I have recently rewritten my handout on Lactose Intolerance designed for
health professionals. As this is currently topical on the LACTNET I thought
that I would post it. I would be grateful of your comments.
Laureen Lawlor-Smith
South Australia
LACTOSE INTOLERANCE



Lactose intolerance has become a popular diagnosis for irritable babies in
the Australian community. It is an overdiagnosed condition leading to
unnecessary weaning of breastfed infants with no improvement in their
irritable behaviour. It is rare before the age of three years unless there
is some damage to the small intestine (1).

Lactose is a disaccharide and is the main form of carbohydrate in all
mammalian milks. It comprises 7% of mature human milk. Lactose production
in the breast occurs independently of dietary changes. Altering the amount
of lactose in the maternal diet does not alter lactose production in the
breast. It is present at a constant level throughout a feed and throughout
the day.

Lactase, an enzyme located in the brush border of the small intestinal
mucosa breaks lactose down into glucose and galactose which are then
absorbed. Any lactose which is not absorbed will  pass through undigested
into the large bowel. This may have several consequences:

1.      Water is drawn via osmosis into the large bowel.

2.      Bacteria ferment the lactose producing:

short chain fatty acids including lactic acid which can be absorbed and
used for energy
gases such as carbon dioxide, methane and hydrogen some of which is
excreted through the lungs (giving rise to a positive breath hydrogen test)

3.      Stools are therefore:

liquid because of extra water
acid because of unabsorbed fatty acids
frothy because of unabsorbed gases
positive for reducing substances because of unabsorbed lactose


Lactose Intolerance is divided into the following categories:

1.      Congenital Alactasia or hypolactasia This is an extremely rare condition
except in Scandinavian countries. Babies with this condition do not gain
weight and are dehydrated and extremely unwell.

2.      Primary acquired or lactase non-persistence. This is an age related
condition and usually occurs after weaning and before the age of six years.
This affects approximately 70% of the world's population and 10% of
Australia's population overall (1) .

3.      Secondary acquired or lactase non-persistence occurs as a result of
damage to the small intestinal mucosa due to for example gastroenteritis,
cows milk protein intolerance or coeliac disease.

Incomplete absorption of lactose in normal infants in response to usual
feeding patterns is known as functional lactase deficiency. This has been
shown to be common in the first week of life  and may persist up to five
months of age (2) . Moore et al (3) demonstrated that 66% of normal infants
at six weeks of age and 60% at three months of age had  positive breath
hydrogen tests. The results were similar after human milk and lactase
containing formula (66% versus 72% at six weeks, 61% versus 78% at three
months). Miller et al (4) found that breath hydrogen excretion in breastfed
infants varied significantly within the same day and on different days and
therefore questioned the usefulness of breath hydrogen testing as a
clinical tool for the diagnosis of lactose intolerance. Similar percentages
of infants could be expected to have stools positive for reducing
substances. The usefulness of testing for reducing substances in the
diagnosis of lactose intolerance is therefore also highly questionable.


Management

1.      Functional Lactase deficiency

        This condition describes a thriving breastfed baby who has multiple loose
watery stools positive for reducing substances. The infant may be irritable
and may pass flatus frequently.
Ensure that the infant is thriving
Reassure the parents of the benign nature of the condition and that it is
likely to settle spontaneously with time.
Low fat feeds result in rapid gastric emptying (5) leading to large
quantities of lastose being presented to the small intestinal brush border
for digestion. Thus the ability of lactase to digest the lactose may be
overwhelmed. The amount of fat being consumed at any feed should therefore
be maximised to delay gastric emptying. This can best be achieved by
optimising hind milk intake. This can be achieved by:
Optimising positioning and attachment to ensure adequate breast emptying .
Encouraging the infant to finish the first breast before being offered the
second breast. One study (6) demonstrated that this management strategy
resulted in partial or complete resolution of symptoms in 79% of infants
with this problem.
Try spacing feeds. Aim for three hours between feeds. If the baby demands
again in less than this time offer the "empty" breast again.
Lactaid TM drops are of no proven scientific benefit in the management of
this problem.

2.      Secondary acquired lactase non persistence

This is treated by the introduction of a lactose free formula to the
infant's diet. Depending on the severity of the illness partial
breastfeeding may still be possible. If the infant has recently had
gastroenteritis average recovery time for the brush border lactase enzymes
is four weeks. ( up to eight weeks in the first three months of life and as
little as one week in infants over eighteen months) Weekly challenges with
breastmilk should be attempted until it becomes tolerated.

References


1.      Davidson GP, Lactase deficiency diagnosis and management. MJA 1984;Sept
29: 442-444
2.      Barr RG, Hanley J, et al. Breath Hydrogen excretion in normal newborn
infants in response to usual feeding patterns: Evidence for "functional
lactase insufficiency" beyond the first month of life. The Journal of
Pediatrics April 1984: 527-533
3.      Moore DJ, Robb TA, Davidson GP. Breath hydrogen response to milk
containing lactose in colicky and noncolicky infants. The Journal of
Pediatrics Dec. 1988:979-984
4.      Miller JB, Bokdam M, McVeagh P, Miller JJ. Variability of breath
hydrogen excretion in breast-fed infants during the fist three months of
life. The Journal of Pediatrics. Sept. 1992:410-413
5.      Anon. Milk fat, diarrhoea and the ileal brake. Lancet. 1986;i:658
6.      Woolridge MW, Fisher C. Colic "overfeeding", and symptoms of lactose
malabsorption in the breast-fed baby: A possible artifact of feed
management? Lancet. Aug 13 1988. 383-384