Does Dairy Cause Constipation?

Does Milk Cause Constipation?

No one likes feeling “blocked up.” Constipation is medically defined as having less than three bowel movements per week. If you have less than one bowel movement per week then you are considered to have severe constipation. Symptoms include bloating, gas, or pain passing a bowel movement. Diet can serve as a way to alleviate constipation; however milk has been considered to be a cause of constipation since the 1950’s (Crowley & Colleagues, 2013). A sensitivity to cow’s milk protein (CMP) has been proposed as a possible cause for chronic functional constipation (CFC).

What does the literature say?

Much of the research looking at the association between cow’s milk and constipation dealt with young children as CFC is a common phenomenon in them. In 2008 Crowley and colleagues conducted a review assessing the evidence for a causal relationship between CMP intake and CFC in children. They found a small body of evidence suggesting, not concluding, that consumption of cow’s milk protein is associated with CFC. They stated that randomized trials were needed to provide higher level evidence (Crowley & Colleagues, 2008).

The same researchers conducted a cross-over study in 52 children (ages 1-12), diagnosed with CFC. For the first two weeks, the children either received 400 ml of cow’s milk or soy milk, followed by a washout phase of two weeks (during which they drank neither cow’s milk nor soy milk). During the last two weeks of the trial following the washout phase, the children drank the alternate beverage (so if they started the trial drinking cow’s milk, they would then alternate to soy milk). This trial showed that removal of cow’s milk significantly increased the number of bowel movements and improved constipation, suggesting that cow’s milk protein played a role in CFC for these children (Crowley & Colleagues, 2013).

In the second trial, the researchers did the same cross-over study with washout, but compared cow’s milk beta casein A1 and cow’s milk beta casein A2. Casein is one of the major proteins in cow’s milk and different breeds of cows produce either A1 or A2. Seventy one percent and 57% of those on A2 and A1 milk, respectively, experienced resolution of their constipation. There was not a statistically significant difference between the percentages and the researchers could not precisely identify why there were improvements in constipation. They speculated that the resolution in CFC may have been due to the washout phase, where 81% of constipation was resolved. The researchers concluded that there is an association between CFC and cow’s milk consumption, but probably not one between the different types of casein (Crowley & Colleagues, 2013).

Similarly, in a 2010 cross-over study published in the Journal of Pediatric Gastroenterology and Nutrition, Irastorza and colleagues concluded that there was a clear association between cow’s milk consumption and constipation in more than one-third of the 69 children diagnosed with chronic constipation in their study (Irastorza & Colleagues, 2010).

Based on these findings, there appears to be a link between cow’s milk consumption and constipation. However, these studies looked at children rather than adults and therefore may not be applicable to the general population. A possible reason as to why cow’s milk could cause constipation is that when it is pasteurized, some of the enzymes that would otherwise help digest the milk are lost. Additionally, new intensive farming techniques have led to cows being fed grains rather than grass, and this may induce constipation in those especially sensitive to grains (“Can Milk Cause Constipation?”). If you are experiencing any form of constipation, eating adequate amounts of fiber (25-30 grams a day), and water can help alleviate your symptoms. You can find fiber in whole grains, fruits, vegetables, and legumes. Staying active every day will also help stimulate your bowels. Probiotics, such as those found in yogurt and fermented foods can also be very helpful in keeping you regular. Speak with your doctor if your constipation does not seem to resolve.

References

• “Can Milk Cause Constipation?” Constipation Experts, 2015, http://www.constipationexperts.co.uk/blog/2014/06/can-milk-cause-constipation.html

• Crowley, E.; Williams, L.; Roberts, T.; Jones, P.; Dunstan, R. Evidence for a role of cow’s milk consumption in chronic functional constipation in children: Systematic review of the literature from 1980 to 2006. Nutrition and Dietetics. 2008, 65, 29–35.

• Crowley, E., Williams, L., Roberts, T., Dunstan, R., & Jones, P. (2013). Does Milk Cause Constipation? A Crossover Dietary Trial. Nutrients, 5(1), 253-266. doi:10.3390/nu5010253

• Irastorza, I., Ibañez, B., Delgado-Sanzonetti, L., Maruri, N., Vitoria, J. C. (2010). Cow's-Milk–free Diet as a Therapeutic Option in Childhood Chronic Constipation. Journal of Pediatric Gastroenterology and Nutrition, 51(2) 171–176.