DEAR DR. BLONZ: I experience lactose intolerance. You have mentioned how a full meal and its fat content allow for slower passage of the food out of the stomach and through the digestive system. Does this also include lactose and its potential effects for those who are intolerant? I tend to react to a skim milk latte consumed on an empty stomach, but less so if I order it with whole milk instead. I also note little effect from eating yogurt for breakfast or ice cream for dessert. I wonder how fermented dairy products affect lactose intolerance? -- S.T., Walnut Creek, California
DEAR S.T.: Lactose is the main carbohydrate found in milk products. If you have lactose intolerance, the enzyme needed to digest the lactose (lactase) is either absent or available at a less-than-ideal level. With insufficient levels of lactase, lactose, along with the fluid it tends to attract, can make it into the large intestine, becoming a food source for organisms naturally present in our microbiome. Intestinal gas, mostly hydrogen, gets produced, with its uncomfortable pressure and effects. We all tend to produce lactase at birth, but the genetic instruction to keep this enzyme on the job declines during childhood. More on lactose intolerance can be found at b.link/9kzdbmyx.
The presence of fat or protein in a meal slows the rate at which the food exits the stomach and travels through the small intestine on its way to the large intestine. Dietary fiber doesn't get broken down or absorbed in the small intestine, which increases the bulk moving through the digestive tract. Bulk lessens the frequency at which broken-down food components come in contact with the absorptive surface of the GI tract.
A healthy digestive system should absorb all bioavailable nutrients at some point along this path. When a particular substance is part of a mixed meal, travel is paced as larger amounts of substances are processed and waiting their turn at the absorptive portals along the small intestine.
The speed at which the lactose enters the large intestine determines the gas production rate. If it comes rapidly, such as a glass of skim milk on an empty stomach, unwanted effects in the lactose-intolerant individual will be more noticeable. When lactose enters the large intestine in metered amounts as part of -- or after -- a regular meal that includes fat, protein and fiber, any gas produced will be at a slower, less socially intrusive pace.
Fermented dairy products, such as yogurt and kefir, offer an advantage, as their probiotic organisms use lactose as a fuel, leaving less to cause problems for the consumer. They tend to be serving-dependent, so know yourself and what you can tolerate. Lactose-free dairy products and over-the-counter lactase products are available, but are also serving-size dependent.
Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.