Plant "milks" made from nuts, seeds, whole grains and legumes certainly sound nutritious. But according to a new review from McGill University, surprisingly few come close to matching the nutrient content of cow's milk.
The McGill study, published last week in the Journal of Food Science and Technology, pitted four milk alternatives – almond, rice, coconut and soy beverages – against whole cow's milk to find out which one was the most nutritious replacement for dairy.
The conclusion: Soy milk came the closest to matching the nutritional profile of cow's milk, and by a long shot. It had similar amounts of protein, carbohydrate, fat and vitamins and minerals.
A key deciding factor was the higher protein content of soy milk. Brands of soy milk, on average, supplied 8.7 g of protein per one cup, while almond, coconut and rice milks contained anywhere from 0 to 1.6 g per serving. (Cow's milk has 8 g protein per one cup.)
The authors also noted that soy milk contained monounsaturated and polyunsaturated fats, similar to cow's milk. (Almond milk also supplied these two heart healthy fats.)
But is too much soy a bad thing?
No one disputes the fact that soybeans deliver plenty of nutrition, especially protein. But some critics warn that too much soy increases breast cancer risk, interferes with male reproductive health and harms thyroid function.
In fact, there isn't any evidence that consuming soy foods, as part of a healthy diet, increases breast cancer risk. Observational studies suggest that breast cancer survivors who include soy foods in their diet have a lower risk of the cancer returning.
Nor is there evidence to support the claims that soy interferes with male reproductive function – feminization, erectile dysfunction or infertility. Research has found that consuming soy at levels above the typical Asian diet (which is known to be high in soy) has not been shown to affect levels of male sex hormones or sperm quality.
There is concern that eating large amounts of soy can result in an underactive thyroid and goiter (an enlarged thyroid gland) by blocking the production of thyroid hormones. However, this appears to only occur in people who are iodine deficient, a mineral needed for normal thyroid function.
There were other interesting findings from the McGill study: Rice milk has, on average, three times more carbohydrates than cow's milk. Made from milled rice, the beverage is high in carbohydrates (on average, 25 g per cup) compared to other milk alternatives. Coconut beverages are low in calories (on average, 50 per cup) but, unlike the other milks analyzed, most of those calories come from saturated fat.
So, whether you swap your almond or coconut milk for soy milk really depends on your taste preference, the rest of your diet and your personal values (e.g., environmental concerns such as the large volumes of water needed to produce almonds and cashews).
What to look for:
If you use non-dairy milks because you are lactose intolerant, allergic to dairy, vegan or you simply want to eat more plant-based meals, read labels to know what you're getting – and what you're not getting.
Protein: Cow's milk has 8 g of protein per cup, which, among its many other benefits, helps you feel full. Besides soy milk, pea milk also boasts a decent protein content.
A recent newcomer, pea milk is made from yellow peas and contains 8 to 10 g of protein per one cup serving. It also contains more calcium than cow's milk (450 mg versus 310 mg per cup).
Almonds, cashews and hemp seeds are high in protein but their store-bought plant-based milks are not. That's because much of the nut and seed pulp are filtered out of the product, which also explains why many milk alternatives are low in calories. (And why commercial nut milks contain fraction of the vitamin E found in a serving of whole nuts.)
If you opt for a non-dairy milk that's low in protein, be sure to get protein elsewhere in your diet. That's especially important if your diet is completely dairy-free.
Fortified: To get nutritional benefits that are like cow's milk, choose a brand that's fortified with vitamins and minerals. Fortified milk alternatives typically supply 330 mg of calcium, 1 mcg of B12 and 100 IU of vitamin D along with vitamin A, riboflavin and zinc.
Unsweetened: It's not only chocolate and vanilla flavoured non-dairy milks that contain added sugars (two to four teaspoons worth per one cup). Unflavoured (original) versions are made with refined sugars, delivering one to two teaspoons (4 to 8 g sugar) per serving.
Unsweetened milk alternatives are free of added sugars.
Avoid carrageenan: Extracted from red seaweed, carrageenan is used as a thickener and stabilizer in the food industry. Degraded carrageenan (not the type added to foods) has been linked to gut inflammation and colon cancer in animals. Yet, some experts contend that food-grade carrageen may also harm the gut.
Many, but not all, manufacturers have phased out this controversial thickener in plant-based beverages.
Leslie Beck, a Toronto-based private practice dietitian, is Director of Food and Nutrition at Medcan.