What is Latose Intolerance – Cause, Signs and Symptoms, Treatment, Type of Diet

Lactose Intolerance

Introduction / Definition / What It means to be Lactose Intolerant

Lactose intolerance is an inability or insufficient ability to digest lactose, a natural sugar found in milk from animal sources. People who are lactose intolerant lack the enzyme lactase to help breakdown lactose; therefore, they develop gastrointestinal irritation such as stomach cramps, bloating, diarrhea and flatulence if they drink milk containing lactose (The National Institute of Diabetes and Digestive and Kidney Diseases, 2009). Dietary reconsideration is the most important part of the treatment and often the only one. Since dairy products provide many essential nutrients, especially calcium, vitamin D and protein for bone growth and muscle development respectively, alternative substitutes will include milk from plant sources such as soy and almond milk.


Lactose is a large sugar that is made of two simple forms of sugar named glucose and galactose. Normally, it gets absorbed into intestine and travel through bloodstream after getting broken down into these two forms of sugar. Lining the wall of the small intestine is the enzyme lactase that helps with the break down process, and in its complete absence or partial deficiency, the stomach can’t digest the lactose ( Roth, 2006).

Etiology / Causes

There are three main types of lactose intolerance:

  1. Developmental factor, also known as primary lactose intolerance, is most commonly caused by lactase deficiency. Human body naturally produces large amounts of lactase during infancy and early childhood as it gets fed with mother’s milk primarily. But as the baby’s breastfeeding schedule is reduced and more varied nutrient sources are introduced, the production of lactase decreases. This type of decrease in production usually begins after about age 2 and may not present with any symptoms until the adulthood age is reached, and therefore, sometimes it is also known as adult-hypolactasia. It is believed to be genetically programmed from the beginning, however, and the differences in prevalence of adult-hypolactasia among different ethnic groups are very noticeable.
  2. Secondary lactose intolerance though is more common during infancy, it can develop at any age because it is caused by illness in the intestinal walls of digestive system. Such gastrointestinal diseases include celiac disease, gastroenteritis and an inflammatory bowel syndrome of Crohn’s disease; they can involve injury or rupturing of the epithelium linings where lactase enzymes located. Sometimes antibiotics treatment regimen can trigger interferences with the production and activity of lactase.
  3. Congenital lactose intolerance is a rare form, in which babies are born with complete absence of lactase. It occurs due to mutation of gene responsible for lactase production and is inherited from parents. This gene is recessive in nature; therefore, both the parents must pass on this defective gene to the child to make baby lactose intolerance. Babies with this type of lactose intolerance are not able to tolerate even their own mother’s milk and exhibit symptoms shortly after birth (Stone, 2008 & Marks, n.d.).


Lactose intolerance is most likely to occur in adulthood and in certain ethnic groups.  According to a study published by the National Digestive Diseases Information Clearinghouse, “some 30 million to 50 million Americans are lactose intolerant, including up to 75 percent of African Americans and American Indians and 90 percent of Asian Americans.” The condition is least common among Americans of northern European descent (Lang, 2005).

Signs and Symptoms

Inside a lactose deficient person’s gastrointestinal system, lactose is left untouched until it reaches the large intestine (colon) where bacteria finally break them apart. This faulty metabolism leads to production of lactic acids and other chemicals which cause distress. The signs and symptoms of lactose intolerance usually begin 30 minutes to 2 hours after drinking or eating foods that contain lactose (MayoClinic Staff, 2010).  These symptoms include bloating, pain or cramps in the lower belly, rumbling stomach sounds, gas, loose stools, abdominal distention, and nausea. Feeling sick or presenting with these symptoms after consuming lactose containing milk for one time doesn’t make the person lactose intolerant; the symptoms have to repeat every time a product containing lactose is consumed.

Treatments / Medications / Alternative Diets or foods

Lactose intolerance has no cure; the treatment involves treating factors intensifying the symptoms and using alternative source of milk for dietary requirements. Many people take Lactaid capsules to help in digestion of milk sugars. Others take yogurt with active live culture of bacteria such as lacto acidophilus.  They are found to aid in “digestion of lactose because the lactic acid bacteria used to make yogurt deliver lactase to the small intestine, where it breaks down the lactose before it reaches the colon.” (Sanders, n.d.). Many people however avoid dairy milk and related products; they instead consume alternatives such as soy milk and take supplements to meet their daily intake requirements of nutrients – the ones that we usually meet just by drinking milk.

Dietary Requirements

Individuals vary in their degree of lactose intolerance. Therefore, taking milk with other foods or eating small amounts of lactose-containing products throughout the day might help if the symptoms aren’t severe. Lactose intolerance can lead to severe deficiency in calcium and vitamin D if alternative sources are not added to the diet to replace milk. Milk is a primary source of calcium, vitamin D and protein for many people. Human body contains more calcium than any other minerals. Calcium is an important component of bone and teeth, giving them strength and hardness. Calcium is also needed for nerves and muscle action, blood clotting, heart function and metabolism. The Adequate Intakes for calcium is about 1000mg daily for adults. (Roth,2006). Non-milk sources of calcium include rhubarb, sardines and salmon with bones, spinach, soy milk, orange, kale, almond, broccoli, pinto beans, tofu, and white tuna. Lactose-free dairy products such as ice cream and aged cheese are sometimes tolerated by people who are lactose intolerant (Rosdahl, 2008).

There are also many supplements available for both calcium and vitamin D; often they both are supplied within a same tablet. Deficiency of these two nutrients can cause osteoporosis.  Vitamin D helps in regulating absorption and excretion of calcium. Taking a lactase replacement such as Lactaid, Lactase and Surelac medications before eating dairy products helps reduce or eliminate the manifestations of lactose intolerance by predigesting the lactose (Black, 2006).

Protein is another essential nutrient whose primary source for many people, especially lacto-vegetarians, is the milk. The primary function of protein is to build and repair body tissues. The other functions include fluid and electrolyte balance to prevent edema, development of antibodies for healthy immune system, and being an important component of hormones and enzymes which regulate digestion and metabolism. The Dietary Reference Intakes protein is between 46 to 56g/day. Alternative milk sources such as soy and almond milk are not sufficient enough for protein requirements. This is because the proteins found in plant sources are incomplete. Some examples of non-milk sources of protein include meat, fish, eggs, grains, beans and nuts. (Roth, 2006).

There are some non-dairy foods that may contain lactose too. Often they are processed foods to which milk and milk products are added in varying amounts to prolong shelf lives. They include bread and other baked goods, processed breakfast cereals, instant potatoes, soups, and breakfast drinks, margarine, lunch meats, salad dressings, candies and other snacks, and mixes for pancakes, biscuits, and cookies (Marks, n.d.).

Nursing considerations

In conclusion, a client who is lactose intolerant will need to eliminate the offending dairy product or take an enzyme replacement. The client needs to be taught how to read food labels to recognize if lactose is part of an ingredient in the food. Symptoms can be managed through dietary changes. Nurse should provide calcium and vitamin D supplement to prevent deficiency and limit dairy milk consumption to one glass at a time and with other foods. Monitor the possible complications such as weight loss and malnutrition (Silvestri, 2005).


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