Introduction

Pregnancy induces a wide variety of anthropometric, physiological and biochemical changes (₁, ₂, ₃) that requires close monitoring and most of the time nutritional supplementation. Thiamin (Vitamin B₁) is one of the four B vitamins essential in the citric acid cycle and therefore in energy-yielding metabolism (₄). It is well established that thiamine requirements are increased during pregnancy and lactation. Increased thiamine requirements during the third trimester of pregnancy are generally thought to result from sequestration of the vitamin by the fetus and placenta (₅). For example, concentrations of thiamine and other water soluble vitamins are 2-fold higher in umbilical cord blood than in maternal blood (₆). Pregnant women and young children are at higher risk of thiamine deficiency (₇).

The classical syndrome caused primarily by thiamine deficiency in humans is called beriberi which is characterized by neuritis in the lower extremities, often with muscle atrophy, poor coordination, and eventually paralysis (₈). The benefit of thiamine in prevention and treatment of beriberi is uncontested (₉, ₁₀). Thiamine deficiency is common where highly polished rice is the major staple food and where other primary sources of thiamine (Meat, fish and legumes) are in short supply (₇). Deficiency is compounded where local diets include foods such as fermented fish (₇) and tea leaves which contain antithiamine factors (₁₁, ₁₂).

Derrick (₈) reported that “beriberi” presentation also depends on the association with other vitamin deficiencies. Because thiamine is a major factor in the metabolism of glucose, it has been long known that ingestion of simple carbohydrates, processed in the body mainly to glucose, automatically increases the need for dietary thiamine. Thus, high calorie malnutrition is commonly associated with relative thiamine deficiency, irrespective of its fortification in food substances therefore an increase of dietary carbohydrate intake caused a decrease of plasma and urine levels of thiamine (₈).

In the present study we hypothesized that serum thiamine level will be the same among pregnant and non-pregnant women, and between educated and non-educated women.

Materials And Methods

Demographics

Estimation of Thiamine from Blood Serum

Ethical Consideration

Statistical Analyses

Results

The women (n = 179) ranging from 16-50 years were use for this study. Out of these, 72 pregnant women with a mean age of 24.95 ± 5.19 for second trimester, 56 pregnant women with a mean age of 27.86 ± 5.93 and 51 non-pregnant women with a mean age of 27.04 ± 6.04 served as control.

Thiamine levels in the three study groups (control, second and third trimester) are presented in Fig. 1. Using one way analysis of variance the result show a significant decrease (P<0.001) from the control (47.90 ± 25.93) to third trimester (27.09 ± 10.69). Tukey post hoc test showed that there was statistical significant difference between control, second and third trimester (P<0.05), however there was no statistically significant difference between second trimester and third trimester P>0.05.

The pregnant women were categorised according to their level of education (Fig. 2). The thiamine level in the pregnant women who have tertiary education is significantly higher (P<0.001) from the others. The control and pregnant women were categorised on the level of their education (Fig. 3). Thiamine levels in the control was significantly higher (P<0.001) than thiamine level in the pregnant women who are well educated. Also there was a significant difference (P <0.001) between control and pregnant women, when they were categorised according to age group (Table 1).

Figure 1

Figure 1: Means of serum thiamine level in pregnant and non-pregnant women. Control is significantly different from second and third trimester groups * P

Figure 2

Figure 2: Thiamine level according to level of education. Women with tertiary education showed significantly higher thiamine level than the other group *P 0 001.

Figure 3

Figure 3: Thiamine level according to level of education and pregnancy in women. Control is statistically significantly different from pregnant non-educated and pregnant educated women * P

Figure 4

Table 1: Mean thiamine level according to age

Discussion

Previous studies (₅, ₇, ₁₄) reported low thiamine level in pregnancy. This present study also shows that thiamine level is reduced significantly towards delivery (P<0.001). Thiamine requirements are increased during pregnancy and lactation, increased thiamine requirements is as a result from sequestration of the vitamin by the fetus and placenta (₅). Food and Nutrition Board, Institute of Medicine (₁₅) gave required daily allowance (RDA) of thiamine for pregnant women to be 1.4mg/d. but these recommendations is only for a biochemically healthy individual (₈). Report of high incidence of thiamine deficiency during pregnancy and lactation have previously been reported in India, Malaysia, Ghana and Thailand where stable diet of milled or polished grains instead of brown rice is been consumed, and also the consumption of food rich in thiaminases was also implicated (₅). In Nigeria thiaminase was found in pupae of an African silkworm that is consumed as a source of protein (₁₆).

The low thiamine level among pregnant women in Zaria may be attributed to the fact that there is high ingestion of simple carbohydrate in all its different forms. Derrick (₈) reported that ingestion of simple carbohydrate results into high calorie malnutrition, and because thiamine is a major factor in the metabolism of glucose, there is an automatic increase in the need for dietary thiamine. Thus high calorie malnutrition is commonly associated with relative thiamine deficiency irrespective of its fortification in food substances (₈).

This present study also shows that thiamine level has significant relationship or association with educational level of the pregnant women (P<0.001), with the women who have had tertiary education or who are in tertiary institutions having higher thiamine level than those who have had secondary, primary or who have never received any formal education respectively. But however when the pregnant women were categorised into educated, non educated, the control group still had higher values than the pregnant educated, this is due to the fact that the pregnant women though educated still need supplementation of thiamine, because of the increase demand of thiamine in pregnancy. But however parity had no effect on thiamine level in this study, probably due to size effect.

When the women were categorised according to age group, control still had significantly higher thiamine level over the pregnant women (P<0.001). This shows that irrespective of age there is an increase demand of thiamine during pregnancy.

Conclusion

In this part of the country where diet is loaded with simple carbohydrate, there will be need for fortification of thiamine because of its biochemical association with glucose metabolism. It is also well established that thiamine requirements are increased during pregnancy and lactation. Considering the fact that women, especially those in low socioeconomic class have low nutritional standards and their carbohydrate intake is high, it will become necessary for supplementation of thiamine in their diet. But in general irrespective of age, educational level or socioeconomic status, there is a need for vitamin supplementation especially thiamine for pregnant women, because vitamins and minerals are very important in the oxidative processes of the body, since these processes requires oxygen, fuel and catalyst for their normal functions.

Recommendations

This study was able to take only a cross-sectional study. A longitudinal study can be conducted involving more pregnant women and from more hospitals so as to establish the fact that pregnant women in Zaria, Nigeria have low thiamine level, because there is an urgent need for adequate thiamine supplementation in high-risk population, of which Zaria is one. The cultural stigma associated with consumption of brown rice which is considered to be a food for the poor should be discouraged and a return to traditional brown rice is highly recommended. There is also a need to ascertain the effect of low thiamine level on birth weight. There is a need also to conduct a study of thiamine level in lactating mothers and its effect on the babies.