Both are cultured beverages—meaning that probiotic bacteria cultures are added to ferment fresh milk. But the “recipes” differ significantly. For starters, kefir may contain a dozen or more different bacterial strains and yeast cultures; buttermilk typically contains only one probiotic strain: lactic acid bacteria.

Kefir (kuh-FEAR, not KEE-fur) is fermented from whole milk using special kefir grains (more about them in a minute). Buttermilk, more formally called cultured buttermilk, is made by fermenting skim milk with lactic acid bacteria, Streptococcus lactis.

The probiotics enable both beverages to be digested more easily than milk. Both beverages have a yogurt-like tang.

Modern kefir is made in the original (plain) plus fruit flavors, to capitalize on the popularity of yogurt, and some people think that kefir is “drinkable yogurt.” But the kefir grains and a different fermentation process make it a different recipe from yogurt.

Both can be drunk straight and used instead of milk or buttermilk in cooking and baking. Some popular uses:

[1] Buttermilk, a staple in great-grandma’s kitchen. If you need just a cup, see the footnote below for how to make it from whole milk (photo © Wisconsin Milk Marketing Board).

MAKING KEFIR & BUTTERMILK

Cultured buttermilk. Before universal pasteurization, butter was made by letting whole milk stand to allow the cream to separate, rising to the surface; the cream would be skimmed off, leaving “skim milk” below. Natural fermentation would occur, souring the milk slightly.

Today, nonfat (skim) milk is acidified with lactic acid bacteria, which add tartness and cause the formation of more protein. This is why buttermilk is thicker than ordinary milk, and why modern buttermilk, made with added cultures, is called cultured buttermilk.

Kefir. Kefir is made with kefir grains—colonies of bacteria, yeast, proteins and sugars that resemble tiny buds of cauliflower—that ferment the milk. These granules of active cultures are strained from the fermented milk before it is bottled. Here’s more on how kefir is made, and a photo of the grains.

Homemade kefir continues to ferment as it ages. It’s a bit effervescent (bubbly) from the fermentation, where the cultures consume the sugars in the milk and release carbon dioxide. Commercial kefir cuts back on the effervescence.

You can make both kefir and buttermilk at home; but as with many foods, it’s much more convenient to simply buy a bottle or carton. If you want to try your hand at it, here’s a resource.

Drinking buttermilk and kefir can be beneficial to one’s health. The bacteria aid in the digestion of food, and consistent consumption can help to resolve certain intestinal conditions.

Some sources claim that the regular intake of either drink can reduce the risk of colon cancer.

But if you like yogurt in general, and haven’t enjoyed a glass of buttermilk or kefir, pick up one of each and taste them side by side.

And if you’re not going to drink all of it or whip up some smoothies, definitely bake or cook with it.

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*How to make buttermilk. You don’t have to buy a quart of buttermilk when you need a cup or less. You can make 1 cup of buttermilk by adding 2 tablespoons of fresh lemon juice or vinegar to a one-cup measure, plus enough milk to make 1 cup. Stir and let sit. For 1/2 cup, halve the recipe.