While both soy and rice milk are good choices if you're trying to limit your intake of animal products or have an allergy or intolerance to cow's milk, they're not necessarily healthy for everyone. Side effects may include allergic reaction, impaired fertility or difficulty maintaining a healthy weight. Further, an additive found in these drinks may be carcinogenic. Consult your doctor to discuss milk options that fit your health and nutritional needs.
An allergic reaction is a potential side effect you may experience from soy or rice milk. If you're drinking soy milk due to an allergy to the protein in cow's milk, there is a chance you may also be allergic to the protein in soy, according to KidsHealth. In general, rice is less allergenic, but allergies are more common in communities that eat a lot of rice, says the Institute of Food Research. Allergy symptoms might include rash, difficulty breathing, nausea, vomiting, abdominal pain or swelling.
Concerns of Phytoestrogens in Soy
Soy milk is a rich source of phytoestrogen, which is the plant form of the estrogen hormone. Phytoestrogens may promote health by reducing menopausal symptoms or preventing osteoporosis. However, getting too much soy in the diet may affect female fertility. Drinking soy milk as a child may also affect brain and reproductive development.
Certain types of soy milk contain added sugar for sweetness. Added sugars, even those promoted as healthy such as cane sugar, provide calories without any nutritional value. The 2010 Dietary Guidelines for Americans suggests limiting your intake of foods with added sugar to help limit calorie intake for weight control. Look for unsweetened soy milk.
Rice milk is naturally sweet and does not usually contain added sugar. However, it's a high-glycemic food, which means it digests quickly and may cause fluctuations in your blood sugar. As a high-GI food, rice milk is not good for hunger control, which may make it harder to manage weight.
Exposure to Carrageenan
Carrageenan is a food additive used to thicken liquids and is found in a number of plant-alternative milks, including brands of soy and rice milk. While food-grade carrageenan is considered safe, the International Agency for Research on Cancer, a unit of the World Health Organization, says degraded carrageenan may be a possible carcinogen in people. Small amounts of degraded carrageenan are found in foods that contain carrageenan, and more is made when the additive hits your stomach, according to the Center for Science in the Public Interest. While the health risk may be small, you may consider choosing brands of soy and rice milk made without the thickener to limit exposure.