By Benjamin Bikman, PhD

Apple cider vinegar, sourdough, kefir, and kimchi are some of the most beneficial fermented foods available.

Modern conveniences are a blessing in most every way, but, oddly, refrigeration may have yielded unintended consequences on how we digest and ultimately metabolize the foods we eat.

Before we could store foods at 39°F to prevent them from going bad, many foods and drinks were, deliberately or not, fermented. 

Fermentation involves bacteria digesting sugars (eg, fructose, lactose, glucose) and producing acids (giving a slightly tart taste), carbon dioxide (giving a drink some bubbles or food some air pockets), and, possibly, alcohol (ranging from trace amounts to high, depending on the nature and length of ferment). 

The chemical products are interesting, but it’s what’s lost, not gained, during fermentation that may be particularly relevant in exploring the foods’ insulin-sensitizing benefits. When bacteria are fermenting a food, such as a grain, they’re not eating the small amounts of fat or protein but rather the starches; bacteria eat glucose. Thus, by eating the starches in the fermenting food, the bacteria help us by lowering the amount of sugar we consume, thereby lowering the effects of the food on blood glucose and insulin. 

Top 4 Fermented Foods

So, we have two pronounced insulin-sensitizing benefits when we consume fermented foods: we consume less starch than the nonfermented version, and we ingest beneficial bacteria that can act as probiotics in our intestines.

Apple Cider Vinegar

Raw apple cider vinegar is a surprisingly effective fermented food. Studies have found that consuming just a tablespoon or so of apple cider vinegar with a starchy meal helps lower the glucose and insulin effect of that meal in insulin-resistant people and may help generally improve glucose control for type 2 diabetes.^{1 2} Also, taking two tablespoons of raw apple cider vinegar in the evening helps control glucose levels the following morning, when glucose levels tend to climb.³ (This is why I recommend taking two tablespoons of apple cider vinegar in a full glass of water every morning and evening.)

Sourdough

Sourdough, in which natural bacteria allow the bread to rise over time and in the absence of the ubiquitous “fast-acting” yeast, is another remnant of fermented foods in the West. People with insulin resistance who replace standard bread with sourdough enjoy a significant lowering of blood glucose and insulin levels.⁴ Moreover, sourdough breads have a significantly lower effect on blood glucose compared with normal bread, even when made of the same grains.⁵

If you’re in the market for sourdough bread, pay close attention: many are fake. Most “sourdough” breads in your supermarket are actually standard bread with vinegar added to mimic the tart flavor. True sourdough bread, rarely sold in supermarkets, will mention “sourdough starter” among the ingredients; it’s usually sold in specialty or health food shops.

Kefir

Though yogurt has somewhat remained a part of our diet, fermented milk or “sour milk” (note: not the same as spoiled milk!) as an ingredient is now almost entirely absent, though commercial varieties of kefir are beginning to make a comeback. 

As in sourdough, yogurt bacteria selectively eat the lactose (milk sugar) from the milk, leaving the milk fats and proteins for us. Interestingly, these soured milk products also convey demonstrable protection against insulin resistance: they not only lower the glucose and insulin burden of grains and other foods when consumed with a meal but also improve long-term glucose control.^{6 7}

Kimchi

In contrast to the West, Eastern cuisine has maintained a healthier appreciation for fermented foods. Perhaps the most notable is kimchi—a mix of fermented vegetables. Sure enough, eating kimchi helps lower glucose and insulin levels in people with insulin resistance.⁸ Further, this study compared the effects of fresh kimchi against 10-day-old kimchi, suggesting that it wasn’t the vegetables that were important, but rather what had happened to them while fermenting. 

Similar benefits may be seen with fermented ginseng and soybeans.⁹ But eating fermented foods isn’t the only way to benefit from the work of beneficial bacteria; probiotics also may do the trick. Probiotics are bacteria you ingest that improve your health, usually in the form of a capsule or powder (if not part of a fermented food). Evidence supports the insulin-sensitizing effects of probiotics; much of this is summed up in a meta-analysis that compiled the findings of 17 randomized trials, concluding that probiotics effectively lower fasting glucose and insulin.¹⁰

—

Benjamin Bikman earned his PhD in Bioenergetics and was a postdoctoral fellow with the Duke-National University of Singapore in metabolic disorders. Currently, his professional focus as a scientist and professor (Brigham Young University) is to better understand the role of elevated insulin and nutrient metabolism in regulating obesity, diabetes, and dementia.

Well Being Journal adapted the above excerpt from Why We Get Sick by Benjamin Bikman. Reprinted with permission from BenBella Books.

References available at the following web address.