Most of us view milk as a nutritious food with a host of health benefits. Therefore it may seem inconceivable that symptoms arise after consuming milk. However, milk can be a problem for some people where it may exacerbate skin, nasal or lung symptoms and even lead to digestive symptoms such as abdominal cramps and diarrhea.
What is milk diarrhea?
Milk diarrhea is increased frequency of bowel movement and usually watery stools after consuming milk and dairy products. This can be acute meaning that it arises suddenly and last for a short period of time, or it can be chronic where it is ongoing for months and even years. Most of the time milk diarrhea is due to condition known as lactose intolerance.
Sometimes this type of milk diarrhea arises with other conditions such as infectious gastroenteritis (example giardiasis), inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS). However, in these cases the food sensitivity is not restricted to just milk. Many other foods and beverages could also lead to diarrhea after it is consumed.
Causes of Milk Diarrhea
In some conditions milk can be an irritant to the digestive tract but this is not always unique to just milk and dairy in these cases. Lactose intolerance is one condition where milk and dairy triggers digestive symptoms like cramping, flatulence and diarrhea. The problem lies with the body’s inability to digest the milk sugar known as lactose, which then causes a host of disturbances within the gut.
Normally the enzyme lactase breaks down the milk sugar lactose in the small intestine. Lactose that is present in milk is a disaccharide. It has to be hydrolyzed into a monosaccharide in order for it to be absorbed in the gut. The deficiency of the enzyme lactase means that the lactose will remain in the gut. It passes through the small intestine and eventually into the large intestine.
Primary and Secondary Lactose Intolerance
Primary lactose intolerance is where there is a deficiency of the enzyme lactase. It arises in late childhood although a rare form may be present from birth. Secondary lactose intolerance usually occurs in the backdrop of other diseases. Most of the time it presents with diarrheal illnesses where the intestinal lining is damaged. It may also arise with the use of medication and consumption of various substances that affect the intestinal lining.
Signs and Symptoms
The unabsorbed lactose draws out water from the body into the gut. It causes the gut to distend and increases bowel transmit time. The bacteria in the colon then consumes the undigested lactose. Collectively these disturbances leads to the gastrointestinal symptoms that are characteristic of lactose intolerance. This includes:
- Excessive flatulence
- Abdominal cramps
- Vomiting (sometimes)
The symptoms of lactose intolerance appear between 30 minutes and 2 hours after consuming milk or other dairy products. The effect is short-lived as lactose is passed out of the gut or digested by the colonic bacteria. Eventually the symptoms resolve and only return if milk and dairy is consumed again.
Other gastrointestinal conditions are sometimes mistaken for lactose intolerance. Therefore the presence of the symptoms alone is not always a reliable indicator. Laboratory investigations should be conducted to confirm a diagnosis of lactose intolerance.
Prevention of Milk Diarrhea
Contrary to popular belief, milk and dairy products does not have to avoided altogether for most people with lactose intolerance. Studies have shown that in most instances a person with primary lactose intolerance can consume around 200mL (7oz) of milk without experiencing any significant symptoms. Overall the key is moderation.
- Consume small portions of milk and dairy. Avoid only in severe cases where even small portions of dairy triggers symptoms.
- Choose dairy that is lactose-reduced. Lactose-free varieties of some foods may also be available and should be used if well tolerated.
- Processed foods should be selected with caution as there may be hidden lactose in many foods. It may not be a problem in small quantities but large quantities can trigger acute episodes.
- Opt for calcium-rich non-dairy foods like vegetables and along with a balanced diet, the reduced or absent dairy intake may not lead to any severe problems.
Patients with secondary lactose intolerance should avoid dairy altogether. This type of lactose intolerance is usually acute and dairy can be consumed again once the underlying condition resolves. Since it persists only for a few days o weeks, there is no significant risk of calcium deficiency.
It is important to note that some people may find that whole milk is better tolerated than skim milk. Lactose intolerance is not related to processed or preserved milk only. Therefore unpasteurized milk may not be beneficial and can be dangerous due to bacteria within the milk.
Read more on foods for lactose intolerance.
Treatment of Milk Diarrhea
There is no specific drug for lactose intolerance. Prevention is usually the main focus for managing primary lactose intolerance. With secondary lactose intolerance, the need to avoid milk and dairy is short term. Eventually the condition will resolve and milk can be consumed again.
There are commercial preparations of the enzyme lactase but it is not a cure. These preparations may help reduce symptoms in some people but others may not always find it as effective. Supplementation with calcium may be advised due to reduced milk intake, however, this is not always necessary when there is proper balanced nutrition.
Prognosis and Complications
Lactose intolerance is not as uncommon as is often thought. Estimates suggest that it may affect as much as 75% of the global population. Since the symptoms may be absent unless large quantities of dairy is consumed, many people may not be aware that they have lactose intolerance. The prognosis is excellent and there is complete recovery within a short period of time, especially if dairy is not consumed again or in large quantities.
Although lactose intolerance is not life-threatening and the impact of it on regular life is minimal, complications can arise. The main complication is osteopenia where there is reduced bone mass density known as osteopenia. It is not as severe as osteoporosis. However, it can be avoided with moderate dairy consumption and a balanced eating plan containing calcium-rich foods.