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What is Lactose intolerance? PDF Print E-mail

Dairy-free foods have been on the market in one form or another for many years. Recently the trend towards the development of dairy-free foods may have accelerated in unison with the rapid increase in the development of gluten-free foods. However what exactly does dairy free/milk-free/non-dairy/lactose free all mean? Part of the confusion stems from the fact that several different conditions can be involved in the adverse reactions to dairy products.

Lactose Intolerance
The most common affliction is lactose intolerance¹. Lactose intolerance stems from a comparative deficiency of the enzyme β-galactosidase otherwise known as lactase in the small intestine of affected individuals. β-galactosidase is needed to digest lactose, the disaccharide sugar found in milk, into glucose and galactose, which can then be absorbed into the small intestine and used for energy.
Without adequate activity levels of β-galactosidase, the lactose does not get digested or absorbed and thus finds its way into the large intestine (colon) where the intestinal flora are able to ferment this lactose. These bacteria ferment the lactose into carbon dioxide, hydrogen and water. The resultant symptoms are abdominal cramping, frothy diarrhoea and flatulence. The symptoms of lactose intolerance are not severe but are certainly annoying and uncomfortable. A very large number of consumers have some degree of lactose intolerance as it affects a high percentage of Asians, Africans and some ethnic Jewish populations. Although less frequently affected, 6 – 12% of Caucasians experience lactose intolerance.

Milk Allergy
True milk allergy is another condition that can lead to consumer demand for dairy-free products. Milk allergy involves a heightened response of the immune system to a particular food. The most well understood form of milk allergy is an immediate onset  food allergy (otherwise known as IgE-mediated milk allergy). This is where immunoglobulin E antibodies are formed that specifically reacts to one of the prominent milk proteins2. Casein and the primary whey proteins (β-lactoglobulin and α-lactalbumin) are the major milk allergens. Thus, in the case of true milk allergy, the culprit is milk protein and not milk sugar (lactose). Milk allergy is the most common amongst infants affecting about 2% of all infants under the age of three.

Most milk allergic individuals eventually develop tolerance to milk proteins and dairy products but milk allergy can persist for some into adulthood. As tolerance develops, the ability to tolerate baked milk products is often easier than tolerance to less processed forms of milk3. The symptoms of milk allergy can range from mild the like of skin rashes (hives) and eczema, to severe as with asthma, throat swelling, anaphylactic shock. While fatal reactions are rare, they can and do occur on occasion. This true milk allergy can be much more sever than lactose intolerance. The minimal provoking dose for milk in milk-allergic individuals is often very low. As little as 0.5ml of milk or 0.1mg of milk protein can provoke an allergic reaction in the most highly sensitive individuals4. Milk allergic consumers must completely avoid the ingestion of milk, dairy products and especially any milk-derived ingredient that contains detectable protein residues.

In addition to IgE-mediated milk allergy, other forms of milk hypersensitivity can exist, especially in early childhood. These conditions include eosinophilic oesophagitis (a swelling of the oesophagus), and food protein-induced enterocolitis (colic) where the role of milk is one of the possible triggers is well established. Possibly milk may be involved in other conditions including irritable bowel syndrome (IBS), Crohn’s Diseases, ulcerative colitis, and various other syndromes. Collectively these illnesses may be quite debilitating. As with immediate onset food allergies, the causative factors in these illnesses are milk proteins. While limited information is available on minimal provoking doses in such conditions, these individuals typically attempt to completely avoid all milk and dairy products.

Originally, dairy-free products were developed to appeal to individuals with lactose intolerance. Hypoallergenic infant formula has also been available for many years as an alternative to milk-based formula for infants with milk allergies.
Historically, “dairy-free” has meant lactose-free. The use of dairy free on a label did not always mean that the product was free of milk protein residues. Thus dairy free products might sometimes pose a hazard to milk-allergic individuals. At present no regulatory definition exists for the terms dairy-free or lactose-free. Since many lactose intolerant consumers can safely ingest some small amounts of lactose, such products probably could still contain small amounts of lactose, although no consensus exists on safe doses of lactose.
The term ‘non-dairy’ is another term that is used on occasion. It is used specifically on coffee creamers that do not contain real cream. The use of this term is actually mandated by government regulation. However, non-dairy creamers actually contain caseinates, a form of milk protein. Thus they are not suitable for milk-allergic consumers although they are typically lactose free. While the use of this term is required by regulation on selected products, its use is definitely confusing.

Kosher Labelling
Kosher pareve is yet another term that can signify the absence of milk. Kosher labelling adheres to Jewish food laws and the term ‘pareve’ does denote a product that contains no milk. Kosher labelling is not regulated by government but is instead regulated by various rabbinical groups.

Milk Derived Ingredients
Many food ingredients are derived from milk. Since consumers with lactose intolerance can safely ingest small amounts of lactose, only a few of these ingredients are clearly hazardous for such consumers. Non-fat dry milk powder, some whey-based ingredients and lactose are the key ingredients that must be avoided by those with lactose intolerance.
Among individuals with immediate and delayed onset milk allergies, the avoidance of milk-derived ingredients is more complicated. Basically, any milk-based ingredient with detectable milk protein residues has the potential to provoke adverse reactions. Some milk-derived ingredients have a very high content of milk protein including non-fat milk powder, casein and caseinates, whey, whey protein concentrates, and milk protein concentrates.
Milk protein hydrolysates can be derived from either the whey or casein fractions of milk. These hydrolysates have varying degrees of hydrolysis (percentage of amino acids that are broken). The safety of milk protein hyrolystaes for milk-allergic individuals is variable and dependent upon the degree of hydrolysis. Extensively hydrolysed milk proteins (>0.62 amino nitrogen to total nitrogen ratio) are likely safe. Extensively hydrolysed casein and whey are used as key components of hypoallergic milk formulas for milk-allergic infants.

Fermented Milk Products
Many dairy products are fermented including such popular products as cheese and yoghurt. The bacterial cultures used in dairy product fermentations are often able to degrade the lactose as a source of energy during the fermentation process. If the fermentation process proceeds for a sufficient amount of time, then the lactose level may decrease to the point that lactose-intolerant individuals can safely consume them. Individuals with lactose intolerance should seek out yoghurts that contain live cultures as they possess the β-galactosidase enzyme that will help with the digestion of any lactose. Since the fermentation period for yoghurts is relatively short, the lactose levels in yoghurt are not reduced to any extent.
Cheeses vary widely in lactose content, depending on the type of cheese. Much of the lactose from cheese is removed from the curds with the whey fraction. Cheddar cheese may contain only 10% of the lactose found in milk but this level may still be sufficient to provoke symptoms in some lactose-intolerant individuals.
As cheese ages, the lactose level continues to decline, so well-aged cheeses typically have the lowest lactose levels. However, great variability exists depending on the starter cultures and the cheese making procedures so general advice cannot be given about the safety of cheese for lactose-intolerant individuals.
With respect to immediate and delayed-onset food allergies, fermentation would lower the allergenic risk only if the fermenting bacteria were able to degrade the milk proteins present in the product. Most dairy-related fermentations are focused on lactose degradation and not upon proteolysis (protein degradation). Thus fermented products typically remain hazardous for individuals with milk allergies.

Food ingredients derived from milk:

  • Non-fat powdered milk Butter
  • Casein/caseinate Butter Acid
  • Whey and whey protein concentrates Butter Ester
  • Hydrolized Milk Protein Butter Oil
  • Casein Hydrolysate Starter Distillate
  • Lactose Tagatose
  • Lactoferrin Nisin
  • Bacterial Cultures (check substrate) Enzymes (check substrate)


If you have a lactose intolerance then you can find dairy products that specifically state “lactose free”. However, a milk allergy is a bit more complicated as ALL dairy products (and their by-products) need to be avoided. In instances such as this, milk may be replaced with oat milk, almond milk, soya milk, rice milk or quinoa milk. There are quite a few variants available in most good health shops and most supermarkets are now stocking soya and rice milk.
At present, only soya yoghurt is available to substitute for cow’s milk yoghurt and cheese remains a problem as there is no real substitute for an aged cheddar or a creamy brie! There are a few brands of vegan cheeses on the market, and it may be worth a try.

In conclusion:

Dairy can be avoided very successfully – it is a myth that one needs dairy products for ‘good strong bones and teeth’. There are many other food groups out there that contain way more calcium than milk could ever provide.
If we were to consume fresh, unpasteurised milk straight from the cow, there would be a lot less lactose intolerant people out there as raw milk actually contains the digestive enzyme ‘lactase’ which helps digest lactose – problem solved.
So if you are fortunate enough to source some fresh milk from a reliable producer, it may just be a solution. However, very few of us city-dwellers have that privilege, so it is still better to rather just avoid that nasty, processed, packaged abomination that we’ve been brainwashed  to believe is good for us.

Sources of Reference:

1. Miller et al., 2007
2. Jarvinen and Chatchatee., 2009
3. Nowak-Wegrzyn et al., 2008
4. Gendel et al., 2008