If you're lactose intolerant, you don't produce the enzyme lactase. This means that lactose -- the chemical name for milk sugar -- passes undigested into your lower intestine. There, native bacteria break down the lactose, producing large quantities of gas. This leads to symptoms including bloating and cramping. Several alternatives are available to you if you're lactose intolerant, some of which are dairy-based and others of which are not.
Lactose-Free Milk
One of the simplest alternatives to conventional milk, if you're lactose intolerant but enjoy the taste of dairy, is lactose-free milk. This is regular milk that has been mixed with a small amount of the lactase enzyme. The milk is allowed to react with lactase for 24 hours, which "predigests" the lactose. The resulting milk is a bit sweeter than regular milk, due to the breakdown of lactose into sweeter-tasting sugars, but it is perfectly safe for you if you're lactose intolerant.
Yogurt
You can probably eat yogurt made from conventional milk even if you're lactose intolerant. This is because the bacteria that produce yogurt from milk -- the many probiotic strains including Lactobacillus acidophilus -- digest lactose. The bacteria produce a chemical called lactic acid as they break down lactose. Lactic acid reacts with proteins in milk, producing the creamy texture characteristic of yogurt. Most yogurts are nearly lactose-free, making them appropriate alternatives for all but the most sensitive lactose-intolerant individuals.
Soy Milk
One nondairy option is soy milk, which is made by processing soy beans and extracting a mixture of protein and carbohydrate with a white, milky color and texture. Most soy milk isn't as naturally sweet as cow's milk, so generally it has a bit of sugar added to it. You can bake with soy milk -- substitute soy for cow's milk on a one-to-one ratio -- but your baked goods may taste slightly different. Soy milk curdles easily if heated -- this is especially noticeable in coffee and tea -- but this doesn't affect the flavor or the nutritional value.
References
- OrganicMeadow.com: Lactose-Free Milk
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
