Lactose intolerance is among the most commonly misunderstood conditions in the field of nutrition, despite a high prevalence (10-15% of the American population). The first point to understand is that lactose intolerance is different than a dairy allergy in a number of ways. The reactions to lactose intolerance are digestive, while an allergic reaction can be more severe and possibly anaphylactic. While those with a dairy allergy must avoid all dairy products, understanding what lactose is and how it works can allow those with an intolerance to enjoy some amounts of certain dairy foods.
Lactose is a naturally-occurring sugar in dairy products, but the amount of lactose varies depending on the type of food. Milk, ice cream, and some yogurts tend to be higher in lactose, while most cheeses, Greek yogurt, sour cream, and cottage cheese have much less. The amount matters, because lactose intolerance is not an all-or-nothing condition; most people who are lactose-intolerant can tolerate low levels of lactose.
This is because lactose intolerance is caused by an absence of the lactase enzyme. Our bodies need lactase to digest lactose. Some people produce less lactase than others, while others produce virtually none at all. If there’s not enough lactase to digest lactose in the diet, undigested lactose reaches the colon where bacteria ferment it and cause excessive gas, abdominal pain, and diarrhea – the symptoms of lactose intolerance.
Lactase supplements – usually a capsule or tablet – can help make up the difference and can be taken with dairy foods to prevent these symptoms.
Certain populations are more likely to be intolerant of lactose than others. Those of African, Asian, or Hispanic descent have much higher rates of lactose intolerance than those of European descent. This is due to a much later introduction of cow’s and goat’s milk in the ancestral diets of those parts of the world. Infants of all genetic backgrounds, however, tend to produce adequate lactase to allow for digestion of breastmilk without issue.
Lactose intolerance can also occur due to a prolonged lack of lactose and dairy consumption. With a prolonged avoidance of these foods, the body reduces its lactase production. This often happens in restrictive eating disorders such as anorexia. In these cases, lactose can usually be gradually re-introduced to the diet and lactase production will follow suit. In other words, self-induced lactose intolerance can usually be reversed. This is less true of those with a genetic predisposition to lactose intolerance.
Dairy alternatives are commonly used in place of dairy foods for those with lactose intolerance. Generally speaking, soy products such as soy milk are the best nutritional equivalent to dairy due to their protein content.
It’s important to know that without dairy in the diet, it may be difficult to meet needs for nutrients like calcium and vitamin D. If you avoid dairy due to lactose intolerance or a dairy allergy, it may be useful to consult with a dietitian to ensure you’re meeting your nutritional needs in these areas.