Micronutrients are vital to health as they ensure normal growth, metabolism and physical wellbeing (1, 2). Although required in small amounts, the impact of their deficiency is severe (3). Globally, more than 2 billion people suffer from micronutrient deficiencies, with the main being iron, zinc, iodine, vitamins A and B (4, 5). During pregnancy, these deficiencies which results from; lack of consumption of nutrient-dense food groups, poor understanding of the importance of a diverse diet and inefficient utilisation of available micronutrients (6, 7) can lead to a myriad of adverse maternal and perinatal outcomes including; anaemia, increased susceptibility to infectious diseases, low birth weight, preterm birth, increased risk of maternal and neonatal mortality as well as cognitive deficit in the baby later in life (2, 8).

Anaemia is a widespread public health problem that has significant consequence for human health, social development, and economic growth (9–11). According to the World Health Organization (WHO), anaemia is a condition in which the haemoglobin concentration within the red blood cells are lower than normal and consequently their oxygen carrying capacity is insufficient to meet the physiological demands of the body (12, 13). This results in symptoms such as; body weakness, fatigue, dizziness, palpitations and shortness of breath (13, 14). In 2019, the prevalence rates of anaemia was estimated at 29.9% among women of reproductive ages (WRA) and 36.5% in pregnant women (15). Though preventable, in pregnancy it is still one of the leading causes of maternal and neonatal morbidity and mortality (16, 17). Apart from nutritional deficiencies of which iron deficiency is the most prevalent cause of anaemia, other conditions such as folate, zinc, vitamin A and B deficiencies, chronic inflammation, infectious diseases and inherited haemoglobin disorders can as well lead to anaemia (12, 18, 19).

Over the past decade, awareness for anaemia and its consequences for maternal and infant health has increased. For instance, in 2012, the 65th World Health Assembly (WHA) approved global targets for maternal, infant and young child nutrition with a commitment to reduce to half the prevalence of anaemia among WRA (15–49 years) by 2025 (20, 21). Ensuing this, the WHO and United Nations Children’s Fund (UNICEF) proposed extending this target to 2030 to align with the United Nations (UN) Sustainable Development Goals (21, 22). With this in mind, Cameroon has been committed to curb the burden of maternal anaemia through malaria prophylaxis and haematinic supplementation (16). Despite efforts, anaemia prevalence rates have not changed over the years as it is still a severe (≥ 40%) health problem in WRA (23, 24). An explanation to this high prevalence rates could be an underestimation of the role of dietary micronutrient inadequacy on anaemia. Besides, data on micronutrients are limited in the study area and are thus needed, to design and implement public health programmes targeted at reducing anaemia. Hence, this study aimed to investigate intake of dietary nutrients and its effect on maternal haemoglobin levels in the Mount Cameroon health area.

In Cameroon, anaemia prevalence among women is still severe (≥ 40%) (16, 24, 25). This high prevalence rate may represent significant constraint for achieving the Global Nutrition Target endorsed by the World Health Assembly of halving anaemia prevalence among WRA by 2025 (20). This study therefore aimed to evaluate dietary micronutrient intake and their effect on haemoglobin levels of pregnant Cameroonian women.

In order to reduce the risk of anaemia during pregnancy, the WHO recommends a daily oral dose of 60 mg of iron along with 400 μg of folic acid throughout pregnancy and as part of the routine antenatal care services (37). In Cameroon, iron supplementation is the main strategy for anaemia control and prevention (16, 38). In addition, several studies have shown that iron-folic acid uptake during this critical period prevents maternal anaemia while reducing the risk of preterm labour, low birthweight, premature delivery, postpartum haemorrhage (39–41). The observed anaemia prevalence rate (40.9%) among study respondents in the study area despite uptake of iron-folic acid (71.5%) might be due to poor adherence, an aspect this study did not assess. Poor adherence to iron supplements may be as a result of inadequate supply of iron tablets, poor utilisation of prenatal health-care services, gastrointestinal discomfort accompanied with the drug, inability to purchase the tablet, forgetfulness, poor counselling by health care providers regarding the usefulness of the tablet as well as maternal knowledge and beliefs surrounding the tablet (42–44). Besides, this study further showed that combine uptake of iron-folic acid with a diet rich in haem iron or vitamin A food groups is more efficient in reducing the burden of anaemia than iron-folic acid taken alone.

Although diet holds great importance for maternal and neonatal health, inadequate proportions are often consumed most especially by women residing in low-and-middle income countries and study participants in the Mount Cameroon area were no exception (89.6%) (25, 45, 46). According to the WHO, the most common micronutrient deficiencies are; iron, vitamin A and iodine deficiencies (2, 47). In this study, 86.2% of the women consumed foods rich in iron specifically haem iron a day before the survey. Dietary iron is present in two forms that is haem iron, which is obtained from animal products such as meat, fish and poultry whereas non-haem iron is obtained from cereals, fruits and vegetables (36, 48, 49). Furthermore, it was observed in this study that consumption of haem iron was associated with increased haemoglobin levels of pregnant women. This finding is in line with observations from Jakarta (50), Ethiopia (51) and Pakistan (52). The increased haemoglobin levels among women who consumed meat, fish and poultry might be due to the fact that, foods rich in haem iron are absorbed from the gut with greater efficiency thus, making their iron content (the main component of haemoglobin) readily available for red blood cell production (51, 53).

Adequate vitamin A during pregnancy is essential for maternal and infant health (54, 55). Dietary vitamin A is available from two main sources that is, plants (provitamin A) and animals (preformed vitamin A) (55). Animal foods rich in vitamin A include; eggs, organ meat and dairy products while dark green leafy vegetables, vitamin A rich fruits and vegetables are plant foods rich in vitamin A (36, 56, 57). In this survey, 35.5 and 12.6% of the respondents enrolled consumed plant and animal food groups rich in vitamin A, respectively. The observed low intake of vitamin A animal food groups among study respondents might be due to the inability of the women to purchase eggs, organ meat and milk products. Furthermore, intake of foods rich in vitamin A was associated with maternal haemoglobin levels. Similar correlations have been described elsewhere (18, 58–60). Inadequate vitamin A intake is thought to cause anaemia through; reduction of the body’s immune response to infectious diseases which in turn leads to anaemia of infection, modulation of erythropoiesis and iron metabolism (6, 58, 61). Besides, vitamin A deficiency is known to increase the risk of iron deficient erythropoiesis and subsequently anaemia by altering absorption, storage, release and transport of iron to the bone marrow (62). This phenomenon might explain the low Hb levels observed among those who did not consume foods rich in vitamin A.

The current study had some limitations. Firstly, its cross-sectional nature could not establish the cause-and-effect relationship between dietary components and anaemia. In addition, this study did not measure biomarkers of micronutrient deficiency and other indicators of anaemia such as; mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV), reticulocyte count. In contrast, this study has as strength in its sample size as well as minimised recall bias by employing the use of the 24-h recall method to assess dietary diversity. Moreover, this study further demonstrates the effect haem iron and vitamin A rich food groups has on haemoglobin levels. Besides, this study sets the basis for future works determining the association and comparative influence of iron and vitamin A on Hb levels.

Overall, the prevalence of anaemia (40.9%) was high despite adequate uptake of iron supplement (71.5%). Moreover, dietary diversity was inadequate (89.6%). In addition, anaemia prevalence rate was significantly (p < 0.05) lower in women who took IFA coupled with a diet rich in haem iron (38.5%) and vitamin A (29.0%). Furthermore, mean haemoglobin levels were significantly (< 0.001) higher in women who consumed haem iron (11.08 ± 1.35) and vitamin-A (11.34 ± 1.30) rich foods a day before the survey when compared with their respective contemporaries who did not. Thus, apart from focusing on iron-folic acid supplementation alone to curb the burden of maternal anaemia, public health authorities and health care givers should improve maternal nutritional awareness on the importance of a diversified diet as this would in turn enhance uptake of foods rich in haematopoietic nutrients thereby reducing anaemia prevalence rate.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.

The studies involving humans were approved by Institutional Review Board (IRB), Faculty of Health Science, University of Buea, Cameroon. The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin.

VJ: Formal analysis, Conceptualization, Data curation, Investigation, Writing – original draft, Writing – review & editing. JA: Formal analysis, Validation, Writing – review & editing. DS-F: Formal analysis, Validation, Writing – review & editing. GT: Formal analysis, Validation, Writing – review & editing. HK: Conceptualization, Supervision, Validation, Writing – review & editing. JA-K: Conceptualization, Supervision, Validation, Writing – review & editing.