From: Jim Barron <>

> From: Robert Sleigh <>

> Subject: Re: Lactose Intolerance


> Dear All,


> I wonder what is the real basis for the frequent referral to "lactose

> intolerance".


Lactose intolerance is caused by a deficiency of *lactase*, the enzyme

necessary to digest the lactose sugar in milk. When inadequate levels

of this enzyme are present (celiacs cannot produce it due to damaged

villi) all or part of the lactose in milk reaches the gut where it is

digested (fermented) by bacteria - producing gas, diarrhea, etc.


Lactose intolerance does NOT involve a reaction to a protein in milk.




> Mothers milk contains a higher concentration of lactose than cows milk

> however all babies thrive on mothers milk.


Celiac babies on mother's milk not exposed to grains would have no

damage to their villi and be able to produce adequate lactase, so no

problems. Those who had been exposed to grains (although also

receiving mothers milk) would have their problems attributed to the

grains (correct) often without recognition that there was a secondary

effect making them inable to handle the lactose in milk (ANY milk).


I do not know, but it seems possible that the mother's milk contains

lactase as well (or rather a *precursor* of lactase).



> In tests of asians and aboriginals who historically did not include cows

> milk in their diet, they had to consume something like 2 litres (3 and a bit

> pints) of milk before they had real effects such as diarrhea. Drinking a

> 250 ml glass of milk once a day went without this effect with the test subjects.


> I can understand and accept that hypersensitive individuals could have rapid

> reactions to cows milk proteins.


> Are people really talking about "cows milk protein intolerance" when they

> say someone is "lactose intolerant"?



Absolutely not. Cows milk protein intolerance is generally an

intolerance to casein (although it may involve other proteins as well).

But if it was intolerance to lactase (which, like most enzymes, is a

protein), it would not be **cow's** milk intolerance, it would be MILK

intolerance (to ALL milk).


> Dr. Robert Sleigh

> Senior Research Scientist

> CSIRO Division of Food Science and Technology

> PO Box 52, North Ryde, NSW 2113, AUSTRALIA

> ph:+ 61 (02) 9887 8385 fax:+ 61 (02) 9887 3107