Yogurt Improves Immune Status Among AN Patients During Refeeding

Adding yogurt to a refeeding program for patients with anorexia nervosa (AN) may have a positive effect upon their immune system, according to the results of a study by a team of nutritionists in Madrid, Spain (Eur J Nutr 2006;45:225).

Yogurt is fermented milk that contains live lactic acid bacteria, and has been reported to have a number of beneficial effects, such as balancing intestinal microflora, improving lactose tolerance, and shortening episodes of diarrhea. Even though few studies have been done among humans, animal studies have shown that lactic acid bacteria can improve immune status.

The authors, Esther Nova and colleagues at Hospital Infantil Universitario Niño Jesús, had previously reported immunocompromised status in patients with AN that shared characteristics with typical malnourished patients. In these studies, the authors reported that patients had leukopenia and impaired cell-mediated immunity, reflected by reduced delayed hypersensitivity tests, depleted T cell subcounts, and altered cytokine production.

In the recent prospective, randomized, controlled and parallel study, 16 patients with AN and 16 healthy controls consumed 375 gm/day (1 cup equals 227 gm) of natural yogurt containing the common bacteria Lactobacillus bulgaricus and Streptococcus thermophilus. The control groups of AN patients (14 patients) and healthy subjects (19) consumed 400 ml/day of semi-skimmed milk; the amount of milk was selected to approximately match the energy and nutrients supplied by the 375 gm of yogurt. Blood lymphocyte subsets were then assessed by flow cytometry and the in-vitro production of IL-2, IFN-y, IL-2, IL-6, and TNF.

Results

After 10 weeks, patients with AN who consumed yogurt had improved immune system status, particularly in the immunologic marker ratio CD4+/CD8+ and the production of IFN-y by lymphocytes. The CD4+/CD8+ ratio, an indicator of nutritional status, has been found to be decreased in malnourished children with kwashiorkor. This ratio was decreased significantly among the healthy controls and patients with AN who drank semi-skimmed milk. Leukocyte and lymphocyte counts were lower in the AN patients than in the healthy adolescents during the entire study.