Abstract:
Availability of data on dietary patterns and food composition is fundamental to decision making in all nutrition-related programmes and policies. Data onmineraland heavy metal concentrations of foods and blood have been found useful in risk assessment of consumers. Currently, there is lack of quality data especially on mineral contentsof Nigerianfoods to compile the National Food Composition Table. Also, limited data exist on heavy metal concentrations infood and blood samples of Nigerians. This study was conducted to evaluate dietary patterns, mineral and heavy metal concentrations in food and blood samples of selected adults in Ogun State and Federal Capital Territory (FCT), Abuja.
A cross-sectional comparative study design with five-stage sampling technique was used to randomly select 2,027 adult participants from fivesub-locationseach in Ogun State (n=1,044) and FCT, Abuja (n=983). A pre-tested, structured, interviewer-administered questionnaire on food frequency was used to obtain information from all participants.Two non-consecutive 24-hour dietary recalls were collected from 386 and 349 (about one-third) participants from Ogun and Abuja, respectively. Adapted Food Processor software was used to estimate mineral and heavy metal daily intakes. Food items were purchased as consumed from food vendors selected by systematic random sampling within the ten sub-locations. A total of 605 food samples were analysed for eight minerals: potassium, sodium, calcium, magnesium, copper, manganese, iron and zinc using flame atomic absorption spectrometer, while 205 of the samples were analysed for heavy metals: cadmium and lead concentrations using graphite furnace atomic absorption spectrometer (GFAAS). Blood samples were obtained by cubital venepuncturefrom336 adult volunteers from both locations and analysed for copper, zinc, iron, chromium, nickel, manganese, cadmium and lead using GFAAS. Data were analysed using descriptive statistics and t-test at α0.05.
The most frequently consumed foods (> four times weekly) were: staples – Rice (49.0%), Maize pap (27.2%), Garri (17.6%); major protein sources – fish (55.6%), beef (37.8%) and milk (30.1%); fruits – orange (29.6%), water melon (6.7%) and banana (5.7%); and vegetables – Ewedu (17.4%), Ugu and Soko (13.8% each); which were slightly different at the two locations. Participants’ daily mineral intakes (mg/person/day) were 1968.6±783.9, 2747.4±1065.2, 334.3±169.0, 389.3±131.5, 2.8±1.0, 3.7±1.7, 23.4±8.2 and 8.7±3.4 for potassium, sodium, calcium, magnesium, copper, manganese, iron and zinc while cadmium and lead were 5.3±4.2 and 64.6±46.8μg/person/day, respectively;Ogun participants hadsignificantly higher intakes. Range of mineral concentrations in food samples were 2.9–1540.0, non-detectable (nd)–1580.0, nd–564.0, nd–451.0, nd–4.0, nd–3.9, 0.2–14.9 and nd–13.2mg/100g for potassium, sodium, calcium, magnesium, copper, manganese, iron and zinc while cadmium and lead were nd–6.3 and nd–64.2μg/100g, respectively. Serum copper, zinc and iron were 107.6±34.7, 100.3±37.8 and 95.9±40.3μg/dL, respectively with no significant difference between the two locations. Chromium, nickel, manganese, cadmium and lead were not detectable in participants’ blood.
The participants’ dietary patterns, minerals and heavy metal concentrations in the food and blood samples were within recommended levels at both locations. These indicate the safety of foods consumed in Ogun State and Abuja.
