Milk and lactose intolerance

If you suffer from lactose intolerance, you are not alone. In fact, it is estimated that 70% of adults are lactose intolerant to some degree. Exemplified as an inability to digest the natural sugar found in dairy foods, lactose intolerance affects both men and women equally, though certain ethnic groups (e.g., Asian, Hispanics) and those with existing medical conditions (e.g., people born prematurely) are affected more frequently.

Being lactose intolerant is not the same thing as having a milk allergy. Milk allergy occurs when a person's immune system reacts to one or more milk proteins. Unlike lactose intolerance, a milk allergy can be life threatening and is usually diagnosed within the first year of a person's life.

Lactose, the natural sugar found in dairy, is a disaccharide sugar - meaning that it is formed by the bonding of the 2 simple sugars: glucose and galactose. Ordinarily the body produces an enzyme called lactase, which breaks the bond so that the 2 simple sugars can be absorbed into the bloodstream and metabolized. People who are lactose intolerant are unable to produce this enzyme, resulting in lactose remaining in the gut. This can lead to a variety of effects, including abdominal pain, diarrhea, flatulence, and bloating.

There are three different classifications for those who are lactose intolerant:

  • Primary lactose intolerance is environmentally induced and arises in societies that do not typically consume dairy. While lactase production decreases for most individuals as they age, the decrease is often most dramatic in infants that are weaned in populations that do not regularly include dairy in their diet. These individuals can lose up to 90% of their ability to produce lactase during their first 4 years of life. As a result of a traditional non-dairy diet, it is speculated that almost all Asian and Native American populations are lactose intolerant.
  • Secondary lactose intolerance is also environmentally induced and is a consequence of certain gastrointestinal disorders. At times, secondary lactose intolerance may temporarily result from exposure to intestinal parasites or arise in sufferers of irritable bowel syndrome (IBS), Crohn's disease, or celiac disease.
  • Congenital lactose deficiency, the third and final classification, is a genetic disorder present at birth that prevents individuals from producing lactase.

Doctors are able to diagnose lactose intolerance through a blood, breath, or stool test. You can also get a good idea of whether or not you are lactose intolerant simply by cutting out lactose from your diet for 1 to 2 weeks and seeing if your symptoms resolve. It is not considered a serious disease and often requires no treatment beyond the use of over-the-counter pills and drops that contain lactase.

Lactose intolerance is a very manageable condition and those that suffer from it do not need to avoid dairy altogether. They can still enjoy smaller quantities of low-fat or fat-free milk, or consume milk products in combination with other foods. Sour cream, yogurt, and ice cream may also be included in the diet, as lactase may already be present due to the bacteria used to produce these foods. Hard cheese and cottage cheese also contain smaller quantities of lactose. There are also low-lactose and lactose-free products in the market that can replace traditional dairy items.

If you are lactose intolerant, you should also consider that lactose is often used as a food additive and may be present in some boxed, canned, frozen, and prepared foods like bread, cereal, lunchmeats, salad dressings, cake and cookie mixes, and coffee creamer.

People with lactose intolerance should also make sure that each day's diet includes enough calcium - a mineral that is traditionally associated with dairy products. Calcium is essential for the growth and repair of bones and a deficiency may lead to osteoporosis. Depending on your age and medical history, you may need anywhere from 200 mg to 1200 mg of calcium per day.

Non-dairy sources of calcium include dark green vegetables such as broccoli, or fish with edible bones such as salmon and sardines. Since milk is also a source of vitamin D, ensure you find a supplement that provides enough vitamin D for your needs (usually between 400 IU and 800 IU per day).

More of a nuisance than a nightmare, living with lactose intolerance is easily manageable with the appropriate considerations. A carefully chosen diet that is supplemented with calcium when needed, or with lactase-containing pills and drops, is the answer to minimizing symptoms.

Brennan Robertson, Hon. BSc (Nutrition)