Goodness of Milk & Lactose Intolerance

This article discusses the benefits of milk as well as its challenges such as lactose intolerance.

There is nothing like our mother’s milk to sustain us for the first year of life and beyond. Rich in vitamins, proteins, fats, carbohydrates, and other essential nutrients, milk is the perfect food to nurture and sustain healthy human growth. Once weaned from mother’s milk, humans have another excellent source of many of these nutrients readily available in cow’s milk and most Canadian children make this transition after infancy.

Along with its key dietary components, cow’s milk is also a natural source of many other vital nutrients and commercially sold milk comes fortified with vitamin D. Milk is 90% water, so it’s an effective thirst quencher. It is also the most abundant and easily accessed source of calcium in the North American diet, with one cup supplying about 300 mgs of calcium. Many people consume milk all though their lives with no difficulties but others suffer reactions to milk, the most common of which is lactose intolerance.

Milk, forsythia flowers, and a few tropical shrubs are the only natural sources of lactose.

Lactose Intolerance vs. Protein Allergy

Lactose is the sweet carbohydrate component of milk that consists of two bonded simple sugars. The body cannot digest this type of bonded sugar, a disaccharide, and needs an enzyme called lactase (a protein) to break down the structure into glucose and galactose, its constituent monosaccharides.

When your lactose intake exceeds the lactase production capacity of your small intestine, lactose will pass undigested to the large intestine where it creates symptoms of gas, abdominal distension, pain, diarrhea, and even vomiting, which typically occur about thirty minutes to two hours after eating lactose-containing foods.

Lactose intolerance can sometimes be confused with milk allergy, an immune reaction to one or more of the many proteins in milk. Allergic reactions include similar symptoms to lactose intolerance, in addition to skin rashes, gastroesophageal reflux disease, upper respiratory tract problems, and anaphylactic shock. An allergy to cow’s milk is rare, occurring in only 2-3% of infants, and less frequently in adults. A high percentage of those allergic to cow’s milk are also allergic to other animals’ milk (e.g. goat’s milk) and soy beverages. They also tend to have a family history of allergies.1

Symptoms localized to the gastrointestinal tract are more indicative of lactose intolerance than true allergy, and lactose intolerance is more likely to develop over time.

Types of Impaired Lactose Digestion

Primary lactase deficiency results from a decrease in lactase production that begins in early childhood during the transition from mother’s milk to fuller diet.2 This reduction in lactase will induce varying levels of the symptoms associated with lactose intolerance. Primary lactase intolerance is the most common variation, affecting nearly 70% of adults worldwide in varying degrees.3

Secondary lactase deficiency results from a primary disease, (e.g. celiac disease, Crohn’s disease, and gastroenteritis) a long course of antibiotics, radiation or chemotherapy, or severe malnutrition. However, this condition typically clears up with improved health and nutrition, and is usually temporary in nature.4

Congenital lactase deficiency is a rare and irreversible genetic disorder where an infant is born without the ability to produce lactase.5

Lactose Intolerance Diagnosis

You might think you have lactose intolerance if you don’t feel well shortly after having a glass of milk or a cup of yogurt. However, this reaction on its own is not an indicator that you are intolerant to milk products. Symptoms related to lactose intolerance occur soon after ingestion, so you could try an easy ‘test’ by avoiding dairy for a few days or a week to see if digestive symptoms resolve. Then, while gradually re-introducing milk products into your diet, make a note of any symptom return, so you can take this record to your physician for discussion. Your physician might ask you to have one or more of three common tests to confirm how your body is handling lactose. These tests are the hydrogen breath test, a lactose tolerance test, or a stool acidity test. It is important to consult a medical professional regarding a lactose intolerance diagnosis since symptoms of this disorder could be similar to those of other conditions.

Options for the Lactose Intolerant

While the amount of lactase produced in the small intestine tends to decrease after infancy, continuing to ingest milk and milk products seems to promote ongoing lactase production. The degree of lactose intolerance can vary widely, and there are many options for each individual situation. Most people can gradually challenge their systems to increase lactase production. A progressive increase in milk intake and the consumption of small amounts of milk more frequently will help stimulate lactase production. Drinking milk in conjunction with other foods will help slow digestion, reducing your chance of experiencing an unpleasant reaction.6

Many lactose intolerant individuals can enjoy some types of dairy products due to either reduced lactose or helpful bacteria (probiotics) found in these products. Hard aged cheese, such as cheddar and Swiss, and soft ripened cheeses have lower concentrations of lactose, making them more easily digestible, even for those with lower lactase production. The bacteria used in the production of yogurt, curd, and kefir produce a lactase-like enzyme, thereby aiding in the digestion of these foods. Reading product labels is important, as many cheeses and yogurts often include additional milk solids containing lactose.7

Commercial Products Help

Commercial products are available, either in the form of Lactaid® dietary supplement, containing just the enzyme lactase, or Lactaid® milk products wherein the lactose has already been broken down. One noticeable difference in pre-treated products is their distinctly sweeter taste, which results when the lactase reduces sugars to their simplest forms. Digesta® is a dietary supplement formulation containing lactase and other enzymes specifically designed to enhance the digestion of dietary carbohydrates, fats, and proteins.8 It is important to take either dietary supplement with the first bite of lactose-containing foods for greatest efficacy.


If you’re hoping to avoid lactose altogether, there are many ‘alternative’ commercially available plant-based milks, cheeses, and yogurts. See our page on Milk Alternatives for a list of these.

Those intolerant to any dairy should be wary of processed foods, since lactose is often used for texture, flavour, and adhesive qualities in sausages, sliced breads, breakfast cereals, dried fruits, potato chips, protein supplements, and prepared meals – to name a few. As mentioned above, read labels carefully to identify which products contain variations on lactose such as milk solids, milk ingredients, milk by-products, and whey.9


Don’t discount the goodness of milk, nor remove it from your diet without proof that milk is causing your symptoms. Make sure to see your physician for appropriate diagnosis, and seek the advice of a registered dietitian for guidance on how to gradually build your body’s tolerance to milk and other dairy products. A dietitian can offer advice on more easily digested milk products and work with you to ensure you do not miss any of the important nutrients found in this remarkable natural food.

More Information about Milk

Eating Well With Canada’s Food Guide Daily Recommendations for Milk & Alternatives

Age (Years)
2-8 9-13 14-18 19-50 51+
Servings 2 3-4 3-4 2 3


One Serving for Milk & Alternatives Equals

Milk or Powdered Milk
Canned Milk (Evaporated)
Fortified Soy Beverage
Yogurt/Kefir Cheese
250mL/1 cup 125mL/½ cup 250ml/1 cup 175g/¾ cup 50g/1½ ounces


Nutrients in Milk

Milk products are one of the most under-consumed of the four food groups in Canada’s Food Guide. By not getting enough, you could be missing out on the valuable health benefits milk products offer.

CALCIUM Necessary for strong healthy bones and teeth. Contributes to heart beat, muscle contraction, proper nerve function, and normal blood clotting.
VITAMIN D Maximizes calcium and phosphorus absorption upon which strong bones and healthy teeth depend.
Note: At present, vitamin D is added to milk only, although certain brands of yogurt are now made from fortified milk and thereby provide vitamin D.
VITAMIN A Promotes healthy skin, eyes and night vision. Essential for healthy bones and teeth.
PROTEIN Contribute to the building and repairing of body tissues, including bones. Help build antibodies that fight infections.
POTASSIUM Essential for maintaining your body’s vital fluid balance. Important for the proper functioning of nerves and muscles.
RIBOFLAVIN Promotes healthy skin, eyes and nerves. Helps convert food into energy.
NIACIN Essential for growth and development, and for a healthy nervous system and digestive tract.
VITAMIN B12 Contributes to the health of red blood cells and to the maintenance of a healthy nervous system and digestive tract.
PHOSPHORUS Helps build strong healthy bones and teeth, and contributes to the overall proper functioning of your body.
THIAMIN Turns carbohydrates into energy. Maintains a healthy appetite and helps normal growth.
VITAMIN B6 Helps protein build body tissue. Contributes to the production of red blood cells and antibodies to fight infections.
PANTOTHENIC ACID Helps turn carbohydrates and fat into energy your body can use.
FOLIC ACID Participates in the formation of red blood cells and of genetic material for cells.
MAGNESIUM Contributes to the health of bones and teeth; helps convert food into energy, and builds body tissue.
ZINC Converts food into energy. Plays an important role in tissue repair and growth.
SELENIUM Acts like an antioxidant, thereby contributing to the protection of the cells. Contributes to the proper functioning of the immune system and is essential to the metabolism of thyroid gland.


First published in the Inside Tract® newsletter issue 166 – March/April 2008
2. Bhatnagar S, et al. Lactose Intolerance. British Medical Journal. 2007; 334: 1331-1332.
3. American Dietetic Association. Lactose Intolerance: The Food Sensitivity Series. Chicago: American Dietetics Association; 1985.
4. Mayo Foundation for Medical Education and Research. Lactose Intolerance:
5. Dahlqvist A. Lactose Digestion and Lactase Deficiency. In: Delmont J ed. Milk Intolerances and rejection. Basel, New York: Karger;1983.
6. Dahlqvist 2.
7. Mayo Foundation for Medical Education and Research 7.
9. American Dietetic Association 4.
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