Buttermilk is a fermented dairy product.

Most modern buttermilk is cultured, meaning that beneficial bacteria have been added to it. It’s different from traditional buttermilk, which is rarely found in Western countries today.

This article refers to cultured buttermilk simply as buttermilk.

This dairy product is most often used in baking. For example, it’s a common ingredient in biscuits, muffins, quick breads, and pancakes. It can also be used in batters for fried foods or as a creamy base in soups, potato salad, or salad dressings.

This article reviews the nutrition, benefits, and downsides of buttermilk and tells you how to make substitutes for store-bought varieties.

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The name buttermilk is somewhat misleading, as it doesn’t contain butter.

Traditional buttermilk is the liquid leftover after whole milk has been churned into butter. This type of buttermilk is rarely found in Western countries today but remains common in parts of Nepal, Pakistan, and India.

Buttermilk today consists mostly of water, the milk sugar lactose, and the milk protein casein.

It has been pasteurized and homogenized, and lactic-acid-producing bacteria cultures have been added, which may include Lactococcus lactis or Lactobacillus bulgaricus.

Lactic acid increases the acidity of the buttermilk and prevents unwanted bacterial growth, which extends its shelf life. It also gives buttermilk its slightly sour taste, which is a result of the bacteria fermenting lactose, the primary sugar in milk (1).

Buttermilk is thicker than milk. When the bacteria in the beverage produce lactic acid, the pH level is reduced, and casein, the primary protein in milk, solidifies.

When the pH is reduced, the buttermilk curdles and thickens. This is because a lower pH makes the buttermilk more acidic. The pH scale ranges from 0 to 14, with 0 being the most acidic. Cow’s milk has a pH of 6.7–6.9, compared with 4.4–4.8 for buttermilk.

Summary Modern buttermilk is a cultured, fermented dairy product often used in baking. It contains bacteria that make it sour and thicker than regular milk.

Buttermilk packs a lot of nutrition into a small serving.

One cup (245 ml) of cultured buttermilk provides the following nutrients (2):

  • Calories: 98
  • Protein: 8 grams
  • Carbs: 12 grams
  • Fat: 3 grams
  • Fiber: 0 grams
  • Calcium: 22% of the Daily Value (DV)
  • Sodium: 16% of the DV
  • Riboflavin: 29% of the DV
  • Vitamin B12: 22% of the DV
  • Pantothenic acid: 13% of the DV
Summary One serving of buttermilk is a good source of several nutrients, including protein, calcium, and riboflavin.

Buttermilk may offer several health benefits, including improved blood pressure and bone and oral health.

May be easier to digest than other dairy products

The lactic acid in buttermilk can make its lactose content easier to digest. Lactose is the natural sugar in dairy products.

Many people are lactose intolerant, meaning that they don’t have the enzyme needed to break down this sugar. Approximately 65% of people worldwide develop some degree of lactose intolerance after infancy (3).

Some people with lactose intolerance can drink cultured dairy products with few to no side effects, as the lactose is broken down by the bacteria (4).

May support strong bones

Buttermilk is a good source of calcium and phosphorus, as well as vitamin D if it has been fortified. Full-fat varieties are also rich in vitamin K2 (5, 6).

These nutrients are important for maintaining bone strength and preventing degenerative bone diseases like osteoporosis, but many people don’t get enough of them (7, 8, 9, 10).

A 5-year study in people aged 13–99 observed that those with phosphorus intakes 2–3 times higher than the recommended dietary allowance of 700 mg per day increased their bone mineral density by 2.1% and bone mineral content by 4.2% (8).

Higher intake of phosphorus-rich foods was also associated with higher calcium intake. Eating more calcium and phosphorus was linked to a 45% lower overall risk of osteoporosis among adults with normal blood levels of these two minerals (8).

There is also emerging evidence that vitamin K2 is beneficial for bone health and treating osteoporosis, particularly in combination with vitamin D. Vitamin K2 promotes bone formation and prevents bone breakdown (11, 12).

May improve oral health

Periodontitis is the inflammation of your gums and supporting structures of your teeth. It’s a very common condition and caused by periodontal bacteria.

Fermented dairy products like buttermilk may have anti-inflammatory effects on the skin cells that line your mouth (13).

The intake of calcium from fermented dairy foods has been associated with a significant reduction of periodontitis. Nondairy foods don’t seem to have this effect (14, 15, 16).

This may be particularly helpful for people who have oral inflammation as a result of radiation therapy, chemotherapy, or Crohn’s disease (13, 17).

May help lower your cholesterol levels

In a small 8-week study in 34 adults, consuming 45 grams, or approximately 1/5 cup, of reconstituted buttermilk (buttermilk powder mixed with water) daily reduced total cholesterol and triglycerides by 3% and 10%, respectively, compared with a placebo (18).

Furthermore, participants who began the study with elevated LDL (bad) cholesterol levels noticed a 3% reduction in this type of cholesterol (18).

Sphingolipid compounds in buttermilk may be responsible for this effect by inhibiting the absorption of cholesterol in your gut. Sphingolipids are part of the milk fat globule membrane (MFGM) in buttermilk (18).

Linked to lower blood pressure levels

Some evidence suggests that buttermilk may help lower your blood pressure.

In a study in 34 people with normal blood pressure, consuming buttermilk daily reduced systolic blood pressure (the top number) by 2.6 mm Hg, mean arterial blood pressure by 1.7 mm Hg, and plasma angiotensin-I converting enzyme by 10.9%, compared with a placebo (19).

Mean arterial blood pressure is the average pressure in a person’s arteries during one heartbeat, whereas plasma angiotensin-I converting enzyme helps control blood pressure by regulating fluid volume in your body (19).

Though these results are encouraging, more research is needed.

Summary Buttermilk is a good source of vitamins and minerals that are known to help maintain strong bones. It also contains compounds that may improve oral and heart health.

Buttermilk may also have several downsides related to its salt content and potential to cause allergic reactions in some individuals.

Can be high in sodium

Milk products contain good amounts of sodium, making it important to check the nutrition label if you need to limit your sodium intake.

Consuming a lot of sodium is associated with an increased risk of high blood pressure, especially among individuals who are salt sensitive. High blood pressure is a risk factor for heart disease (20).

For people who are sensitive to dietary salt, high-sodium diets can damage the heart, kidneys, brain, and blood vessels (21).

Low-sodium foods are defined as having 140 mg of sodium or less per serving. In comparison, 1 cup (240 ml) of buttermilk can pack 300–500 mg of this nutrient.

Notably, lower-fat buttermilk often contains even more sodium than higher-fat versions (2, 22).

May cause allergic reactions or digestive issues in some people

Buttermilk contains lactose, a natural sugar to which many people are intolerant.

Although buttermilk appears to be more easily digested by some people with lactose intolerance, many may still be sensitive to its lactose content.

Symptoms of lactose intolerance include upset stomach, diarrhea, and gas.

People who are allergic to milk — rather than intolerant — should not consume buttermilk at all. Milk allergy can cause vomiting, wheezing, hives, upset stomach, and even anaphylaxis in some people (23).

Summary Some buttermilk may be high in salt and contain compounds like lactose, which may be problematic for some people.

If buttermilk isn’t available or you prefer to use something else, there are several substitutions.

Acidified buttermilk

To make acidified buttermilk, you need milk and an acid. When the two are mixed, the milk curdles.

Acidified buttermilk can be made using dairy milk of any fat content. It can also be made with nondairy milk alternatives, such as soy, almond, or cashew milk. Acids like lemon juice, white vinegar, or apple cider vinegar work well.

The ratio is 1 cup (240 ml) of milk to 1 tablespoon (15 ml) of acid. Gently mix the two ingredients and let the mixture sit for 5–10 minutes until it begins to curdle.

Plain yogurt

Like buttermilk, plain yogurt is a fermented dairy product. You can use plain yogurt as a substitute for buttermilk in baking at a 1:1 ratio.

If the recipe calls for 1 cup (240 ml) of buttermilk, you can substitute 1 cup (240 ml) of yogurt.

Cream of tartar

Cream of tartar is a byproduct of wine production. It’s an acid commonly used in baking as a leavening agent. This is because combining cream of tartar and baking soda produces carbon dioxide gas.

Mix 1 cup (240 ml) of milk and 1 3/4 teaspoons (6 grams) of cream of tartar and let it sit for a few minutes.

To prevent the mixture from getting lumpy, mix the cream of tartar with a few tablespoons of milk before adding it to the rest of the milk.

Summary Several substitutions can be made for buttermilk in baking. Many use a combination of an acid and either dairy or nondairy milk.

Buttermilk is a dairy product rich in vitamins and minerals that may offer several benefits for your bones, heart, and oral health.

Still, it may cause issues for those with lactose intolerance or a milk allergy.

If you tolerate dairy, buttermilk is a great and versatile addition to a healthy diet.