Lactose & Dairy


Nutrition Facts

What is lactose intolerance?

Symptoms of lactose intolerance?

Tips and Hints

Food Groups



Lactose is a type of sugar which is found in milk and milk products. It can also be found in a variety of other foods such as cheeses and yoghourts and ice creams and in medicines and pills. Lactose is too big a molecule to be absorbed by the intestine and so it is digested and split into two more simple sugars glucose and galactose which can then be absorbed by the body and used as nourishment. In order to do this the lining of the small intestine produces an enzyme lactase. When this is absent or in short supply, lactose digestion is impaired and symptoms can occur. The symptoms of lactose intolerance are therefore dose related and are not an actual allergy.

In infants, milk is the main part of the diet, whereas adults do not eat so much milk. This is particularly the case with animals who may also have lactose intolerance problems in adulthood - don't feed your adult dogs milk!). Hence it is natural and normal for lactase production to gradually decrease as the individual grows older and the diet becomes more varied. This tends to occur in childhood and adolescence in African Americans, Native American Indians, Mediterranean races, Arabs, Jews, and Asians. Northern European white races seem to keep lactase production the longest.

When lactase is absent, lactose passes through the intestine to the colon (large bowel), carrying extra fluid with it. Normally lactose would not reach the colon because it would be digested before it reached that level. In the colon, bacteria break down lactose into lactic acid and certain gases. Lactic acid is an irritant and laxative. It can cause symptoms such as bloating, diarrhoea, abdominal cramps, and gas or flatus.

Lactase activity is reduced in people with certain intestinal conditions such as Crohn's disease, ulcerative colitis, and celiac disease (gluten enteropathy). Patients taking certain drugs and alcoholic patients may also be lactose intolerant. Finally, patients with surgical removal of part of the stomach or a large portion of the small intestine may need to reduce lactose in the diet because there will be less active cells to produce the enzyme lactase - again a dosage effect.

It is important to remember that while lactose intolerance can cause quite uncomfortable symptoms, it does not cause damage to the intestine. The purpose of this diet is to eliminate lactose or reduce it to tolerable levels. One way of alleviating symptoms is to add a dose of lactase to the diet - a supplement of lactase is taken before a lactose meal.


Nutrition Facts
Dairy products are important sources of calcium, riboflavin, and vitamin D. Some lactose-intolerant people are able to tolerate certain dairy products in small amounts, and their diets may provide enough of these nutrients. Consult your doctor to check that you are keeping up a decent intake of calcium if you are on a dairy free diet. Make sure vitamin D (get enough sunlight) and phosphorous (fish is a good source) levels are also maintained to optimise utilisation of dietary calcium.


What is lactose intolerance?
Lactose intolerance is an inability to digest and absorb lactose (the sugar in milk) that results in gastrointestinal symptoms when milk or products containing milk are drunk or eaten.  Lactose is a large molecule which is a sugar that is made up of two smaller sugars, glucose and galactose. In order for lactose to be absorbed from the intestine and into the body, it must first be split into glucose and galactose. The glucose and galactose then are absorbed by the cells lining the small intestine. The enzyme that splits lactose into glucose and galactose is called lactase, and it is located on the surface of the cells that line the small intestine. Lactose intolerance is caused by reduced or absent activity of lactase that prevents the splitting of lactose (lactase deficiency). Lactase deficiency may occur for one of three reasons -

1. congenital which means it is present from birth, which is a rare form particularly since babies eat milk. This should not be confused with milk intolerance which can occur in infants and which is due to a reaction to cows milk proteins in babies fed on cows milk or given supplements.

2. secondary or developmental. This type of deficiency is caused by conditions which may have destroyed the intestinal lining and lactase - for example chronic severe diarrhoea from infections or coeliac disease.

3. Developmental - in most species of mammals the infant is capable of digesting milk and has adequate lactase for this task, whereas lactase is gradually lost with age as milk is no longer a part of the individuals diet.  This is the most common cause of lactase deficiency and is seen in many races to varying degrees. some eastern and Mediterranean populations may loose significant amounts of lactase relatively early on in life whereas white races from northern Europe keep lactase levels high until much later in life. (Prevalence of adult-type hypolactasia among different ethnic groups - Asian populations almost 100%, American Indians  80%, Negroid races 70%; Caucasians 20%. Age of onset Asian populations age 5, Blacks and Mexican-Americans age 10.)


Lactase deficiency does not equate exactly with lactose intolerance since milder deficiencies of lactase may cause no symptoms even persons with moderate deficiencies of lactase may not have symptoms. A diagnosis of lactase deficiency is made when the amount of lactase in the intestine is reduced, but a diagnosis of lactose intolerance is made only when the reduced amount of lactase causes symptoms.


What are the symptoms of lactose intolerance?

The common symptoms of lactose intolerance are gastrointestinal, primarily, abdominal pain, diarrhoea, flatulence (passing gas), and, less commonly, abdominal bloating, abdominal distension, and nausea. Unfortunately, these symptoms can be caused by other gastrointestinal conditions or diseases, so the presence of these symptoms are not very good at predicting whether a person has lactase deficiency or lactose intolerance.

Symptoms occur because the unabsorbed lactose passes through the small intestine and into the colon. In the colon, one type of normal bacterium contains lactase and is able to split the lactose and use the resulting glucose and galactose for its own purposes. Unfortunately, when they split the lactose into glucose and galactose, these bacteria also release hydrogen gas. Some of the gas is absorbed from the colon and into the body and is then excreted by the lungs in the breath. Most of the hydrogen, however, is used up in the colon by other types of bacteria. A small proportion of the hydrogen gas is expelled and is responsible for the increased flatus (passing gas). Some people have an additional type of bacterium in their colons that changes the hydrogen gas into methane gas, and these people will excrete only methane or both hydrogen and methane gas in their breath and flatus.

Not all of the lactose that reaches the colon is split and used by colonic bacteria. The unsplit lactose in the colon draws water into the colon (by osmosis). This leads to loose, diarrhoeal stools.

The severity of the symptoms of lactose intolerance vary greatly from person to person. One reason for this variability is that people have different amounts of lactose in their diet; the more lactose in the diet, the more likely and severe the symptoms. Another reason for the variability is that people have differing severities of lactase deficiency, that is, they may have mildly, moderately, or severely reduced amounts of lactase in their intestines. Thus, small amounts of lactose will cause major symptoms in severely lactase deficient people but only mild or no symptoms in mildly lactase deficient people. Finally, people may have different responses to the same amount of lactose reaching the colon. Whereas some may have mild or no symptoms, others may have moderate symptoms. The reason for this is not clear but may relate to differences in their intestinal bacteria.


Tips and Hints

Tolerance of lactose is variable. Some people can eat small amounts of lactose without having symptoms while others need to avoid it completely. This is a dosage effect.

Low-lactose diet: generally eliminates only milk and milk products. However, some can tolerate milk in small amounts (2 oz) throughout the day or as part of a meal. Some can tolerate small amounts of yogurt. These patients can experiment to find a level of lactose they can tolerate. Some people can build up their level of tolerance by gradually introducing the lactose-containing foods.

Lactose-free diet: all lactose products must be eliminated, including foods that are prepared with milk, both at home and in commercially packaged foods. These people may be able to use 100% lactose free milk or soy milk. Labels should always be read carefully.

Lactase Digestive Aids and Products: Many people can drink milk in which the lactase has been partially or completely broken down. Products are available as drops to add to the milk or as altered milk.  You may need to check local availability. (also see links)

Food Groups




Milk & milk products

100% lactose-free milk, soy milk

milk: whole, skim, 1%. 2%; buttermilk; sweet acidophilus milk; lactose-reduced milk; evaporated milk; acidophilus milk; sweetened condensed milk; instant hot chocolate and cocoa mixes; cheese


fresh, frozen, and canned vegetables without added milk or milk products; tomato paste and purée; tomato and spaghetti sauces without cheese

creamed or breaded vegetables, packaged dried potato mixes, tomato and spaghetti sauce with cheese


fresh, frozen, canned, and dried fruits


Breads & grains

water-based breads (Italian, French, Jewish rye), rice and popcorn cakes, graham crackers, rusks, Pareve-Jewish bakery products, cooked and dry cereals without added milk solids, pasta, rice, oats, barley, cornmeal, bulgar, and other plain grains

the following made with milk or milk products, breads, rolls, biscuits, muffins, pancakes, sweet rolls, waffles, crackers, instant and dry cereals with added milk products, some packaged grain mixes, packaged macaroni mixes

Meat and meat substitutes

plain beef; lamb; veal; pork; wild game; poultry; fish; shellfish; eggs; kosher prepared meat products; peanut butter; peas, beans, or lentils (dried, canned or frozen); all nuts and seeds; tofu

eggs, fish, meat, or poultry (breaded or creamed); luncheon meats; sausage; frankfurters; some brands of egg substitutes and powdered eggs

Fats & oils

bacon, butter, margarine without milk derivatives (whey), salad dressing without cheese or milk, vegetable oils, olives, most non-dairy creamers, mayonnaise, gravy made without milk or milk products

cream, half & half, sour cream, cream cheese, chip dips, some types of margarine, salad dressing with cheese or milk, whipped toppings

Sweets & desserts

angel food cake, gelatin, fruit ice, fruit popsicles, fruit roll ups, hard candy, gum drops, jelly beans, liquorice, fruit pie fillings

ice cream, ice milk, some brands of sherbet, soufflé, mousse, pudding, custard, packaged dessert mixes, milk chocolate, toffee, caramel, butterscotch


Postum, lactose-free nutritional supplements (Sustacal, Ensure, Nutren), vegetable juice, fruit juices and drinks, tea, carbonated beverages, beer, wine, distilled spirits (gin, rum, etc.), cocoa powder, most coffee

instant iced tea, instant coffee, Ovaltine, chocolate drink mixes, cordials, liqueurs, milk-based nutritional supplements (Carnation Instant Breakfast)


bouillon, broth, meat, or vegetable stock soups; bisques and chowders made with water, soy milk, or 100% lactose-free milk

cream soup, canned and dehydrated soup mixes containing milk products


popcorn, plain pretzels, plain potato and corn tortilla chips, salsa, mustard, ketchup, pickles, uncreamed horseradish, relish, sauces made without milk or milk products, sugar, honey, jams and jellies, maple and corn syrup, molasses, herbs, spices, salt, pepper

cream or cheese sauces, ranch-style or cheese-flavored snack pretzels or chips, cheese curls, sugar substitutes with lactose added, medications and vitamin/ mineral supplements with lactose added


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