Oat vs. dairy milk: Nutrition, benefits, and downsides

With its mild flavor and creamy texture, oat milk has become one of the most popular plant-based milks in recent years. But how does it stack up against regular cow’s milk? Here’s what to consider before buying a carton of oat milk or requesting it for your routine coffee order.

Is oat milk healthier than cow’s milk?

“If you have a true milk allergy — an abnormal, potentially serious immune system reaction to the proteins found in cow’s milk — oat milk is a healthier alternative to regular milk,” says Lauren Abeles, a registered dietitian at Harvard-affiliated Brigham and Women’s Faulkner Hospital. Oat milk is also free from other common allergens, such as soy and nuts, which are other common foods used to make plant-based milks.

For people who are vegan (that is, they strictly avoid all animal-based products), oat milk is one good option. But it’s not necessarily healthier than other plant-based milks, says Abeles. Soy milk, for example, contains 7 grams of protein per cup — nearly as much protein as cow’s milk and more than twice as much as oat milk.

Some people have trouble digesting a natural sugar in cow’s milk called lactose. People with this problem (known as lactose intolerance) can experience diarrhea, bloating, or gas after consuming dairy products. Oat and other plant-based milks don’t contain lactose. However, people who are sensitive to lactose can also opt for lactose-free milk, which may be preferable for either taste or nutrition reasons, says Abeles.

How do oat milk and cow’s milk compare nutritionally?

In addition to having less protein than dairy milk, oat milk contains more carbohydrates (see “Nutrients in cow’s milk vs. oat milk”). While the total fat levels are similar, cow’s milk has more saturated fat. Oat milk contains a small amount of fiber, while cow’s milk has none. Most oat milks are fortified with calcium and vitamin D at levels similar to those found in cow’s milk. But there are no set standards and the amounts can vary between brands, so check the label.

Your personal health and dietary needs can affect which milk makes the most sense for you. “If you’re trying to lose weight, you’re better off eating more protein and fewer carbs, so cow’s milk may be a better choice,” says Abeles. That’s also true for people with diabetes or prediabetes, since the carbs in oat milk can contribute to blood sugar elevations, she adds. Compared to cow’s milk, the per serving difference in carbs from oat milk may not seem that large. But the total amount adds up if you put oat milk in your cereal and coffee and use it for cooking, Abeles points out.

Of course, if you have several servings of 2% cow’s milk daily, the saturated fat adds up, too. According to the American Heart Association, people who need to lower their LDL cholesterol should limit their total daily saturated intake to 6% of their total daily calories, which translates to about 13 grams or less.

How can you choose a healthy oat milk?

When shopping for oat milk, read the nutrition label: a brand with a short list of ingredients is usually the healthiest option.

Some brands contain only organically grown oats, water, and sea salt. Others include additives that some people may want to avoid. They include

• added sugars or flavorings (like vanilla or cocoa) to enhance the flavor
• oils (such as canola or sunflower oil) to improve the texture and mouthfeel
• emulsifiers and stabilizers, such as xanthan gum, dipotassium phosphate, and soy lecithin, which help prevent the ingredients from separating and extend the product’s shelf life.

If you have celiac disease or non-celiac gluten sensitivity, make sure to look for a brand that is certified gluten free. Gluten-free oat milk is made from oats that are specially harvested, processed, and tested to prevent contamination with wheat, barley, or rye.

“Drinking milk, whether it’s dairy or plant-based, is a great source of nutrients and hydration. So it’s best to choose one that you like and will drink often,” says Abeles.

*nutrient amounts based on cow’s milk fortified with vitamin D
**nutrient amounts based on oat milk fortified with calcium and vitamin D

Image: © alvarez/Getty Images