What Is the Difference Between Buttermilk and Milk?

Milk and buttermilk are made from the milk of dairy cows. The milk you drink is pasteurized to kill any potential pathogens and homogenized to prevent the fat molecules from separating, so it’s safe and pleasant to drink. 

Traditional buttermilk is the liquid by-product of churning butter, but today, the buttermilk you buy from the grocery store is milk that’s been fermented by lactic acid bacteria, which gives it a distinctly tangy flavor and creamier texture. To make buttermilk at home, just mix a cup of milk with a tablespoon of lemon juice or white vinegar and let it sit at room temperature for a few minutes. The lemon juice acts as an acid, helping to culture the milk, quickly creating buttermilk that can be used for baking. 

Here are some of the major differences between milk and buttermilk:

Taste and Texture

Milk is mild, slightly sweet, and, depending on the fat percentage you drink, has a creamy texture that seems thicker the more fat content the milk has. While you can drink a glass of buttermilk just as you would milk, it won’t be as pleasant unless you enjoy the sharper flavor. Since buttermilk is fermented, it has a tangy, almost sour cream or plain yogurt-like taste and a thicker texture than whole milk, even though it’s often made from low-fat milk. 

Uses

Milk can be enjoyed on its own as a beverage or added to baked goods, sauces, desserts, or soups, adding more richness and flavor than water. The acidity in buttermilk makes it perfect for marinating meat, adding tenderness to foods like biscuits or pancakes, or acting as a leavening agent in baked goods when it reacts with baking soda or baking powder. 

Nutrition

The nutrition values of low-fat cultured buttermilk and low-fat (1%) milk are very similar. Both have around 100 calories, are high in protein, and provide similar amounts of carbohydrates, fats, and calcium. 

Health benefits

Since milk and buttermilk have similar nutrient profiles, they both provide valuable nutrients like protein, calcium, vitamin A, and, if fortified, vitamin D. Since buttermilk is fermented, it has a few additional health benefits that aren’t found in milk.

Since buttermilk is fermented, it is full of naturally occurring probiotics, which help promote a healthy gut microbiome, aid digestion, support the immune system, and even impact mood and blood sugar, making it a suitable choice for people with diabetes. Since the sugars in buttermilk have been fermented, it could potentially be better tolerated by people with lactose intolerance. However, research hasn’t found its effect on lactose digestion and tolerance to be significant. The lactic acid produced from the fermentation of lactose may also help reduce oral inflammation; some research has found it may alleviate symptoms of acid reflux by lining the esophagus and stomach.^{1, 2, 3, 4, 5}

Price

Ounce for ounce, buttermilk is more expensive than milk. At one supermarket, a half gallon of store-branded buttermilk is $3.50, while the same size of low-fat milk is just $1.99. 

Which One Is Better: Buttermilk or Milk?

Nutritionally, buttermilk and milk are similar, and as long as you choose low-fat varieties of each, it’s hard to compare. Considering the added probiotic and fermentation benefits of buttermilk, it may have a slight edge over milk. But if you’re on a low-sodium diet, you may want to stick with milk, which has significantly less sodium than buttermilk.

When you want a pleasant, mild, and sweet taste, use milk. However, if you want to tenderize meat, add a soft, crumby texture to baked goods, or enhance the effect of baking soda, buttermilk may be the better option. 

Nutrition

The exact nutrition of milk and buttermilk can vary by brand, so make sure to check​​ the nutrition label for the exact nutrition in the product you choose. Cup for cup, low-fat buttermilk​​ , and low-fat milk both have around 100 calories, eight grams of protein, and 12 grams of carbohydrates, making them both good options for weight management.  

Here are the nutrition facts for just a few key nutrients in one cup of low-fat buttermilk and one cup of low-fat milk: ^{6, 7}

Glycemic Index

Both milk and buttermilk are low-GI foods, meaning they have a smaller impact on your blood sugar than many other foods. Milk has a glycemic index typically between 20 and 40, depending on the type of milk. The GI of buttermilk has not yet been scientifically calculated but can be estimated to be close to that of milk, as the protein, fat, carbohydrates, fiber, and sugar content are similar.⁸ 

Vitamins

Both milk and buttermilk are good sources of some B vitamins, like vitamin B12, although milk provides significantly more. Some brands of milk may be fortified with vitamins A and D. In the case of the milk and buttermilk featured, the milk is fortified while the buttermilk is not. 

Minerals

Both milk and buttermilk are excellent sources of calcium, with milk having just slightly more than buttermilk. Milk is a better source of phosphorus, zinc, and magnesium, while buttermilk is a richer source of iron and sodium. 

‍