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Does Cassava Flakes Affect the Eyes?

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Health Writer | Health content creator | Medical Researcher
Bags of garri

You probably must have heard people say that cassava flakes affect the eyes. As with every myth or belief, it is important to examine the scientific truth behind it and separate fact from fiction.


  • Cassava flakes (Garri) is one of the most consumed foods in Nigeria.
  • People erroneously believe that cassava flakes affect the eyes because of the cyanide in unprocessed cassava tubers. 
  • When the cassava doesn’t receive enough heat during processing, the cyanide affects the optic nerve when consumed. 
  • The cyanide in garri (that isn’t adequately processed) can suppress the body’s natural vitamin A (which is essential for the optic nerve to function). 
  • No scientific evidence supports the claim that cassava flakes affect the eyes.
  • Moderation and a diverse diet promote eye health.
  • Seek professional advice from eye care specialists on KompleteCare for any eye health concerns.
  • Regular eye check-ups and proper eye care practices are crucial for maintaining good vision.

The notion that cassava flakes (garri: a popular West African food made from cassava) can cause eye problems is common in nearly every part of Nigeria and perhaps West Africa. This belief has been passed down through generations and is a big part of the culture. Most people, especially those in rural areas, adhere firmly to this belief and may limit their consumption of cassava flakes.

The belief is so popular that when people (especially students) drink it excessively, they go the extra mile of taking eye drops afterward (like in some comedy skits) or mixing it with milk and groundnut to douse the effects on their eyes.

However, this mentality lacks adequate scientific evidence or research that links eye problems to garri consumption. As with every myth or belief, it is important to examine the scientific truth behind it and separate fact from fiction.

This article sheds more light on this popular belief by providing a clear understanding of the relationship between drinking garri and eye problems by examining available research. Through evidence-based information, this article explores whether there is any merit to the claim that cassava flakes affects the eyes and contributes to a more informed perspective.

What is Cassava flakes (Garri)? 

Does Cassava Flakes Affect the Eyes?
Does Cassava Flakes Affect the Eyes? 4

Garri (gah-ree) is the end product of the arduous and lengthy process of processed and granulated cassava (a root vegetable) that is poisonous unless peeled and cooked. Cassava is poisonous because it contains toxic levels of cyanide and can cause systemic cyanotoxicity when consumed raw or not well-processed. 

Cassava flakes, also called Garri (in local parlance), is produced from two types of cassava tubers: sweet cassava and bitter cassava. Sweet cassava can be consumed safely when peeled and thoroughly cooked because it only has 50mg per kilogram of cyanide. However, the bitter cassava tuber is only safe for consumption when processed more thoroughly because it contains approximately 400mg per kilogram of cyanide.

Cassava flakes (Garri) is commonly found in West Africa and comes in two types: Yellow garri and white garri. The color and taste are influenced by fermentation duration and palm oil’s inclusion when frying. Yellow garri is fried with palm oil and is less fermented, which is why it has a sweet taste. White garri, on the other hand, is plain and fermented for a more extended period which is why it acquires a sour taste (Ijebu garri). 

Nevertheless, for Nigerians, garri is more than just a cassava product. It is a go-to food when times are tough, when you’re tired, when there’s no food, or when you don’t have the time to settle down to cook. Garri is considered a hero by most Nigerians, especially students, because of its convenience. 

It is also seen as a magical food because of its ability to increase in volume when mixed with water. This has led to a rapid increase in demand for this convenient food, making it a fast-rising marketable product in Nigeria.

This life-saver is a beloved and chief commodity food in Nigeria and is deeply ingrained in Nigeria’s culinary culture. Garri is a popular choice among Nigerians of all ages, ethnicity, and social backgrounds, making it one of the most consumed foods in the country. Whether in cities or rural villages, garri is a necessary commodity in the kitchen, is consumed in various forms, and is significant in Nigerian diets.

Garri: Production Process

Garri is made from crushed cassava roots/tubers, a starchy root vegetable that grows in Nigeria. The production process involves peeling, washing and grating, dewatering, fermenting, and sieving the cassava roots to extract the starchy pulp. 

  • Peeling: Freshly harvested cassava tubers are covered with soil and dirt, so the outer brown skin and inner thick cream layer are peeled off the roots. Small and medium-scale garri producers commonly use this method. However, it is very time-consuming, so large-scale producers prefer to use machines instead.
  • Washing: The peeled cassava roots are washed in clean water to remove stains and dirt.
  • Grating: The cassava roots (that are not rotten) are grated into a mash which is part of the process of removing cyanide, making them safe to consume. 
  • Dewatering and Fermentation:  This completely eradicates the cyanide from the cassava. The fermented cassava mash or pulp is kept in a sack bag, and a hydraulic press or logs are used as heavy weights to press and drain the excess water out of the mash. The bags are left to drain freely for a day or two. 

This pulp is then fermented for a few days to enhance its flavor and reduce the cyanide content. Once fermented, the pulp is sieved, pressed, and roasted to produce the final product – garri.

The importance of garri in Nigerian diets is not just because of its availability and affordability but also its versatility. Garri is a reliable source of carbohydrates, providing sustenance and instant energy. 

Garri is often used as a base for various dishes and complements many Nigerian soups and stews. It has a long shelf life, making it a practical and preferred choice for storing and consumption in places where food preservation is needed.

Various Ways Cassava Flakes (Garri) is Consumed

Thanks to the culinary creativity of Nigerians, garri can be enjoyed in several ways.  

  1. Eba and soup

One of the most common and traditional consumption methods is soaking it in hot water to produce a dough-like texture known as “Eba” or “garri fufu.” Eba is a classic Nigerian swallow dish paired with various soups like Egusi soup, Vegetable soup, Ogbono soup, Okro soup, Oha soup, etc, creating a delicious and satisfying meal.

  1. Garri Soakings

Garri can also be enjoyed as a cereal by mixing it with (cold) water and groundnut (peanut), or cashew nuts, milk, and sugar. Garri soaking is one of the popular ways garri is consumed in West Africa. Soaked garri is an excellent option for lunch, especially when you want something light and sustainable. 

  1. Garri cake

Garri cake is a popular recipe that originated from boarding schools. This boarding school delight is made exactly like cake. The only difference is that the flour is replaced with garri. 

  1. Garri Biscuit

This is baked dough of garri and other baking items. It can be eaten straight out of the oven or paired with soup. The primary ingredients for this recipe are garri (mostly), sugar, groundnuts, (almond) milk, and hot water.

Does Cassava Flakes Affect the Eyes?

This is a question that has lingered for decades. Fortunately, garri does not cause eye problems. People believe that it does because of the cyanide in unprocessed cassava tubers.

When the cassava doesn’t receive enough heat during processing, the cyanide affects the optic nerve when consumed. The cyanide in garri (that isn’t adequately processed) can suppress the body’s natural vitamin A (which is essential for the optic nerve to function). 

No scientific evidence supports the claim that cassava flakes affect the eyes. However, it’s essential to know why most people believe in this claim and the potential factors that might have contributed to the spread of this myth.

Is Garri Bad for the Eyes?

The belief that garri causes eye problems may have originated from cultural beliefs, traditional knowledge, or anecdotal experiences within specific communities. Folklore and superstitions often play a significant role in shaping people’s beliefs about food and health.

In some cases, individuals might have experienced eye problems coincidentally after consuming garri or know others with eye problems who also consumed garri. Such circumstances could lead to a perceived association between garri consumption and eye problems, even though there is no direct link.

Why Do People Believe that Cassava Flakes Affect the Eyes?

Does Garri Cause Eye Problems?
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The spread of the myth (about garri causing eye problems) could be influenced by various factors, which include:

  • Word of mouth: Through word of mouth, misconceptions, rumors, superstitions, and beliefs can spread quickly within communities, especially when there is no scientific evidence (or information) to counter such claims.
  • Cultural practices: Some regions believe that certain foods have specific health effects, and these beliefs are passed down from one generation to the next.
  • Lack of awareness: When people don’t know any better, they are liable to swallow any claim or belief that comes their way. Limited access to accurate information on health education can perpetuate myths and misconceptions surrounding garri and its impact on eye health.
  • Misinterpretation of symptoms: There are various causes of Eye problems, including genetic factors, age-related conditions, or underlying health issues. It is possible that people link eye problems to garri consumption without considering other potential factors.

Nutritional Composition of Garri

The nutritional composition of Garri varies depending on the type of cassava that was used, processing methods, and additional ingredients (like cocoyam) used to prepare it. According to a study, the cultivation methods, management practices, and type and length of fermentation contribute to the nutritional composition of garri.

Cassava is the main ingredient in garri; therefore, garri primarily contains carbohydrates with few proteins and fats. 

  • Carbohydrates: Garri is rich in carbohydrates, particularly resistant starch (similar to insoluble fiber), providing energy to the body.
  • Proteins: The amount of protein in garri is relatively low (since it is majorly carbohydrates) compared to other protein-rich foods. Nevertheless, it has some protein to give.
  • Fats: Garri has small amounts of saturated and unsaturated fats.
  • Vitamins: Garri may contain various vitamins like B vitamins (e.g., thiamine, riboflavin), vitamin C, and folate, depending on the type of cassava and processing methods.
  • Minerals: Such as calcium, magnesium, potassium, and phosphorus.

Additionally, garri is rich in copper, fiber (which aids digestion and prevents constipation), vitamin B6, and niacin. Yellow garri contains more vitamin E because it is prepared with palm oil. 

Regarding eye health, garri has a healthy dose of vitamin A (which the retina in the eyes needs to function well). Vitamin A is known for maintaining good vision and optimal eye health and preventing myopia (shortsightedness) in children and young teenagers. 

The Link Between Vitamin A Deficiency and Eye Health

Vitamin A is crucial for healthy vision and proper functioning of the retina, the light-sensitive tissue at the back of the eye responsible for transmitting visual information to the brain. It is necessary for optimal night vision, as it helps the eyes adapt to low-light conditions. 

The eyes need to produce certain pigments for the retinas to function correctly. Lack of vitamin A prevents the eye from manufacturing these pigments, leading to night blindness. In other words, you need vitamin A to see at night.

Vitamin A Deficiency and Its Impact on Eye Health

Vitamin A deficiency is a global health concern, particularly in developing countries like Nigeria. According to a study, Vitamin A deficiency (VAD) is the primary cause of blindness in children and a significant factor contributing to severe infections and mortality in children from developing countries. 

According to the study, Approximately 130 million preschool children are estimated to have subclinical Vitamin A deficiency, characterized by a serum retinol concentration of less than 20 μg/dl or 0.7 μmol/l. 

Insufficient Vitamin A leads to a condition known as “night blindness,” where individuals find it difficult to see in dim light or at night. In more severe cases, Vitamin A deficiency can cause a condition called xerophthalmia, which can permanently damage the cornea and eventually lead to blindness.

Other Sources of Vitamin A in the Nigerian Diet

While garri contains a significant amount of Vitamin A, other foods in the Nigerian diet provide this essential nutrient. Other sources of Vitamin A in the Nigerian diet include:

  • Orange and yellow fruits and vegetables: Fruits (like mangoes and papayas) and vegetables like carrots, sweet potatoes, and pumpkins are rich in beta-carotene.
  • Dark leafy greens (Efo Riro): Vegetables such as spinach, kale, and ugu (pumpkin leaf) are good sources of Vitamin A.
  • Tomato Stew
  • Liver: Organ meats, particularly liver, are rich in retinol, the active form of Vitamin A.
  • Eggs: Egg yolks contain a small (but sizable) amount of Vitamin A.
  • Moi Moi
  • Sweet Potato Porridge
  • Carrot Stew/ Pawpaw
  • Pepper Sauce: Red pepper has more vitamin A than green pepper.

Including these Vitamin A-rich foods in your diet can help prevent Vitamin A deficiency-related eye problems. However, if you are at risk of Vitamin A deficiency or have concerns about your eye health, consult a healthcare professional for adequate guidance and supplementation if necessary.

Does Garri Cause Eye Problems?

Scientific studies examining the relationship between Garri consumption and eye problems are limited. 

According to a 2021 study, consuming partially-processed cassava for a long time can lead to systemic cyan toxicity, which has detrimental effects like neuropathy, thyroid dysfunction, and poor vision. 

However, the study concluded that with improved and proper processing techniques, the cyanide level in cassava reduces, eliminating cyan toxicity and poor vision. This establishes the fact that adequately processed garri does not cause eye problems.

However, another study revealed that those who consumed garri had poorer color vision and visual acuity than those who didn’t consume it. This study examined only 108 subjects for the degree of visual defect after consuming garri for a very long time. Therefore, this study is limited as the sample size is too small to account for the entire or majority of the Nigerian population.

As discussed earlier, Vitamin A deficiency can lead to eye problems. Garri has a significant source of Vitamin A; therefore, VAD and eye problems often arise due to a lack of diversity in one’s diet.

There is limited research on the link between Garri consumption to eye problems. This highlights the need for more comprehensive studies to investigate any potential associations. Additionally, other factors may contribute to Vitamin A deficiency and eye problems in certain regions where Garri is prevalent.

What Causes Eye Problems in Nigeria

Several factors contribute to the prevalence of eye problems in Nigeria. According to a study, the primary cause of blindness and visual impairment in West Africa is uncorrected refractive error, cataract, glaucoma, and corneal disease. 

Another study also concluded that uncorrected refractive errors were the prevalent cause of mild visual impairment, while cataract was the major cause of severe visual impairment and blindness in Nigeria. The study also found that 84% of blindness in Nigeria could have been prevented.

Other potential causes of eye problems in Nigeria include:

  • Environmental factors
  • Infections: Eye infections, like conjunctivitis, is another factor and are caused by bacteria, viruses, or other pathogens.
  • Aging: Conditions like cataracts and age-related macular degeneration become more prevalent as people age.
  • Uncontrolled diabetes: Diabetes can affect the blood vessels in the eyes, leading to diabetic retinopathy and loss of vision if left untreated.
  • Glaucoma.

Lifestyle factors and eye care practices that maintain eye health include:

  • Phone and screen usage: Staring at screens for long periods can cause digital eye strain and make your eyes dry. To reduce the strain on the eyes, practice the 20-20-20 rule: take a 20-second break every 20 minutes and look at something 20 feet away.
  • Proper eye protection: Make it a habit to wear sunglasses outdoors. It will shield your eyes from harmful UV rays and reduce the risk of developing cataracts.
  • Smoking: Smoking increases the risk of eye diseases like cataracts and macular degeneration.

Eye problems caused by nutritional deficiencies are often due to the lack of essential nutrients, vitamins, or minerals necessary for eye health, like vitamin A deficiency leading to night blindness. Some common eye problems caused by nutritional deficiencies include night blindness, dry eyes or inability to produce tears, dying corneas, and reduced visual acuity.

On the other hand, eye issues caused by other factors, such as cataracts and glaucoma, are not associated with nutritional deficiencies but may result from various genetic, environmental, or lifestyle factors.

Healthy Consumption of Garri and Eye Health

Garri is very rich in carbohydrates, providing energy for your day-to-day activities. Garri is also rich in Vitamin C and some B-complex vitamins that maintain general health. Additionally, garri contains small amounts of minerals like calcium, magnesium, and potassium.

However, consume garri in moderation and along with other nutritious foods. You can include fruits, vegetables, whole grains, lean proteins, and healthy fats in your diet to maintain and promote eye health.

As you strive to create a balanced diet, visit the doctor for regular eye check-ups to detect eye problems early on and manage them. Other little (but important) ways to maintain eye health include adequate rest, proper hygiene, and wearing protective eyewear when necessary. 


Garri will forever hold a special place in the hearts and palates of Nigerians because of its distinctive taste and versatility. It is a symbol of Nigeria’s rich culinary culture, and the love for garri has endured through many years. 

Although Garri may be a popular and highly nutritious food in Nigeria, there is no direct relationship between its consumption and eye health issues. More scientific evidence is needed to support this claim.

This doesn’t mean you should stop consuming garri altogether (don’t let this article scare you). As long as your Garri is adequately processed, you are safe to enjoy it with a big smile. 

However, as with any dietary choice, moderation and a well-balanced diet contribute to overall eye health. Do not depend solely on garri (although it is nutritious) in your diet.

If you have any (specific) eye health concerns, seeking professional advice from an eye care specialist on KompleteCare is highly recommended. Stay informed, and stay healthy!


Yusuf, A. & Zakir, A & Shemau, Z & Abdullahi, Mubarak & Halima, Slaoui & Sani, Khosy. (2014). Visual defects among consumers of processed cassava (gari). African Journal of Food Science. 8. 25-29. 10.5897/AJFS2013.1093.

O. Akinbami, C. A., & Momodu, A. S. (2013). Health and Environmental Implications of Rural Female Entrepreneurship Practices in Osun State Nigeria. Ambio, 42(5), 644-657.

Maduelosi, Ngozi & Onuigbo, U. & Egede, B.. (2023). EFFECT OF DAYS OF FERMENTATION AND PALM OIL ON THE LEVELS OF CYANIDE IN GARRI SAMPLES. Journal of Chemical Society of Nigeria. 48. 10.46602/jcsn.v48i1.848.

Fajemisin, Emmanuel & Ogungbemi, Segun & Aborode, Abdullahi. (2021). Partially-Processed Cassava Tubers on Poor Eye Vision in Nigeria: Impacts and Solutions. SSRN Electronic Journal. 10.2139/ssrn.3833117.

Bamidele, O. P., Ogundele, F. G., Ojubanire, B. A., Fasogbon, M. B., & Bello, O. W. (2014). Nutritional composition of “gari” analog produced from cassava (Manihot esculenta) and cocoyam (Colocasia esculenta) tuber. Food Science & Nutrition, 2(6), 706-711.

Nwokoro, Smart & D, Adegunloye & Fidelis, Ikhinmwin. (2005). Nutritional Composition of Garri Sievates Collected from Some Locations in Southern Nigeria. Pakistan Journal of Nutrition. 4. 10.3923/pjn.2005.257.261.

Ukponmwan, C. U. (2013). Pattern of ocular morbidity in Nigeria. Asian Pacific Journal of Tropical Disease, 3(2), 164-166.

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Claire Essi

Claire Essi is a health researcher and freelance health content creator. As a health and wellness junkie, she enjoys all things related to quality lifestyle and healthy living.

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