that were not measured by our instruments).
Summary for general audiences.
The Real Paper -- check out page 9 (pdf numbering) or page 2400 (document numbering) for the source of that quote.
posted by gregr at 9:50 AM on February 26, 2016


« Older Simple email tasking/notifications compatible with...   |   It recently took me 8 hours to run 3 errands Newer »
This thread is closed to new comments.