Acid reflux occurs when acidic digestive juices leak from the stomach into the esophagus. Its symptoms include heartburn, a sour taste in the mouth and a sore throat. Acid reflux can be treated in a variety of ways, but for people whose reflux is related to cow's milk, soy milk can be a good alternative. Understanding why soy and other plant-based milks might be better may help you make choices that could improve your acid reflux symptoms.
Cow's Milk and Acid Reflux
Although everyone reacts differently to certain foods, cow’s milk has long been associated with acid reflux. Babies and young children, who are prone to acid reflux due to the position of their esophagus relative to the stomach, may have a sensitivity or allergy to cow's milk. Infants with an allergy to cow's milk can have the same symptoms as the chronic form of acid reflux known as GERD, or gastroesophageal reflux disease -- such as vomiting, feeding problems and irritability. In a September 2011 study in "Gut and Liver," these symptoms improved when cow's milk was eliminated from the diet. There have been no studies of soy formulas for infants with cow's milk-associated GERD. However, according to the October 2008 "BMJ Clinical Evidence," soy-based formula with added fiber may reduce the frequency of regurgitation in babies aged 7 to 28 days compared with babies fed cow’s milk formulas. Soy-based formula contains small amounts of naturally occurring chemicals called phytoestrogens, which mimic the effects of the female hormone estrogen. At low doses their long-term effect on babies is still unknown.
Cow's milk may also affect acid reflux in adults. While cow's milk allergy is much less common, lactose intolerance -- trouble digesting the milk sugar lactose -- can cause symptoms of nausea and bloating, and it may improve after switching to soy milk.
Fat, Soy Milk and Reflux
If you suffer from acid reflux, you probably know that fatty foods are likely to spark symptoms. One of the reasons cow's milk may trigger acid reflux is its fat content. Fat slows digestion, which can cause undigested food to back up in the gastrointestinal tract. This puts pressure on the band of muscle that keeps the top of the stomach shut, making reflux more likely. One of the advantages of soy milk is that it contains just half the fat of whole milk. According to the Soy Foods Association of North America, 1 cup of whole soy milk has 4 g of fat, while 1 cup of whole dairy milk has 8 g of fat.
Soy Milk Is Alkaline
A big part of managing acid reflux is avoiding acid itself. Stomach acid not only further irritates inflamed esophageal tissue on contact -- it activates the stomach enzyme pepsin, which ends up creating more acid. Soy milk is not at all acidic, and with a pH -- the measure of substance on the spectrum from acid to base -- of 7.94, it may even help neutralize acid in the stomach and the esophagus.
Other Milk Alternatives
In his book "Killing Me Softly From Inside: the Mysteries and Dangers of Acid Reflux," GERD specialist Dr. Jonathan Aviv recommends, in addition to soy milk, other plant-based milks made from almonds, cashews and rice that also have high pH values and are naturally low in fat.
Medical advisor: Jonathan E. Aviv, M.D., FACS