Several debates have been stirred concerning the potency of the Calabash chalk, popularly called ‘Nzu’ in Nigeria. While some are beholden to its acclaimed cultural benefits and significance, modern medicine validates through several experiments that it is harmful to the body.
Despite warnings, the geophagic substance is still consumed for mere delight especially by a fraction of pregnant women who believe it prevents vomiting, over-salivation and nausea.
Nzu is a natural composition of fossilized seashells that forms in places like mining pits or made artificially by mixing clay, sand, wood ash and salt. The finished look is either coloured white or ash, in powder form or moulded in a round shape or block.
Nigeria has the largest users of Nzu, especially within the Igbo tribe. In the past, it was used for certain traditional practices. To signify that a guest is welcomed in a home, he is given the white chalk to touch and rub on his wrist to depict a sign of ‘good heart’ from the host.
The Igbos also believe Nzu denotes wisdom. It was used to draw lines called ‘Oguama’ on the floor to signify “Purity and Holiness”. A man can only prove his holiness by observing Oguama. Also, whenever the elders met, each draws eight lines with the white chalk to signify sinlessness.
As time passed, people found other uses for Nzu besides traditional rites and began to eat them. A lot of people who consume Nzu often blame it on addiction because asides for the pleasure of it, they actually don’t know why they do. Scientists call the addiction ‘geophagy’. It is a craving to chew soil-like substrates like clay or chalk. The practice is prevalent among tribally oriented people.
Experts believe that the habit of eating the white chalk started in olden-day Africa. The locals made up for their lack of nutrients by consuming clay and dirt before it metamorphosed into various uses like prevention of morning sickness during pregnancy, detoxification, and pica syndrome.
However, there are safety concerns as regards the consumption of Nzu. In 2005, a group of scientists in Malaysia took 24 pregnant Wistar rats into the laboratory. Divided equally, a group was orally administered about 800 mg/kg of Nzu from gestation day 0 to 22. The aftermath of the experiment was that the foetus of the Wistar rats who had been administered Nzu, had an increased body weight and fatal changes in the cerebral cortex of foetuses.
The main property of Nzu is lead. Lead ideally should not be more than 1 mg/kg in a meal but a ball of Nzu contains 10–50 mg/kg. Imagine what happens to the organs of an individual who consumes about three to five blocks daily due to addiction?
Overuse of the substance results in the deterioration of the digestive system, unhealthy blood circulation, deformation of bones, nausea, ulcers and gastritis.
Still wondering if Nzu is bad for you? Yes it is. Except for cultural reasons, geophagy is attributed as the main cause of its mass consumption. If you get the urge to consume Nzu often, visit your doctor to provide you with a better nutritional option.