Soy milk is the closest nutritional match to cow’s milk and the most well-rounded option for most people. It delivers more protein than any other plant milk, comes with a low glycemic index, and contains less saturated fat than dairy. But the best choice depends on what you’re optimizing for, whether that’s protein, calories, blood sugar, or heart health. Here’s how the major options compare.
How Plant Milks Stack Up Nutritionally
The differences between plant milks are surprisingly large. Per 100 grams (just under half a cup), soy milk provides 3.55 grams of protein, which is actually slightly more than whole cow’s milk at 3.27 grams. Oat milk delivers only 0.8 grams, almond milk 0.66 grams, and coconut milk a mere 0.21 grams. Scale those numbers up to a standard 8-ounce serving and the gap becomes stark: a cup of soy milk gives you roughly 8.5 grams of protein, while a cup of almond milk provides about 1.6 grams.
Calorie counts also vary widely. Almond milk is the lightest at about 46 calories per cup, followed by coconut milk drinks (around 74 calories), soy milk (about 91 calories), and oat milk at roughly 115 calories. If you’re watching your calorie intake, almond milk wins easily, but you’re trading away nearly all the protein to get there.
Soy Milk: The All-Around Winner
Soy milk’s nutritional profile is the reason dietitians consistently rank it first. Its protein content is comparable to cow’s milk, and that protein is complete, meaning it contains all the essential amino acids your body can’t make on its own. No other widely available plant milk can say that.
Soy milk also has a low glycemic index, meaning it raises blood sugar slowly and modestly. This matters if you’re managing diabetes or insulin resistance, or if you simply want steady energy after breakfast. Its fat content is similar to semi-skimmed cow’s milk, with less saturated fat. Most commercial soy milks are fortified with calcium and vitamin D, which closes the remaining gap with dairy. The one real drawback is taste preference: some people find it beany or chalky, especially in coffee.
Soy does contain phytates, compounds that can reduce how well your body absorbs minerals like calcium and magnesium. Soy milks contain roughly 0.8 to 1.33 milligrams of phytate per gram. In practical terms, this means some of the calcium added through fortification may not be fully absorbed. Shaking the carton well before pouring helps, since fortified minerals tend to settle at the bottom.
Oat Milk: Creamy but Higher in Sugar
Oat milk has become the default choice in coffee shops because it froths well and has a naturally sweet, creamy flavor. It’s higher in calories and carbohydrates than most other plant milks, and its glycemic index falls in the medium range. For comparison, dairy milk has a glycemic index of 37, while oat milk sits noticeably higher. Rice and coconut milks are worse still, with glycemic values that can reach into the 90s.
If you have diabetes or are prediabetic, oat milk may not be ideal as an everyday choice, especially in sweetened versions. Its protein content is low at about 1.9 grams per cup, so it won’t do much to keep you full. Where oat milk does shine is in its fiber content, particularly beta-glucan, a soluble fiber linked to lower cholesterol. But the amounts in a single serving of oat milk are modest compared to eating a bowl of oats.
Almond Milk: Low Calorie, Low Everything
Almond milk is essentially flavored water with a small amount of almond content, typically 2 to 3 percent almonds by weight. That makes it extremely low in calories, which is its main selling point. It’s also low in saturated fat, usually around 1 to 2 percent total fat, similar to semi-skimmed cow’s milk but with less saturated fat.
The trade-off is that almond milk provides almost no protein and very little nutrition beyond what’s added through fortification. If you use it as a splash in coffee or cereal, that’s fine. If you’re relying on it as a significant part of your diet, especially for children or older adults who need protein, it falls short. It also has a medium glycemic index, placing it between soy (low) and rice (high).
Coconut Milk: Watch the Saturated Fat
There’s an important distinction between canned coconut milk (used in cooking) and the carton-based coconut milk sold as a dairy alternative. Canned coconut milk contains 16.9 grams of fat per 100 grams, nearly as much as single cream. Even reduced-fat canned versions still pack 7.7 grams of fat per 100 grams, most of it saturated.
The coconut “milk alternative” drinks sold in cartons are much more diluted and nutritionally closer to low-fat milk in terms of calories and total fat. But they’re very low in protein and have a high glycemic index, making them one of the weaker options overall. If you enjoy the taste, treat it as a flavor choice rather than a nutritional one, and look for unsweetened, fortified versions.
What to Look For on the Label
The plant base matters less than what the manufacturer adds or leaves out. Three things to check on the carton:
- Fortification: Look for added calcium (ideally 120 mg per 100 ml, matching cow’s milk) and vitamin D. Vitamin B12 is also important if you’re vegan. Unfortified plant milks are nutritionally empty compared to dairy.
- Added sugar: Sweetened plant milks can contain 10 to 15 grams of sugar per cup. Always choose “unsweetened” versions. Flavored varieties like vanilla almost always contain added sugar.
- Emulsifiers: Many plant milks use carrageenan, an ingredient derived from red seaweed, to improve texture. Lab studies and mouse research suggest carrageenan can promote gut inflammation by disrupting the protective mucus layer in the intestines, potentially allowing gut bacteria to trigger immune responses. The real-world significance in humans is still debated, but if you have inflammatory bowel issues, you may want to choose brands that skip it. Gellan gum and sunflower lecithin are common alternatives.
Plant Milk for Children
Children under 12 months should not receive any plant milk. After 12 months, the CDC recommends whole cow’s milk or fortified dairy alternatives as part of a balanced diet. “Fortified dairy alternatives” is a specific category: the product needs to be nutritionally comparable to cow’s milk in calcium, vitamin D, and ideally protein. Soy milk is the only plant milk that reliably meets all three criteria without supplementation from other foods.
If you’re raising a child on a plant-based diet, relying on almond, oat, or coconut milk as the primary milk source can leave gaps in protein and calorie intake during a period of rapid growth. Soy milk or a pea protein-based milk with fortification is a safer foundation, combined with other protein-rich foods throughout the day.
Matching the Milk to Your Goal
- Highest protein: Soy milk, or pea protein milk (which often hits 8 to 10 grams per cup)
- Lowest calorie: Unsweetened almond milk
- Best for blood sugar: Soy milk (low glycemic index)
- Best for coffee: Oat milk (froths and blends well, neutral-sweet taste)
- Lowest saturated fat: Almond or soy milk
- Best overall nutrition: Fortified soy milk
No single plant milk is perfect, and most people rotate between a couple based on the situation. The important thing is choosing unsweetened, fortified versions and not assuming that any plant milk automatically matches what dairy provides. Soy milk comes closest. Everything else requires more intentional planning to fill the nutritional gaps.