Assessment of serum calcium in relation to dietary calcium intake in a rural population in Cameroon ()
1. INTRODUCTION
Calcium is one of the main electrolytes in body fluids. In the body, 99% of calcium is found in bones for the mineralization of bones [1]. The remaining 1% is found in body fluids where it is important for neuromuscular excitability, cardiac activity, blood coagulation and membrane permeability [2,3]. Calcium circulates in plasma in two forms: calcium bound to albumin and free ionized calcium. Serum calcium ranges from 8.8 to 10.4 mg/dl (2.2 to 2.6 mM) in healthy subjects. It comprises free ions (51%), protein-bound complexes (40%), and ionic complexes (9%) [4]. Ionized calcium has a normal value of 4.5 - 5.5 mg/dl (1.1 - 1.4 mmol/L). This value is usually affected by a number of factors including parathyroid hormone and calcitonin secretion, dietary intake and conditions like osteoporosis. Bone mineral content increases throughout childhood [5], peaks in adolescence [6], remains relatively constant in early/late adulthood
[7], and declines in old age. Dietary intake and absorption are essential to provide sufficient calcium to maintain healthy body stores. Approximately 30% of dietary calcium ingested in a healthy adult is absorbed by the small intestine. Calcium absorption is a function of active transport that is controlled by 1,25(OH)2D, which is particularly important at low calcium intakes, and passive diffusion, which dominates at high calcium intakes. Typically, at normal calcium intake, 1,25(OH)2D-dependent transport accounts for the majority of absorption, whereas as little as 8% to 23% of overall calcium absorption is caused by passive diffusion [8]. Because almost all dietary calcium intake is absorbed from the upper intestine, frequent meals or oral supplements promote net calcium absorption. The bioavailability of dietary calcium can be enhanced. Aluminum hydroxide, which binds dietary phosphate [9], when taken in excess leads to hypercalciuria from increased calcium absorption [10].
The people of the rural population under study live on yams as their main source of food. The population of this area is made up of elderly people due to rural-urban migration of the young and middle age adults in search for greener pastures. These people frequent the hospital due to pains in their muscles and bones.
2. MATERIALS AND METHODS
2.1. Sample Size
A study of 55 cases with age range from 38 - 77 years and belonging to both genders was conducted on “serum calcium in relation to their diet” at a district hospital. The study was carried out from April to May 2013.
2.2. Data Collection
Patients who were registered to the laboratory for serum calcium test responded to questionnaires from the researcher. The questionnaires were filled face to face with the respondents by the researcher and one assistant. It included information on usual diet intake and physical wellbeing of the respondents.
For the question on usual diet, the responses were categorized into 1) yams only 2) yams with meat or fish 3) yams, meat or fish and other milk products.
For questions on the physical wellbeing, responses were categorized into 1) physically fine 2) mild body pains 3) serious body pains.
2.3. Statistical Analysis
Statistical analysis of data generated was done with statistical package for social sciences (SPSS). The data was analyzed using Analysis of Variance (ANOVA). P < 0.05 is considered significant.
2.4. Estimation of Serum Calcium
Venous blood was collected in plain vacutainers and serum was immediately separated by centrifugation. The serum samples were then stored at 4˚C and analyzed within 24 hours.
3. RESULTS
Over a period of one month, 55 cases were analyzed for serum calcium levels. The age group of the cases ranged from 38 - 77 years with a males-to-females ratio of 3:8. There was an increase in abnormality of calcium levels with age shown on Table 1. From the ratio of males to females as shown on Table 2, serum calcium abnormality is higher in females than in males. Osteoporosis was the most common comorbid condition followed by muscle spasm and tetany as seen on Table 3. From the responses shown on Table 4 the people of this area live sorely on yam produce and rarely on meat, fish and other milk products. Table 5 shows the recommended calcium level for various age groups. From the responses of the people in this area as seen on Table 4, there is no doubt that their calcium is not within the recommended levels since they don’t get dietary supplements.
4. DISCUSSION
Figure 1 shows that abnormality in serum calcium increases with age. This confirms the fact that elderly peo-