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The skinny on lactose intolerance

Glass of Milk

 (iStock)

Dairy can be a surprisingly heated topic in certain circles.  One line of reasoning argues that because humans are the only mammals that continue to consume dairy after infancy, and because there is a high prevalence of lactose intolerance in some cultures, eliminating from our diet would be best.  

Allergy vs. intolerance
There is a distinct difference between a food allergy and a food intolerance.  A food allergy provokes an immune response to a particular substance.  With milk, people are allergic to the protein –usually  casein.  In rare cases, some people are allergic to bovine proteins, which are found in milk and in beef.  For some, it may trigger a life-threatening anaphylactic reaction.  

An intolerance or malabsorption implies difficulty with absorption of nutrients.  Lactose intolerance means difficulty absorbing nutrients from milk (lact) and sugar (ose).  When we digest lactose, it is broken down in the small intestine by the enzyme lactase into glucose and galactose.   The galactose is modified to become a glucose molecule for utilization in the body by the liver.

Nature vs. nurture
Lactose intolerance has several causes.   In rare cases, it is caused by a rare-autosomal recessive trait, in which the body cannot create the enzyme lactose at all.  Primary lactase deficiency tends to occur in adults, in which they lack the lactose persistence gene.  Just as it sounds, the body loses its ability to produce the enzyme lactase over time.

However, as humans “domesticated” dairy animals and continued to consume dairy products, the gene for lactose persistence has prevailed for survival.  In many cultures, dairy products from various mammals, such as cows, sheep and goats, can feed more individuals than the meat of the animal alone.   

Prevalence
In 2010, the National Institutes of Health (NIH) published a consensus statement about lactose intolerance and health.  They concluded that “lactose intolerance is a real and important syndrome, but its true prevalence is not known.”  It further suggests that many people have lactose malabsorption compared to a clinical intolerance.   

This may be among the most widely self-diagnosed health ailments.  The moment people feel gas after eating, they assume they have an allergy or intolerance to a food.  The act of digestion, does indeed produce gas as a bi-product, the problem is when it is excessive and may be accompanied by cramping and diarrhea.  It is important that it be diagnosed by a physician.

What you may be missing
The NIH Consensus statement alludes that “individuals with real or perceived lactose intolerance avoid dairy and ingest inadequate amounts of calcium and vitamin D, which may predispose them to decreased bone accrual….”  The correlation between dairy consumption and bone health has been well-established, whereas we continue to see growing research about vitamin D and its impact on health and disease.

Can you still have dairy products?
The simple answer is yes.  There are many brands of lactose-free dairy products and lactose digestive aids.  Many people who are lactose intolerant (or malabsorptive) can eat yogurt and have no gastrointestinal issues because of the active live cultures, like lactobacillus bulgaricus.   Hard cheeses like parmesan, Swiss, cheddar and colby have smaller amounts of milk sugar and great quantities of milk solids which make them well-tolerated.  In many instances, having a small glass of milk at the end of a meal can be handled without discomfort.

So there is no need to give up dairy if you are lactose intolerant.  Certainly in these challenging economic times, it is a great way to get a nutrient-rich food, which can be low in cost.   Low-fat and fat-free dairy are great sources of protein, without all the saturated fat.  Dairy has been part of the Mediterranean diet and certainly has its presence in the USDA’s My Plate recommendations.