This study was done in August, 2012 in Mgeta and Njombe rural areas of Tanzania for the
purpose of assessing the prevalence of lactose intolerance and its severity in relation to milk
intake so as to create awareness on how people can cope with the problem without rejecting
dairy foods completely. The small-holder farmers in Mgeta have been dealing with dairy-goat
keeping based on the Norwegian breeds while the farmers in Njombe have been keeping dairy
cows for more than 20 years now. The study was based on the cross-sectional survey whereby
the household milk intake was assessed among the dairy-goat / cow keepers and the non-keepers.
The status of lactose intolerance in the study areas was evaluated by assessing the typical
symptoms following milk intake, and the quantity and form of milk that was associated with the
intolerance. Pearson-Correlation test was used to determine whether the quantity of ingested
milk influenced the severity of the symptoms among the lactose intolerant subjects. The severity
of lactose intolerance was defined as the time taken for the symptoms to subside following milk
intake among the lactose intolerant subjects. A linear relationship was assumed to exist between
the quantity of ingested milk (an independent variable) and duration of the symptoms severity (a
dependent variable).
Both in Mgeta and Njombe lactose intolerance manifested symptomatically following milk
intake by the intolerant people; the typical symptoms experienced were nausea, vomiting,
abdominal cramps, bloating and diarrhea. In Mgeta, only 1 person (10%) of the lactose intolerant
subjects had the intolerance with fermented goat’s milk while 9 (90%) experienced the
intolerance with fresh or boiled-hot goat’s milk. Generally, the lactose intolerant subjects in
Njombe experienced the intolerance symptoms whenever they took cow’s milk as fresh, boiledhot,
fermented, and as a cooking aid or mixed with tea / coffee. According to the Pearson’s
correlation test, the severity of lactose intolerance was found to be correlating positively with the
quantity of ingested milk both in Mgeta and Njombe with (P=0.005; R=0.807) and (P=0.000;
R=0.860) respectively at 99% CI. Cow’s milk related to the severity of lactose intolerance more
than goat’s milk. This is due to the observation that, a larger volume of ingested goat’s milk (586
MLs) was found to associate with the symptoms persistence for a shorter time (233 minutes) as
compared to ingested cow’s milk where a smaller volume (467 MLs) produced the symptoms
that persisted for a longer time (237 minutes).iii
The prevalence of lactose intolerance in Mgeta and Njombe were 2% and 3% respectively.
Based on the observed prevalence both in Mgeta and Njombe, lactose intolerance seems to pose
no serious threat that may compromise milk intake now and in future. Putting these findings in
perspective, the keeping of dairy animals (goats and cows) remain a potential contributor in
fighting hunger and malnutrition in the country through increasing consumption of animal based
protein sources (milk and meat) and income generation by selling off the surplus production
which subsequently can entitle people to access balanced diet adequately.
Among the dairy-goat keepers in Mgeta, the household milk intake was approximately 6 litres
per week – equivalent to 200 MLs per person per day. The non dairy-keeper households in
Mgeta were consuming about 4 litres per week – equivalent to 100 MLs per person per day. A
T-test showed a significant difference in weekly milk intake (MLs) between the dairy-goat
keepers and the non-keepers in Mgeta (P=0.004; 1480 (MD) ± 498 (SE)) at 95% CI. On the other
hand, milk intake in Njombe was quiet low; approximately 1 litre and 0.4 litre per household per
week for the dairy-cow keepers and the non-keepers respectively. This was equivalent to the
daily intake of 29 MLs and 11 MLs per person among the dairy-cow keepers and the nonkeepers
respectively. Also, there was no significant difference in weekly milk intake between the
dairy-cow keepers and the non-keepers in Njombe.
Conclusively; the positive correlation between the quantity of ingested milk (with lactose
therein) and the severity of lactose intolerance means, the more the lactose dose to be ingested,
the more severe lactose intolerance is likely to manifest among the lactose intolerant people. This
relationship provides a potential coping mechanism whereby reducing a volume of milk (lactose
dose) to be ingested by the lactose intolerant people mitigates or eliminates the problem. Taking
milk with other foods as part of a daily meal and preference to fermented milk can be added
advantage in coping with lactose intolerance. Owing to the observed small number of lactose
intolerant individuals which were 10 and 17 for Mgeta and Njombe respectively, there is a
possibility the findings regarding lactose intolerance might have occurred by chance; thus further
studies are recommended. People in the study areas seemed to have good perception on milk and
the intake depended on dairy-keeping, household income and decision making in the families.
Milk intake in Mgeta was found to be influenced by dairy-goat keeping and probably household
power distribution from which women were postulated to play a significant role on a better use iv
of milk. On the other hand, milk intake in Njombe was very low because the households were
selling most of the milk to the dairy company in the town; this priority could have possibly been
attributed by poverty (increased need for cash) and somewhat low involvement of women in
decision making. What is required in stabilizing milk supply and consumption in the country is
to encourage keeping of dairy animals (mainly cows and goats) and educating the citizens on the
health / nutritional benefits of milk. This should go together with poverty eradication strategies
and provision of knowledge among the lactose intolerant people or the maldigesters on how they
can cope with the problem without ruining their recommended intake of milk and dairy products.