Almond milk is a fine alternative for people allergic to cow's and soy milks, Jaffe's Sicherer says, but almonds pose their own allergenicity hazards. Allergies to tree nuts, including almonds, are among the top allergies in the population, affecting 0.2% of children. And although cow's and soy milk allergies are often outgrown, nut allergies are more likely to persist.
In fact, rice milk manufacturers commonly promote their product as safe for people with any of a number of allergies or intolerances -- including cow's milk, soy and nut allergies, as well as lactose and gluten intolerance. (Gluten, found in wheat and other cereal grains, is not present in any of the milks mentioned here.)
Rice milk, like soy and almond milk, is formulated to contain levels of calcium, vitamin A and vitamin D similar to (albeit lower than) those in cow's milk. But it is not a good source of protein, with just 0.67 grams per serving, and often contains more calories than almond or soy milk: about 113 calories per cup. Its vitamin E levels exceed that of cow's, goat's and soy milk but don't compare with that of some almond milks.
One more thing rice milk doesn't have: flavor in need of masking with sweeteners. "It's a very mild-flavored product," Corvus Blue's Shelke says.
Among plant-based milks, hemp milk is unique, and not just because the cannabis plant it's made from poses legal challenges for farmers.
A glass of hemp milk contains the same number of calories as soy milk, one-third to one-half of the protein, but 50% more fat: 5 to 6 grams. However, most of the fats in hemp milk are omega-3 and omega-6 essential fatty acids, key for nervous system function and healthy skin and hair. Certain omega-3 and omega-6 fats also appear to reduce inflammation and lower blood lipid levels.
Plant oils typically have an excess of omega-6 fats relative to omega-3s -- and the hemp seed is no exception. A cup of hemp milk (which is made from the "nut" of the hemp seed but can also contain some of the hull) often provides about 1 gram of omega-3s and 3 to 4 grams of omega-6s. Still, that level of omega-3s is high for plants, making hemp milk a useful source of them -- especially given that American diets typically provide too few omega-3 fats and too many omega-6s.
In fact, some nutrition experts recommend a dietary ratio of omega-3s to omega-6s of between 1:1 and 1:3, a ratio that occurs naturally in hemp milk.
But the story is more complicated than that. It is unclear whether the predominant omega-3 fat in hemp, alpha linolenic acid (ALA), has the same heart-health benefits of those found abundantly in fish oils (known as EPA and DHA for short), says William Harris, director of the Cardiovascular Health Research Center at the University of South Dakota.
Like soy milk, hemp milk is low in saturated fat and cholesterol-free. It's also free of lactose, and allergies to hemp are rare. Christina Volgyesi, vice president of marketing for Portland, Ore.-based Living Harvest Foods, which makes hemp milk, says the milk is made from different cannabis varieties than those used to produce marijuana, and contains none of the mind-altering active ingredient THC.
Hemp milk contains many of the nutrients found in cow's milk (including calcium, vitamin A and vitamin D) since it's fortified. In fact, some brands provide 40% to 50% of the daily recommended allowance of calcium, as compared with the 30% found in cow's milk.
Nutritionally, hemp seeds are similar to flax seeds, which have become increasingly popular sources of essential fatty acids in recent years. But not all seeds rich in the fats lend themselves to a palatable milk alternative.
"Flax milk would probably be dark brown," Shelke says. "We are probably not prepared to drink something dark brown in color."
Unless, of course, it's chocolate milk -- be it of cow's, goat's, soy, almond, rice or even hemp.