Lactose Intolerance

Sanisa Foungthong March 19, 2016

What is it?

I have studied this specific genetic disease, and I found out that lactose intolerance is a condition in which people have digestive symptoms such as bloating, diarrhea, and gas after eating or drinking milk products. The lactase protein enzyme that digests lactose and turns it into glucose. Lactase deficiency leads to lactose intolerance. Lactase is a sugar found in milk and milk products. The small intestine produces low levels of lactase and cannot digest much lactose. There are no "cures" but you can prevent the symptoms by avoiding milk products.

Types of Lactose Intolerance

Primary lactose intolerance:
  • most common
  • a person starts life producing plenty of lactase, but lactase production decreases making lactose difficult to digest in adulthood
  • genetically determined

Secondary lactose intolerance:

  • small intestine decreases lactase production after illness, injury, or surgery involving small intestine
  • treatment may restore lactase levels and improve signs and symptoms

Congenital lactose intolerance:

  • babies are born with lactose intolerance caused by absence of lactase
  • the infants have watery diarrhea if they ingest lactose
  • passes from generation to generation called autosomal recessive (both mother and father must pass the same gene for child to develop this type)

Signs and Symptoms

  • abdominal bloating, a feeling of fullness or swelling in the abdomen
  • abdominal pain
  • diarrhea
  • gas
  • nausea


Family History: A health care provider will take a medical, family, and diet history to see if you have lactose intolerance. They look at any symptoms, but basing a diagnosis on symptoms alone may be misleading because digestive symptoms can occur for many reasons other than lactose intolerance.

Physical Exam: During a physical exam, a health care provider usually

  • checks for abdominal bloating
  • uses a stethoscope to listen to sounds within the abdomen
  • taps on the abdomen to check for tenderness or pain

A health care provider may recommend eliminating all milk and milk products from your diet for a short period to see if the symptoms will go away. Symptoms that go away when a person eliminates lactose from his or her diet may confirm he or she has lactose intolerance.

Hydrogen breath test: This test measures the amount of hydrogen in a person’s breath. Normally, a small amount of hydrogen is detectable in the breath when a person eats or drinks and digests lactose.Undigested lactose produces high levels of hydrogen. The test has a patient drink a known amount of lactose, then the patient breathes into a balloon-type container that measures breath hydrogen level.

Stool acidity test: Undigested lactose creates lactic acid and other fatty acids. A child may have glucose in his or her stool as a result of undigested lactose. The health care provider will give the child’s parent or caretaker a container for collecting the stool specimen. The stool sample is given to the health care provider who takes it to a lab for analysis.

I did not find any ethical implications for this disease.

How common is it?

  • 30 to 50 million people in the United States are lactose intolerant
  • In infancy, lactose intolerance results from congenital lactase deficiency. It is rare, with an estimated 1 in 60,000 newborns affected (in Finland)
  • 33% of the human population is lactose intolerant
  • 65% of the human population has a harder time digesting lactose after infancy
  • Occurrs mainly in people of East Asian descent, affecting 90% of adults
  • Only 5% of people of Northern European descent are lactose intolerant because the population has a long history of dependence on unfermented milk products.


Congenital lactase deficiency is inherited in an autosomal recessive pattern. This means both copies of the LCT gene in each cell have mutations. The MCM6 gene regulates the activity of LCT which gives instructions for making the lactase enzyme. Each of the parents carry a copy of the mutated gene but do not typically show signs or symptoms.

The MCM6 gene that is inherited by parents determines a person's ability to digest lactose in adulthood. Variations that promote lactase production are considered autosomal dominant. One copy of the altered element in each cell is sufficient. If a person does not inherit these variations from either parent they will have some degree of lactose intolerance.

What if I have lactose intolerance?

Remember that lactose is in all milk and milk products. Here are some things that may contain even the smallest amount of lactose:
  • bread and other baked goods
  • waffles, pancakes, biscuits, cookies, and the mixes to make them
  • processed breakfast foods (doughnuts, frozen waffles, toaster pastries, sweet rolls)
  • processed breakfast cereals
  • instant potatoes, soups, and breakfast drinks
  • potato chips, corn chips, and other processed snacks
  • processed meats (bacon, sausage, hot dogs, and lunch meats)
  • margarine
  • salad dressings
  • protein powders and bars
  • candies

Check the food label for ingredients. If it has these, it has lactose:

  • milk
  • lactose
  • whey
  • curds
  • milk by-products
  • dry milk solids
  • nonfat dry milk powder

Ensure you get enough vitamin D since milk product intake is limited.

There is no cure for lactose intolerance, but there are ways to live with it:

  • Eat or drink milk and milk products along with other foods
  • Spread milk or milk products throughout the day
  • Eat or drink milk and milk products that have reduced lactose
  • Eat or drink other foods instead of milk and milk products
  • Use lactase products

Others with Lactose Intolerance:


Sibley, Eric. "Lactose Intolerance." National Institute of Diabetes and Digestive and Kidney Diseases. N.p., n.d. Web. 20 Mar. 2016. <>.

"Diagnosis/Treatment/and Ethical Implications - Lactose Intolerance by Jess."Diagnosis/Treatment/and Ethical Implications - Lactose Intolerance by Jess. N.p., n.d. Web. 20 Mar. 2016.

"MCM6." Genetics Home Reference. N.p., n.d. Web. 20 Mar. 2016. <>.