Geophagia, the practice of eating earth or soil-like materials such as clay, is a behavior observed in animals and humans, particularly in rural or preindustrial societies among children and pregnant women. This practice, also known as geophagy, involves the consumption of geophagic clay.
In Nigeria, geophagia is often associated with clay consumption, with pregnant women being frequent consumers. The act of eating clay is common in developing countries because most pregnant women eat clay as an appetite suppressant and it is also observed in anorexia nervosa. This article delves into the composition of Nigerian edible clay, its potential health implications, and the cultural context surrounding its consumption.
Geophagy
Geophagia: A Global Perspective
Geophagia, the consumption of earth, including soil and clay, is a practice observed worldwide. Pica is a general term which refers to the repeated ingestion of non-food items normally insatiable and leads to its compulsive consumption [1]. Pica in humans has many different subgroups and each of these subgroups is defined by the substance ingested. Based on the items consumed [2], identified thirty-six (36) types of pica which consist of both non-food and food items. Several forms of pica exist and some classifications include amylophagia (starch), coprophagia (faeces), geophagia (dirt, soil and clay), hyalophagia (glass), lithophagia (stones), pagophagia (ice), etc. Furthermore, pica according to other researchers [2-4] include paint, hair, plaster, live wasps, chalk, vinegar, grass, and many others.
It is characterized as a form of pica (a term that comes from the Latin word magpie which has indiscriminate eating habits) [6]. Human geophagia may be related to pica, a psychological disorder characterized by an appetite for substances that are largely nonnutritive, such as ice (pagophagia); hair (trichophagia); paper (xylophagia); stones (lithophagia) or soil (geophagia); and chalk.
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Areas in Africa where such practices are in existence include; South Africa, Nigeria, Cameron, Uganda, Tanzania, Ghana, among many other areas of the continent.
In Ghana, processed kaolin (white clay) ready for consumption is known as Ayilo (Ga), Agatawe (Ewes), Hyire (Akan) and several other names in other dialects. It is mostly mined in parts of the Volta Region, especially Anfoega, where the freshly mined clayey soil is molded into lumps, oven-baked and distributed to markets across Ghana.
The craving for clay, is especially common in pregnant women and it is consumed by different people for different reasons. Most people consume it for its peculiar taste and smell and become addicted to it later on thus preventing them from avoiding it if need be. Kaolin is also perceived to possess some health benefits, it is believed to contain certain mineral elements which could be beneficial to human health, and some spiritual connotations are linked to its intake.
Some of these beliefs are; an antidote to diarrhoea, stomach discomfort, nausea and other discomforts associated with pregnancy [9]. Geophagy has some economic implications on some families since pregnant women save some monies for its purchase which may be disadvantageous to people with low income. An average of 230 grams of baked clay cost GHS 40 ($9.00) and the price vary with location [10] in Ghana.
The study area where this research was concluded was in Ho, the capital city of Volta Region. The Kaolin samples were purchased from Anfoega in the Volta Region. Anfoega is situated in Dayi, Volta, Ghana. Its geographical coordinates are 6° 53' 0" North, 0° 18' 0" East and its original name (with diacritics) is Anfoega Akukome [11].
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Calabash Chalk: A Specific Type of Edible Clay
Calabash chalk is identified by different names such as calabar stone (English), la craie or argile (French), mabele (Lingala in Congo), nzu (Igbo of Nigeria), ndom (Efik/Ibibio Nigeria) eko (Bini/Edo Nigeria). Calabash chalk is found predominantly in Nigeria and other West African communities.
Calabash chalk is a naturally occurring material composed of fossilized sea shells. However, it can be prepared artificially by combining clay, sand, wood ash and even salt. There are different views concerning the components of calabash chalk, the consensus being that the major component is aluminum silicate hydroxide. This comes from the kaolin clay group, making Al2Si2O5(OH)4 a possible formula for calabash chalk. Calabash chalk is also known to have very high concentrations of lead.
The practice of eating calabash chalk is observed by both sexes and different age groups of people of African descent, for the purpose of pleasure. There are several reports regarding the health risks of consuming calabash chalk including; the alteration of the normal concentration of hemoglobin, red blood cell counts and erythrocyte sedimentation rate. Another possible side effect of eating this geophagia is the alteration of growth rate and de-mineralization in the femur bone.[5] Other reports suggest that calabash chalk also causes numerous gastrointestinal disorders such as nausea, ulcers and gastritis.
Geophagia, the consumption of earth, including soil and chalk, is a practice observed worldwide.
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Mineral Composition and Potential Health Risks
Kaolin can be industrially mined; it is usually dug out from the deep parts of the earth crust. It contains chemical elements such as Aluminium, Arsenic, Boron and Nickel which can be potentially harmful to humans [7].
Many research works have been carried out on the evaluation of essential elements in geophagic clay for effective curative of both skin and intestinal disorder among pregnant women, and recommended pharmaceutical regulatory agency to effectively put control on its consumption, [1, 14,15,16]. The metal and mineralogical characteristics of clay in many parts of Nigeria such as Ibadan, Benin, Calabar and other Southern parts of Nigeria, [2, 4, 5, 9] as well as some of the other parts of Africa have been carried out with a view to finding the total metal content and possible health implications on their consumer [17,18,19].
Result showed that for the Calabar clay, it was relatively enriched with Zn, Pb and other potentially harmful elements, using inductively coupled plasma mass spectroscopy (ICP-MS) and the findings showed that these elements may probably be the cause of high prevalence of hypertension, cardiac failures and gastrointestinal problems within the study areas, [5]. Similar results have been observed and recommendations were given for communities in Free State province of South Africa, [20].
Recently, [16] carried out in detail the mineralogical, geochemical and health impacts of that earth materials consumed by humans in Vhembe district in Limpopo province, South Africa and found out that there are essential elements like selenium in them that could be extracted for immune booster for HIV patents, [16]. It was therefore recommended that pregnant women and children that consume this clay material without control should seek protection against gastrointestinal problem and toxin because of the possible high bioaccessibility of some potentially harmful elements like Hg, As, Pb and Zn found to be high in both in their intestine and stomach, [16].
The works of [22, 26,27,28,29] further reported the relevance of carrying out bioaccessibility and bioavailability of geophagic clay in the human internal system in order to know the relative health risk that such clay consumption poses to the human beings. Issues relating to frequency of consumption, which brings about gradual build-up over time of these elements in the vital organs of the body, the nature of the chemical species and oxidation state of these harmful elements, soil pH, stomach and intestinal pH, soil-to-solution ratio and fasting condition can increase health risk.
Exposure of lead to pregnant and breast-feeding women is of higher risk, as reported by [33, 34]. This is because it was observed that the metal easily crosses the placenta and migrate (absorbed) into breast milk even at a relatively low exposure, causing adverse effects on child’s neurodevelopment and physical growth.
Similarly, [11] studied some major elements as well as toxic metal concentrations in clay in Volta region of Ghana, using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The elements were iron (Fe), copper (Cu), zinc (Zn), potassium (K), magnesium (Mg), sodium (Na), arsenic (As), manganese (Mn), lead (Pb) and nickel (Ni). This clay was found to be consumed by pregnant women in the study area. The results showed that Fe, Cu, Zn, K, Mg, Na, As, Mn, Pb, and Ni, recorded 1.38, 2.40, 7.74, 4.01, 13.24, 13.76, 1.63, 4.72, 0.53 and 1.85, respectively, in µg/kg. Harmful elements such as As, Mn, Pb and Ni were further compared with World Health Organization [35] threshold recommendation at µg/kg at 60 kg body weight per day of 3.0, 4.9, 3.0 and 5.0, respectively. From the result, [Kortei el al., 2020] opined that the cumulative effect of the consumption of the clay may cause detrimental effect on the foetus of the unborn child. Hence the need for proper evaluation in other to know the places wher thes clays are mined and sold.
In Nigeria, most works that have been carried out, which have only been done by first sampling from the market places where most of the clays are sold [2, 4, 22] as well as determination of total metal content in the evaluated clay. Till date, no known published work has been carried out on the total metal content, mineral composition determination in the deposits where these clays are mined, processed and sold for consumption in this study area.
The geology of an area has a direct influence on the chemical composition of the soils. All the geophagic clay materials are hydrated silicates of either Al, (Na and Ca), (Al and Mg), or/and (Mg and Fe). The concentration levels of Na, Al, Ca, Fe, Mg, Cu, and Zn are tolerable and apparently could serve as a veritable source of mineral nutrients deficient in the human body.
An assessment of the level of contamination of heavy metals on the basis of the index of geo-accumulation (I(geo)) shows that Cr, Cu, Zn, Co, and Ni (all with I(geo) < 1) did not contaminate the clay materials. On the contrary, they are extremely contaminated by As, Cd and Se (I(geo) = >5), and are moderately to strongly contaminated by Pb and Sb (I (geo) = 2-3). In terms of health risk assessment, the presence of heavy metals such as As, Cd, Pb, Se, and Sb with a health risk index (HRI) >1, renders the geophagic clays unsafe for human consumption. Similarly, Al, Fe, and Na are in excess in the clay (HRI ⋙ 1) posing serious human health risks. Thus, the ingestion of geophagic clay materials by pregnant women and children when it contains heavy metals like Pb, As, Cd, Se, and Sb poses the risk of some medical disorders and should therefore be considered a public health problem.
Volta Region, Ghana Study: Geophagy Among Pregnant Women
A study conducted in the Ho municipality of Ghana revealed a geophagy prevalence of 48.4% among pregnant women. The study employed a cross-sectional convenient sampling method to sample 217 pregnant women and sellers of clay (Ayilo). A face-to-face interview was conducted to administer a structured questionnaire to respondents.
Results obtained also suggest smell and taste of the clay, influenced the consumption by these pregnant women to a large extent. Strikingly, majority of the respondents had no knowledge on the adverse health implications clay consumption had on the human body. The physiological state of pregnancy also cause many to use it to treat nausea, other accompanying discomfort and in some instances to quench their hunger. Traces of Lead, Nickel and Arsenic were found in the clay. The clay also contained pathogenic microorganisms.
Table 2 summarizes the results obtained from pregnant women who practiced geophagy. Most of the respondents, 108 (49.8%) of 217 had heard of clay (ayilo) from peers, 101 (46.5%) from family and only 8 (3.7%) from the media. Most of them 177 (81.6%) had consumed clay before. Among those who had consumed clay before, quite a moderate number 132 (74.6%) of them consumed clay once during the day. Most of them 116 (65.5%) consumed about 1 piece a day and 12 (6.8%) ate about 4 pieces a day. Those who ate it at any time they felt like were 108 (61%). Most of them, 137 (77.4%) purchased it from the stores and the rest from the market or other places. About 89 (50.3%) of them started eating clay 10-15 years ago, 20 (11.3%) of them 3 months ago and 105 (59.3%) are still eating.
Majority 81 (45.8%) of 177 pregnant women consume clay because of the smell. A moderate number of 44 (24.9%) consumed clay because of the taste. Hunger was the reason for 4 (2.3%) and 6 (3.4%) consume clay for health reason such as peptic ulcer disease treatment. Peer influence accounted for kaolin consumption in 20 (11.3%). Fifty-two (29.4%) consumed kaolin due to cravings and the desire to take clayey materials.
Among 217 pregnant women interviewed on the side effects of geophagy, most, 129 (59.4%) said they knew there was some associated side effects with clay consumption. A sizeable proportion 52 (24%) said there was no side effect. A minority 16 (7.4%) said consuming clay might have some side effects and 20 (9.2%) said they do not know the effects of clay on the human body.
One hundred and twenty-nine pregnant women who said clay had negative side effects gave some side effects they knew. A considerable proportion 76 (58.9%) said geophagy could cause anaemia, while 60 (46.5%) said it caused constipation, 2 (1.6%) said it elevated menstrual cramps. Four (3.1%) said it caused parasitic (worms) infestation. Thirty-seven (28.7%) said taking clay change the skin of your child to white during delivery. Sixteen (12.4%) said geophagy caused infertility.
Table 3 shows the associations between socio-demographic characteristics and awareness of side effects of pregnant women in the study. The age group of participants was significantly associated with awareness of side effects (χ2 = 24.027; p = 0.008). Ethnicity of the pregnant women was significantly associated with awareness of side effects (χ2 = 52.536; p < 0.001). Religion of participants was also significantly associated (χ2 = 18.138; p = 0.001). The occupation of pregnant women was equally associated (χ2 = 64.416; p < 0.001). The number of children pregnant women had was significantly associated (χ2 = 11.523; p = 0.021). Total monthly income of pregnant women was significantly associated (χ2 = 36.897; p < 0.001). Educational level had a significant association (χ2 = 31.049; p < 0.001) and the locality of these pregnant women also had significant association (χ2 = 19.754; p < 0.001).
Reasons for clay consumption among pregnant women.
Table 1: Socio-demographic characteristics of respondents
| Characteristic | Frequency (N=217) | Percentage (%) |
|---|---|---|
| Age Group | ||
| 16-19 years | 16 | 7.4 |
| 20-24 years | 52 | 23.9 |
| 25-29 years | 64 | 29.5 |
| 30-34 years | 48 | 22.1 |
| 35-39 years | 25 | 11.5 |
| 40-45 years | 12 | 5.5 |
| Ethnicity | ||
| Ewe | 197 | 90.8 |
| Akan | 8 | 3.7 |
| Ga-Adangbe | 8 | 3.7 |
| Northerner | 4 | 1.8 |
| Religion | ||
| Christian | 197 | 90.8 |
| Muslim | 16 | 7.4 |
| Traditionalist | 4 | 1.8 |
| Marital Status | ||
| Married | 148 | 68.2 |
| Single | 60 | 27.6 |
| Widowed | 4 | 1.8 |
| Co-habiting | 5 | 2.3 |
| Occupation | ||
| Self-employed | 49 | 22.6 |
| Professional worker | 60 | 27.6 |
| Office worker | 20 | 9.2 |
| Trader | 36 | 16.6 |
| Farmer | 8 | 3.7 |
| Student | 16 | 7.4 |
| Unemployed | 28 | 12.9 |
| Number of Children | ||
| None | 84 | 38.7 |
| 1-2 | 121 | 55.7 |
| 3 | 12 | 5.5 |
| Household Size | ||
| Less than 6 | 156 | 71.9 |
| 6 or more | 61 | 28.1 |
| Educational Level | ||
| No Education | 4 | 1.8 |
| Basic Education | 12 | 5.5 |
| JHS/Middle School | 97 | 44.7 |
| SHS Education | 72 | 33.2 |
| Tertiary Education | 32 | 14.7 |
Table 2: Geophagy practice among pregnant women
| Question | Response | Frequency | Percentage |
|---|---|---|---|
| How did you hear of clay (Ayilo)? | Peers | 108 | 49.8% |
| Family | 101 | 46.5% | |
| Media | 8 | 3.7% | |
| Have you consumed clay before? | Yes | 177 | 81.6% |
| How many times do you eat clay in a day? | Once | 132 | 74.6% |
| Twice | 33 | 18.6% | |
| Thrice | 12 | 6.8% | |
| Pieces of clay (Ayilo) eaten in a day. | 1 piece | 116 | 65.5% |
| 2 pieces | 49 | 27.7% | |
| 4 pieces | 12 | 6.8% | |
| What time of the day do you usually eat clay? | Any time | 108 | 61% |
| Specific time | 69 | 39% | |
| Where do you purchase your clay from? | Stores | 137 | 77.4% |
| Market/Other | 40 | 22.6% | |
| How long have you been eating clay? | 3 months ago | 20 | 11.3% |
| 6 months ago | 32 | 18.1% | |
| 1 year ago | 36 | 20.3% | |
| 10-15 years ago | 89 | 50.3% | |
| Are you still eating clay? | Yes | 105 | 59.3% |
| Have you had the cravings to eat clay during pregnancy? | Yes | 145 | 81.9% |
Table 3: Associations between socio-demographic characteristics and awareness of side effects
| Socio-demographic Characteristic | Chi-Square Value | P-value | Significance |
|---|---|---|---|
| Age group | 24.027 | 0.008 | Significant |
| Ethnicity | 52.536 | < 0.001 | Significant |
| Religion | 18.138 | 0.001 | Significant |
| Occupation | 64.416 | < 0.001 | Significant |
| Number of children | 11.523 | 0.021 | Significant |
| Total monthly income | 36.897 | < 0.001 | Significant |
| Educational level | 31.049 | < 0.001 | Significant |
| Locality | 19.754 | < 0.001 | Significant |
