Pediatric diarrhea and lactose products

Clinical question

Are lactose-containing formulas and diets associated with worsened acute pediatric diarrhea?

Bottom line

Breastfed children should continue breastfeeding. In formula-fed children younger than 2 years, temporarily switching to lactose-free infant formula shortens diarrhea duration by about 18 hours and reduces treatment failure (9% vs 17% control) at 24 to 72 hours. The effects of cow’s milk have been investigated in only 3 small, older RCTs and their results are likely unreliable.

Evidence

Differences were statistically significant unless stated.

• In 4 systematic reviews (22 to 33 RCTs) with 2215 to 2973 mostly hospitalized (clinically stable) formula-fed children with acute diarrhea receiving oral rehydration^1-4:

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    In comparisons of lactose-free versus lactose-containing diets, the focus was on the largest systematic review (children aged 1 to 28 months).¹ Duration of diarrhea was 18 hours shorter among those with lactose-free diets, with median diarrhea duration (calculated by authors) 2.8 versus 3.5 days.¹ Treatment failure (continued or worsening diarrhea or vomiting, need for rehydration, weight loss) occurred in 9% versus 17%, respectively, over 24 to 72 hours (number needed to treat [NNT]=14).¹ Duration of hospitalization¹ and changes in weight^1,2,4 did not differ. Results of other systematic reviews were similar.^2-4
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    A systematic review (9 RCTs, 687 children)¹ found diluting lactose-containing formula (by 25% to 50%) reduced treatment failure compared with full-strength formula: 11% versus 17% over 24 to 72 hours (NNT=17). Duration of diarrhea^1,3,4 and changes in weight^1,2 did not differ.

• Two RCTs (about 70 children each, mean ages 7 to 15 months)^5,6 compared diets with and without cow’s milk: no difference in diarrhea duration. An RCT comparing full-strength and diluted cow’s milk (62 children, mean age 22 months)⁷ found no difference in treatment failure.

• Limitations: Many RCTs were not blinded,^1,5-7 baseline illness duration was not reported,^1-4 and statistics are difficult to interpret clinically.^2,4 The RCTs on cow’s milk are old^5-7 (>30 years) and not generalizable (cow’s milk was given to infants at 3 to 6 months).⁵ No RCTs have involved older children.

Context

• Infectious gastroenteritis (particularly rotavirus) is associated with transient lactase deficiency⁸; rotavirus was the most common etiology in trials.¹

• Guideline suggestions to change or dilute formula predated current systematic reviews.^9,10

Implementation

During acute episodes of diarrhea, children should be monitored for signs of dehydration (eg, decreased urine output, lethargy)⁹; if present, rehydration should be prioritized to replace losses and achieve adequate fluid and electrolyte balance.¹¹ Intravenous hydration should be provided if the oral route is inadequate. Breastfeeding should continue (or increase) during initial rehydration.¹¹ Temporarily switching formula-fed infants to lactose-free formula can reduce diarrhea duration.¹ Once dehydration is corrected, the child’s usual diet should be resumed as tolerated.^9,10 It may be reasonable to limit cow’s milk in favour of lactose-free fluids, but there is little evidence for this or the avoidance of other lactose-containing foods.

Tools for Practice articles in CFP are adapted from peer-reviewed articles at http://www.toolsforpractice.ca and summarize practice-changing medical evidence for primary care. Coordinated by Dr G. Michael Allan and Dr Adrienne J. Lindblad, articles are developed by the Patients, Experience, Evidence, Research (PEER) team and supported by the College of Family Physicians of Canada and its Alberta, Ontario, and Saskatchewan Chapters. Feedback is welcome at toolsforpractice@cfpc.ca.