Lactose intolerance and self-reported milk intolerance: relationship with lactose maldigestion and nutrient intake. Lactase Deficiency Study Group.
BACKGROUND
The relationship between lactose-maldigestion, self-reported milk intolerance and gastrointestinal symptoms has not been clearly defined.


OBJECTIVE
To evaluate: a) the prevalence of lactose maldigestion and lactose intolerance in a sample of the general population taken from a rural center; b) the frequency of self-reported milk-intolerance and its correlation with lactose-maldigestion; c) the influence of lactose maldigestion, lactose intolerance and self-reported milk intolerance on dietary habits and consumption of total calories, protein, and calcium.


METHODS
We studied a randomized sample of the general population in a small center in Sicily. 323 subjects (150 males, 173 females), age range 5 to 85 years (median 44) were included and underwent H2-breath test after 25 g lactose load. The preliminary dietary investigation spanned 7 consecutive days using a printed dietary form and was under the daily control of a team of dietitians.


METHODS
The dietary investigation was completed in the first part of the study and the results were analyzed for nutrient composition by a computerized database. The subjects were then divided into self-reported milk-intolerants and self-reported milk-tolerants and they underwent H2 breath testing; subjects with H2 concentration >20 ppm over the baseline concentration were considered maldigesters and those with one or more symptoms were classified as intolerants.


RESULTS
104/323 subjects (32.2%) were lactose maldigesters but tolerants, while 13/323 (4%) were lactose maldigesters and intolerants. In each age-class group (pediatric, adult, and elderly subjects) only the lactose maldigester and intolerant subjects showed differences in nutrient intake with a significantly lower daily consumption of milk and a lower calcium intake. 49/323 subjects were self-reported milk-intolerants; of these, 26 (53%) were lactose maldigesters but tolerants, 18 (37%) were lactose digesters and tolerants and only 5 (10%) were lactose maldigesters and intolerants. In the whole group of self-reported milk-intolerants, dietary milk consumption was significantly reduced and calcium intake was lower than in all the other subjects studied (320 mg/day vs. 585 mg/day, p<0.05).


CONCLUSIONS
In studies of the general population, the frequency of lactose intolerance is much lower than that of lactose maldigestion. Gastrointestinal symptoms after lactose load in self-reported milk-intolerants are found in only a very low number of these subjects. Furthermore, in these subjects we observed an unnecessary reduction in milk consumption and an insufficient dietary calcium intake.
Carroccio
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Istituto di Medicina Interna, Università di Palermo, Italy.
Montalto
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Cavera
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Notarbatolo
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D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001944:Breath Tests; D002118:Calcium / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D003903:Deuterium / Q000032:analysis; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D005260:Female; D006801:Humans; D007787:Lactose Intolerance / Q000175:diagnosis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008892:Milk
D004044:Dietary Proteins; D003903:Deuterium; D002118:Calcium