Although you can do a dietary trial to see if symptoms improve with avoidance of dairy, many patients prefer a more objective test. There is a breath test for lactose intolerance that has a sensitivity of 78% and a specificity of 98% (meaning that it may not pick up everyone but if your test is positive, you can consider yourself a lactard). The sensitivity improves if the test measures methane in addition to hydrogen. First, check which labs around you have the lactose breath or the tolerance test. Then check your insurance to see which labs are in network. For the breath test, you have to fast for 12 hours prior to doing the test. In general, you have to be off of antibiotics for 2-4 weeks, and off of laxatives, stool softeners, fiber supplements and acid reducing medications for 2 weeks. A 50 g dose of lactose is given in adults and the hydrogen (and possibly methane) gas is measured in the breath at baseline and every 30 minutes for 3 hours…fun! A rise in hydrogen concentration that is > 20 ppm from baseline is considered positive. Exercise and smoking can cause you to breath faster which can affect the results and should be avoided 2 hours prior to the test. The hydrogen peak is usually seen 1.5 to 2 hrs following lactose ingestion. A false negative can be seen in patients with small intestinal bacterial overgrowth (have an early peak), lung disease, or if you have recently taken antibiotics. There is also a lactose tolerance test that measures serial glucose levels at baseline and every 30 minutes up to 120 minutes post ingestion of a lactose load.
So what foods should you avoid?
Milk (even skim), buttermilk, evaporated milk and sweetened condensed milk contain the most amount of lactose. Ice cream contains a higher lactose load, but some people are able to tolerate this due to the high fat content which decreases the how fast food enters the colon. Cheeses contain lower levels of lactose than milk or ice cream. Hard or aged cheeses are easier to digest than soft cheeses such as brie or mozzarella.
What about Friday night pizza?
There are three enzyme replacements available: Lactaid and Lactrase. Complete dietary restriction is not usually required. Some people can tolerate up to 2 cups of milk in divided doses with meals. However, your spouse will thank you if you avoid that glass of milk before bedtime. You can always try Lactaid milk and other Lactaid products which contain lactase.
So, how do you get your calcium and vitamin D? It is recommended to have 3 servings of dairy per day. The amount of Calcium you need varies based on age and gender. Remember, that you may be able to tolerate some dairy. Live culture yogurt (containing endogenous beta-galactosidase) is often tolerated, whereas yogurts that add milk back after fermentation may produce symptoms. As we discussed, you can consider Lactaid milk or similar products. Some products are even fortified with Calcium, thus you may not have to consume large amounts to get your total recommended daily intake. Other foods high in Calcium include eggs, spinach, leafy greens, broccoli, sardines, soybeans, okra, etc. Calcium and vitamin D supplementation should be discussed with your physician.
Hammer, H., & Hogenauer, C. (2018). Lactose intolerance: Clinical manifestations, diagnosis, and management. In L.S. Friedman (ed.), UpToDate. Retrieved February 19, 2019, from
https://www.uptodate.com/contents/lactose-intolerance-clinical-manifestations-diagnosis-and-management
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