Cultured Buttermilk: Nutrients, What Research Shows and Safety

Cultured buttermilk is milk that has been fermented with lactic acid bacteria until it is tangy and thick. The USDA entries used on this page are low-fat and reduced-fat cultured buttermilk. [1] The word "buttermilk" can also mean the sour liquid left over from traditional household butter-making, which is thinner and has low total solids. [6] The two are not the same product, and the studies below do not always say which one they used. This page is about the food, not supplements, and it separates what research found from hype.

Read this first

• Not the same as supplements or "buttermilk powder." Some studies test purified milk fat globule membrane (MFGM) ingredients in capsules or powders, which differ from a glass of buttermilk. [3]
• Evidence in one line: the best-known "benefits" come from small or observational studies, and the one trial analysis we read found no clear lipid-lowering effect. [2] [4] [5]
• It is milk. Cultured buttermilk is not safe for cow's milk allergy. For trouble breathing or swelling of the face, lips or throat, call 911 (or your local emergency number). [12]
• Pregnancy: choose pasteurized products. The NHS says to avoid unpasteurized milk and other dairy. [10]
• Sodium is about 363 mg in 1 cup of the low-fat USDA entry (16% of the Daily Value). [1]

What is in it (USDA values)

The values below are for fluid, cultured, low-fat buttermilk (USDA FoodData Central item 170874, SR Legacy). [1] The serving column is the USDA household portion of 1 cup, 245 g. The serving figures are the 100 g values multiplied by 2.45.

% Daily Value uses the FDA 2016 Daily Values; values vary with the brand, fat level and added salt. The reduced-fat entry (FDC 167697) lists 56 kcal, 2.0 g of fat and 105 mg of sodium per 100 g. [1] USDA lists no fiber (0 g). The sugars are the total sugars USDA lists; lactose is not listed separately.

The research interest in buttermilk is mostly about milk fat globule membrane (MFGM), the thin layer around fat droplets that holds polar lipids. Those are lab-measured components. A 2026 meta-analysis in adults tested MFGM and polar lipid ingredients at 19.8 to 5,000 mg a day, but we found nothing in the sources we read saying how much a cup of buttermilk supplies. [3]

What research says

A 2025 systematic review of fermented dairy and blood lipids judged the overall evidence insufficient: most controlled trials showed no significant change, with a few modest reductions, mostly with yogurt and kefir. [13] That review is about fermented dairy as a group.

Eaten as food vs taken as an ingredient. The cholesterol meta-analysis tested purified MFGM ingredients, [3] while the trials above used drinks. Do not assume a glass of buttermilk gives the same result as a capsule.

How much is a normal serving

The USDA household portion is 1 cup (245 g), which has about 98 kcal in the low-fat entry. [1] That is information from the USDA data, not a prescription. We could not open the MyPlate dairy page, so we do not quote its cup-equivalent rule. The FDA says the 2020-2025 Dietary Guidelines advise people 14 and older to keep sodium to 2,300 mg a day. [9] Cooking and baking with buttermilk adds its salt and calories to the dish; we did not read a source on how baking changes its nutrients.

Safety, allergy and medicines

• Milk allergy. Cow's milk is one of the most common food allergens. A milk allergy is an immune reaction and can cause anaphylaxis; call 911 for trouble breathing, throat swelling or fainting. [12] Fermentation does not make milk safe for allergy; one review found limited, weak evidence that some fermented foods lower allergenicity. [14]
• Lactose. NIDDK says many people with lactose intolerance can handle about 12 g of lactose at a time, and that yogurt and hard cheeses are easier than other dairy foods. [8] USDA lists 13.1 g of total sugars in a cup of buttermilk, but not lactose alone. [1] Buttermilk is not named in the NIDDK page, so start small if you are intolerant.
• Pregnancy. The NHS says to avoid unpasteurized milk, yogurt and other dairy and that supermarket products are mostly pasteurized. [10] The CDC says raw milk can carry Listeria, Salmonella and E. coli, with higher risk for children under 5, adults over 65, pregnant women and people with weakened immune systems. [11] Traditional household buttermilk made from raw milk would carry the same risk; check labels.
• Sodium. Some people on low-sodium plans need to count the 363 mg in a cup. [1] WHO advises adults to keep salt under 5 g a day (2 g sodium). [15]
• Weakened immune system. NCCIH says harm from probiotics is more likely in people with severe illness or weakened immunity; it does not discuss buttermilk. [16] Ask a clinician about live-culture foods.
• Medicines. We did not find a buttermilk-specific medicine interaction in the sources we read. A pharmacist can check; see foods and medicine interactions.
• Children. We did not read a source on buttermilk for young children; see foods for babies and toddlers.

Choosing, storing and food safety

• Look for "pasteurized" on the label, especially in pregnancy. [10] [11]
• Compare labels: sodium and fat vary (USDA low-fat 148 mg of sodium per 100 g versus 105 mg in the reduced-fat entry). [1]
• We did not read a source on storage times or on making buttermilk at home; see fermented foods safety and home fermentation risks.

Related pages

• Cow's milk
• Yogurt
• Kefir
• Lassi and ayran
• Food allergy basics and emergency signs
• Foods in pregnancy: what official bodies advise