Eating Chalk (Nzu) During Pregnancy Affects Children's Learning


Here at we often get questions from some readers who are addicted to eating clay or chalk.

Local chalk is not a conventional food though consumed by a wide range of communities. In Nigeria, pregnant and breast feeding women patronize it the most.

This chalk which is natural and made up of fossilized seashells may be prepared artificially from clay and mud. This combination may then be mixed with other ingredients including sand, wood ash and sometimes salt. The resulting product is molded and then heated to produce the final product.

Different names have been ascribed to this chalk depending on which part of the world it is found. It is known as La Craie or Argile in French, Nzu and Ndom by the Igbo and Efiks/Ibibios respectively of Nigeria, and Mabele by the Lingala of Congo. It is sold in blocks, pellets and powder forms.

While not many people know this, local chalk is composed of Aluminum silicate hydroxide from the kaolin clay group with the possible formula: Al2 Si2 O5 OH4. This has been tested to contain lead and arsenic.

Exposure to lead can result in a number of harmful effects, and a developing child is particularly at risk of effects on the brain and nervous system. Arsenic is a carcinogen, and excessive long-term exposure to it has been associated with a range of adverse health effects, including cancers of the urinary bladder, lung and skin.

Furthermore, a new study on Kenyan pregnant women's eating habits shows that consumption of non-food items impacts on their children’s learning ability.

The study shows a correlation between once bright children who later become underachievers in school, “yet they possess such great abilities and talents” and factors related to birth or pregnancy.

Titled, Impact of “pica” (non-foods) practice among pregnant mothers on cognitive intelligence [learning ability] of the child, the study cautions against eating items that have no food value, which can later affect the full development and growth of the child.

The research which is the first ever to be conducted in Kenya to ascertain effects of ‘pica’, (the practice by mothers to consume non-food items during pregnancy, such as soil, matches and chalk), shows up to 77.9 per cent of pregnant women in the country engage in the habit.

The President of the African Council for Gifted and Talented, Humphrey Oborah called for enhanced education and sensitization to parents and teachers on the adverse effects of pica on overall health and growth.

“Parents, particularly pregnant mothers need to be educated strongly on the impact of pica on their own health, the born baby but even more importantly on the final future learning challenges to the child.”

Oborah said that the study on pica was commissioned,

“After it emerged that most young people that were referred for assessment on Gift and Talent Testing showed a significant trend of relationship in factors related to birth or pregnancy and those related to learning abilities”.

“Whereas previous documented research on pica concerned health related problems with the mother in focus, nothing has been known or done on the impact of pica on the learning ability of the born child.”

A total 476 female and 468 male children were included in the study, which was conducted in Kenya’s major cities, with 1324 mothers saying they have consumed non-food items during pregnancy.

Mothers aged 16-20 years recorded the highest prevalence of pica practice at 26.6 per cent, followed by 21-25 and those below 15 years age bracket at 17 and 13.5 per cent respectively.

“Majority of children [42.1 per cent] whose mother practised pica had weak cognitive ability, 32.3 per cent had medium ability and 3.4 per cent had high ability,” the report said.

For women who are addicted to eating Nzu, this website offers useful tips on how to quit.