What’s the difference between lactose intolerance and CMA?

Are you confused about the difference between lactose intolerance and cow’s milk allergy? Do you have a child or teen with suspected lactose intolerance or cow’s milk allergy? Perhaps it runs in your family? Many people, and some professionals, don’t understand the difference between these two common conditions. This is especially important for children, as restricting whole food groups like dairy can impact important nutrients like calcium, needed alongside Vitamin D for bone growth. This blog highlights the main differences between these two cow’s milk difficulties.

So, what is Lactose Intolerance?

Lactose Intolerance is a digestive problem, arising when the digestive enzyme lactase, is insufficient or absent. The role of lactase is to break down, or digest, lactose found in mammalian milks, such as breastmilk, cows, sheep or goat milk, soft cheeses and yoghurt. Lactose intolerance does not harm the small intestine, but can result from injury or infection to the delicate tissues of the small intestine. I discuss different types of lactose intolerance below.

What about Cow’s Milk Allergy?

Cow’s Milk Allergy affects some infants in their first year and is an immune, (rather than a digestive) problem. An immune reaction to milk proteins in the diet eg. from cow’s milk, infant formula and foods containing milk plus yoghurt, cheese, butter and cream. Some infants may be sensitive to the cow’s milk proteins which transfer to mum’s breast milk after eating dairy foods. For other infants, starting solid foods containing fresh dairy is the triggering event. A spectrum condition, with a wide range of presentations, symptoms of Cow’s Milk Allergy range from mild and short-lived to severe and persisting. An allergy focused history, milk exclusion and diagnostic challenge are needed to develop a clear plan for dietary treatment. Features of cow’s milk allergy for you to consider include:

• The history of exposure to milk proteins; timing and severity of reactions;
• Ongoing symptoms; infants age at onset; infants feeding journey

Symptoms of Lactose Intolerance

In the presence of large amounts of undigested lactose in large intestine two things happen:

1. Water and salts are drawn into the large bowel (by osmosis) from the surrounding tissues causing urgency and explosive, loose stools
2. Large amounts of undigested lactose undergo bacterial fermentation by the gut microbiota producing gases and acids, responsible for bloating, discomfort and wind

Types of lactose intolerance

• Primary - World-wide, primary lactose intolerance is the most common form. Its results in the gradual loss of lactase production, also called lactose non-persistence and related to aging and the person’s genetic, evolutionary diet
• Secondary - Usually a temporary condition, as a result of small intestine damage from surgery or illness. Common causes are viral or bacterial infection eg. rotavirus; allergic inflammation, coeliac disease and chemotherapy
• Developmental - In extremely premature infants before 30 weeks, lactase activity is absent in the infant’s small intestine. Activity typically begins to increase during the third trimester of pregnancy from around 30-32 weeks
• Congenital - Also called alactasia, an inherited condition where there is an absolute absence of the enzyme lactase. Infants and children need a lactose free formula or milk and develop diarrhoea and failure to thrive on breast milk

Factors influencing lactose intolerance

• Increasing Age - Lactase enzyme production is high in infancy and decreases progressively with age, with reduced milk drinking, alongside a general slowing of tissue repair and renewal. As the primary natural source of nutrition in breast milk, lactase activity is high in infancy, and typically drops around age 3-5 years. Young children who continue to drink milk maintain good lactase production throughout childhood
• Breast-Feeding - Lactose, the sugar in all mammalian milk, including human milk, acts as a food source for the infant and stimulates the production of beneficial bifidobacteria in the infant’s gut microbiota. Some strains eg. animalis lactis producing lactase. Gut microbes also break down, or digest, lactose by bacterial fermentation
• Evolutionary Diet - Around 70% of the world’s population did not evolve drinking milk after early childhood, and as a result have low or no lactase enzyme activity beyond this age. Populations originating from India, Asian, Pacific, Africa and South American including mixed races with a mixed gene pool

Role of the Gut Microbiota

Digestion by bacterial fermentation of lactose occurs in the large intestine by specific strains of bifidobacteria, and part of the gut microbiota. This microbe species contributes to the normal, everyday digestion of lactose, which has not been digested by enzyme activity in the small bowel. Small, regular amounts of lactose provide food for these friendly bifidobacteria, and contribute to maintaining this species, which in turn keep other harmful bacteria limited. Lactobacillus, another keystone gut microbe species, and found in fermented dairy foods, can help people with symptoms of lactose intolerance. We know from experience and research that fermented dairy foods, such as yoghurt and kefir have long been associated with alleviating diarrhoea, good tolerance to lactose, as well as digestive wellness. This research article goes into more detail, for those science-minded folks! https://pubmed.ncbi.nlm.nih.gov/29425071/

Does my child have Lactose Intolerance or Cow’s Milk Allergy?

I hope this blog has been helpful and provided some context for lactose intolerance. Here are some top tips to help you get more clarity:

• Consider the full range of symptoms – what seems more likely?
• Consider other factors eg. ethnicity and evolutionary diet
• What kind of lactose intolerance might you suspect?
• Has there been recent infection or tummy upset, has there been a change in the usual diet?
• Hard cheeses are well-tolerated in lactose intolerance, fresh cow’s milk is high in lactose and will not be tolerated
• Neither cheese nor fresh cow’s milk would be tolerated with cow’s milk allergy
• Lactose free milks and cheeses made from cow’s milk contain cow’s milk protein, making them unsuitable for those with cow’s milk allergy
• Vegan cheeses, whilst lactose and cow’s milk protein free have poor nutritional value and contain no or very little protein. Often these products are poorly fortified with calcium or other vitamins naturally present dairy foods including Vitamin A, Vitamins B2, B3, B5, B12 and Calcium and phosphorus.