I've been doing keto for 14 months with great results. But I recently read that long-term low-carb damages gut microbiome diversity because bacteria need fiber. Is there research on this? Has anyone experienced gut issues after a year+ of keto?
Legitimate concern. Here's what research shows:
Very low carb diets do change microbiome composition — they reduce certain fiber-fermenting bacteria. Whether this "change" equals "damage" is debated.
Practical steps on long-term keto: eat a variety of low-carb vegetables, include fermented foods (kimchi, sauerkraut, full-fat yogurt, kefir), consider a quality probiotic, and don't eliminate vegetables just to minimize carbs.
14 months in, I eat 4-5 different vegetables daily and fermented foods regularly. My digestion has never been better — less bloating, more regularity, no more IBS symptoms I used to have. Anecdotal but I haven't experienced the issues articles describe.
Many people come to keto after years of a carb-heavy Western diet already damaging their microbiome through processed foods and sugar. Going from junk food to keto with vegetables is almost certainly a microbiome improvement even if it's different from a theoretical high-fiber ideal.
I add a tablespoon of inulin powder (a prebiotic fiber, zero net carbs — fiber is not digested) to my morning coffee. It feeds beneficial bacteria without contributing to blood sugar. Jerusalem artichoke powder is another option.