Oorsig/Review
Since lactose is the major osmole in milk, anything that affects
lactose production will affect milk volume
LACTOSE MALDIGESTION/
INTOLERANCE
Lactose maldigestion is the difficulty to
digest Lactose and is very common. Lactose
intolerance is less common and is the term
used when lactose maldigestion develops into
symptoms. Lactose maldigestion happens due
to the natural decline of lactase production in
humans after infancy (for the reasons why this
happens – see sidebar in this article). The non-
persistence of Lactase in adults is normal and
therefor Lactose intolerance is the norm rather
than the exception.
LACTOSE MALDIGESTION
VS. MILK ALLERGY
Milk allergy is quite rare and is an
immunological response to the pro-
teins (caseins and whey) that occur in
milk. Symptoms include pruritis, urti-
caria, swelling, nausea and respiratory
distress. Signs usually occur within 72
hours after consuming milk.
Lactose maldigestion is the natural
occurrence of a reduced production
of lactase after infancy. As a result
undigested Lactose enters the colon
where bacterial fermentation and the
osmotic effect of Lactose causes bloat,
flatulence, diarrhoea and abdominal
discomfort.
Lactose is a sugar and is not targeted
by the immune system
When undigested lactose enters the colon, it is
fermented by colon bacteria that produce lactic
acid, acetic acid and other short chain organic
acids, plus methane, carbon dioxide and hydrogen
gas (H2). H2 is absorbed by the intestinal lining,
passed into the circulatory system and exhaled via
the lungs where increased levels can be detected.
The gas production leads to increased colonic
14
Marine mammals such as seals, sea lions and walruses
lack alpha-lactalbumin and as a consequence their milk
is lacking in lactose and has a very high fat and protein
content instead. Not only do these animals lack lactose
in their milk, they also lack the lactase enzyme that
is needed for its digestion. Feeding cow’s milk (which
contains lactose) to a baby walrus will result in severe
diarrhoea..
pressure. In addition, Lactose has a strong osmotic
effect which draws water into the colon leading
to diarrhoea. The acids lead to increased transit
time in the colon, exacerbating the problem. The
combination of these factors lead to the symptoms
which include bloat, flatulence, diarrhoea and
abdominal discomfort. The amount of lactose
that individuals can tolerate varies between
individuals. However, the severity of symptoms
is dependent on the volume of undigested lactose
that reaches the large intestine.
Some individuals retain the production of
lactase into adulthood (lactase-persistence) and
as a result can digest lactose throughout their
lives. This is more common in people of North-
European, Middle-Eastern and East-African
descent. Lactose-intolerance is much more
common in people of African and Asian descent
where the inability of adults to digest Lactose can
be as high as 90%.
The ability to digest milk into adulthood appeared
approximately 10,000 years ago as the result
of a mutation. Which seems to coincide with
the domestication of livestock. As the human
population migrated, they took the mutation with
them and through interbreeding with the local
populations, spread the mutation. Archaeological
evidence supports the fact that this mutation
spread with the introduction of domesticated
livestock as populations migrated.
It is theorised that the benefit of lactose tolerance
was most probably due to the fact that milk was
a readily available source of nutrition and liquid
during times of food and/or water scarcity. This
improved the chances of survival of populations
that could consume milk. In addition, better fed
warriors were larger and stronger than their
counterparts, which probably assisted the spread
of populations that were tolerant to lactose.
Since Lactose is associated with the water-soluble
fraction of milk, such as whey, it is removed in
the fermentation process of milk. Therefor hard