How Drinking Garri Affect Eyes And Cause Blindness

There is a rumour in town that drinking garri can cause blindness. That is adding cool water to garri and eating it. And this is a common delicacy in Nigeria and other parts of the world.

Eyes

Because it is cheap and easy to prepare, it was the fast food for students. We enjoyed it with milk, groundnut and other additions.

Cassava or manioc (Manihot esculenta Crantz), is a perennial shrub of the New World. Like most tubers, cassava contains high levels of cyanide which together with sugar forms a compound (cyanogenic glycoside). This compound is toxic and serves to prevent herbivores from attacking tubers.

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Insufficiently processed products from cassava roots may contain residual amounts of cyanogenic glucosides, mainly linamarin, which is hydrolysed in the intestinal tract of both men and animals by microbial flora and hydrogen cyanide (HCN), a toxic metabolite is released which sometimes causes death.

How Eating Garri Cause Blindness

When properly processed, most of the cyanide is destroyed. The resulting garri contains very little amount of cyanide. However, poorly processed cassava will result in a high amount of cyanide. The World Health Organization safe level for cyanide in cassava flour is 10 ppm (10 parts per million or 10 mg per Kg).

Cyanide is slightly similar in structure to Cyanocobalamin (Vitamin 12). Vitamin B12 is a compound that supports nerves in the body including the optic nerve in the eyes.

So, cyanide competes with Vitamin B12 replacing it and affecting rapidly growing tissues or tissues that are regularly renewed such as the skin, peripheral nerves and the nerve of the eye – optic nerve. It’s the involvement of the optic nerve which leads to blindness.

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Cyanide toxins invades the thyroid gland and suppresses the production of thyroxine leading to goitre with its associated eye symptoms (thyroid ophthalmopathy). The cyanide in garri also suppresses the availability of natural vitamin A (which is paramount for retinal layer metabolism and a lot of optic nerve function) in the body.

Cyanide has also been implicated in destroying antioxidants that protect the eyes. All these are common in people who consume garri and are above 40 years of age.

Consumption of garri high in cyanide results in poorer visual acuity and color vision when compared with the non consumers of garri which was consumed over a long period of time. Consumption of processed cassava (gari) increases the high incidence of refractive errors among the consumers, which may consequently contribute to high prevalence of blindness and severe visual impairment.

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How To Avoid Blindness Cause By Eating Garri

A species of cassava known as wild cassava cultivars have greater cyanide content. Also, white garri contains higher amounts of cyanide than red garri. To reduce the effect, a diet high in vitamin B12 and protein will help. Also, avoid wild cassava cultivars and go for properly processed garri especially those with red colour as the oil will reduce the amount of cyanide. Adding hot water remove all traces of cyanide.