Buttermilk is a nutrient-dense drink that delivers 10 grams of protein and about 350 milligrams of calcium per cup, all for roughly 137 calories. It also contains beneficial bacteria, compounds linked to lower cholesterol, and less lactose than regular milk. For most people, it’s a solidly healthy choice that doesn’t get nearly the attention it deserves.
What’s Actually in a Cup
A single cup (245 grams) of cultured reduced-fat buttermilk provides 137 calories, 10 grams of protein, and about 5 grams of fat. That protein count is comparable to a cup of regular milk, making buttermilk a meaningful source of this nutrient for relatively few calories.
The standout mineral is calcium: one cup supplies roughly 350 milligrams, which is about 27% of the daily recommended intake for most adults. You also get 0.91 micrograms of vitamin B12, a nutrient essential for nerve function and red blood cell production. Because B12 is found almost exclusively in animal products, buttermilk is a useful source for people who eat limited meat.
Traditional vs. Cultured Buttermilk
The buttermilk you find in grocery stores has almost nothing to do with the original version. Traditional buttermilk was simply the thin, slightly tangy liquid left behind after churning cream into butter. It was a byproduct, not a product. As long as people have made butter, this liquid existed, and for centuries it was a refreshing, mildly sour drink consumed on farms.
Starting in the 1920s, commercial dairies began manufacturing what we now call cultured buttermilk. They take low-fat milk and introduce lactic acid bacteria that ferment it under moderate heat, thickening the texture and creating that characteristic tang. This is what lines refrigerator shelves today. Both versions contain beneficial bacteria, but the cultured type is more standardized and widely available. Yogurt has since overtaken buttermilk as the go-to cultured dairy product, even though buttermilk offers many of the same probiotic benefits.
Probiotic Content and Gut Health
Cultured buttermilk is a fermented food, which means it contains live bacteria that can support digestive health. The dominant strains belong to the Lactobacillus family, bacteria that are natural, non-harmful residents of the human intestine. Their presence helps protect the balance of your gut’s microbial community.
Research on strains isolated from traditional buttermilk has identified species like Lacticaseibacillus paracasei and Lacticaseibacillus casei, both recognized for their probiotic potential. In lab testing, these strains showed strong activity against harmful bacteria including E. coli and Staphylococcus aureus. While lab results don’t translate directly to what happens in your gut after drinking a glass, they reinforce that buttermilk’s bacterial profile is genuinely beneficial, not just marketing.
The probiotic content does vary by brand. Some commercial buttermilk is pasteurized after culturing, which kills off live bacteria. If probiotics are your goal, look for labels that mention live or active cultures.
Cholesterol and Blood Pressure
Buttermilk contains a compound that most other dairy products don’t have in significant amounts: milk fat globule membrane, or MFGM. This is a thin layer of fats and proteins that naturally surrounds fat droplets in milk. During butter production, MFGM gets released into the liquid, concentrating it in buttermilk.
A 2024 meta-analysis of randomized controlled trials found that MFGM supplementation significantly reduced both total cholesterol and LDL (the “bad” cholesterol) in healthy adults. Triglycerides and HDL cholesterol were not significantly affected. Separately, clinical research has observed that buttermilk consumption reduced systolic blood pressure and levels of an enzyme involved in blood pressure regulation. These effects are modest, but they suggest buttermilk has cardiovascular benefits beyond what you’d get from drinking plain milk.
Easier to Digest Than Regular Milk
If you have mild lactose sensitivity, buttermilk may be easier on your stomach than a glass of regular milk. A 150-milliliter serving of buttermilk contains about 6 grams of lactose, compared to 7 grams in the same amount of whole cow’s milk. That’s a small difference on paper, but the fermentation process does additional work. The lactic acid bacteria in cultured buttermilk partially break down lactose during production, and they continue to do so in your digestive tract. The result is that many people who experience bloating or discomfort from regular milk tolerate buttermilk without issues.
That said, buttermilk is not lactose-free. If you have severe lactose intolerance, it can still cause digestive symptoms, especially in larger amounts.
Benefits for Skin
Buttermilk’s lactic acid content gives it a secondary reputation as a skincare ingredient. Lactic acid is classified as an alpha hydroxy acid (AHA), a category of compounds widely used in commercial exfoliants. When applied topically, lactic acid loosens the bonds between dead skin cells on the surface, promoting cell turnover and revealing fresher skin underneath. It’s a mild, gentle exfoliator compared to harsher chemical peels.
Traditional home remedies have used buttermilk as a face wash or mask ingredient for this reason. The concentration of lactic acid in buttermilk is lower than what you’d find in a dedicated skincare product, so the effects are subtle. It works best as a gentle, natural complement to a skincare routine rather than a replacement for targeted treatments.
Why Bakers Love It
Beyond drinking, buttermilk plays a specific chemical role in cooking. Its acidity reacts with baking soda (an alkaline compound) to produce carbon dioxide gas. Those tiny bubbles get trapped in batter, giving pancakes, biscuits, and quick breads their light, fluffy texture. Without an acidic ingredient like buttermilk, baking soda can’t do its job as a leavening agent.
The acid also tenderizes gluten in flour, producing a softer crumb. This is why buttermilk pancakes taste noticeably different from those made with plain milk. The tang adds flavor, but the real contribution is structural.
Who Should Be Cautious
Buttermilk is a dairy product, so it’s off the table for anyone with a true milk allergy. The proteins that trigger allergic reactions (casein and whey) are fully present in buttermilk regardless of fermentation. People on sodium-restricted diets should also check labels, as some commercial buttermilk contains added salt. And while the fat content of reduced-fat versions is reasonable at about 5 grams per cup, full-fat varieties will be higher.
For most people, though, buttermilk is a protein-rich, calcium-packed, probiotic-containing food that costs less per serving than yogurt and works in everything from a cold glass to cornbread batter. Its biggest problem isn’t nutrition. It’s that most of us forgot it was in the dairy aisle.