Emails are landing in my inbox lately with questions about cassava flour for gluten-free baking. These are not baking questions; they are concerns about cassava safety and about cyanide.
I thought it was time to write a Smart Nutrition Backed by Science article to share with you so that I can answer as many of those questions here. As more questions come up and as more research surfaces I will update accordingly.
Cassava Flour and Cyanide: Should I be Alarmed?
When questions like this started rolling into my inbox recently, it reminded me of the arsenic in rice scare a few years back. I received similar questions and many of you were emailing me telling me you threw out all your rice “to be on the safe side”. (I currently have rice in my own pantry, so before you toss yours out, read that post!)
Before you purge your pantry of all cassava products (cassava flour, cassava root, tapioca products, and any products containing those ingredients), take a look at the facts. Let’s begin… at the beginning.
What is Cassava?
Cassava is a tuber that is grown in Africa, South America and Asia. It is often referred to as manioc or yuca (not to be confused with the ornamental plant, yucca) and is sometimes called cassava root (the edible tuber grows underground). Tapioca flour (tapioca starch) is made from cassava and is a common ingredient in gluten-free baking.
You may have seen cassava root in the produce section of your supermarket. It is long, slender and dark brown with a thick, rough exterior. The inside is white. If you have ever purchased and prepared some, you know that the outer peel is very tough and the root itself is hard.
There are two primary types of cassava: sweet and bitter. The cassava that we see in the USA for consumption is the sweet variety. Bitter cassava requires extensive processing and is generally reserved for commercial processing.
Does Cassava Contain Cyanide?
Cassava does not contain cyanide per se, but it does contain a precursor to cyanide that can be acted on to create the toxic substance in certain circumstances, such as if the plant is attacked by a predator, insect, put in a stress situation such as adverse growing conditions, or during inadequate processing (this is more a concern with the bitter variety).
Cyanogens and Cassava
The precursor substances in cassava that induce cyanide production are called cyanogens. Approximately 90% of all cyanogens in plants are cyanogenic glycosides (also sometimes called cyanoglycosides).
A variety of plants contain cyanoglycosides. These compounds are nature’s way of protecting plants from insects and animals and stressful situations, as mentioned above.
The following are the top food crops that you and I are likely most familiar with that contain cyanoglycosides. According to the World Health Organization (WHO; see page 4 of document), there are at least 2000 plants that contain naturally occurring cyanoglycosides.
I have listed the botanical name, italicized in parentheses beside each plant and have also indicated the part of the plant that contains the cyanoglycosides.
Food Plants Containing Cyanoglycosides
- Cassava root and leaves (Manihot esculenta)
- Flax seed (Linum usitatissimum)
- Sorghum leaves (Sorghum vulgare)
- Lima beans (Phaseolus lunatus)
- Apple seeds (Malus spp.)
- Almonds (Prunus dulcis)
- Bamboo shoots (Bambusa arundinacea)
- Peach kernels (pits) (Prunus persica)
- Apricot kernels (Prunus armeniace)
- Nectarine kernels (Prunus persica var nucipersica)
- Plum kernels (Prunus spp.)
- Cherry pits (Prunus spp.)
There are different types of cyanoglycosides. In the cassava plant, the primary cyanoglycoside is linamarin.
Cassava roots contain much less cyanide-inducing compound than the leaves.
According to research, the linamarin content in the leaves of the cassava plant is far greater than that in the roots. In fact, it is estimated that cassava roots contain less than 10% of the amount of linamarin than that found in the leaves. This is good news since the roots are used to make cassava flour, tapioca flour and other products you and I are likely to consume.
Sweet cassava contains only small amounts of cyanoglycosides in the starchy root.
Even better news is that research shows sweet cassava, the variety most of us are familiar with, contains very low levels of cyanide-inducing compounds in the starchy flesh. Most of the toxic compounds are contained in the outer peel, which is stripped away and discarded before processing.
How much cyanide-inducing compound is in cassava?
The exact amount of cyanoglycosides in a plant varies and depends upon factors such as plant genetics, environmental conditions, soil, water, location and season in which the plant grows. According to the WHO (see page 12 of document), these compounds in cassava tubers vary widely, but tend to fall in the range of between 15 and 400 mg/kg fresh weight.
Processing of cassava alters cyanide levels.
According to various researchers who study cassava and its cyanide content, a significant amount of the toxins in the plant are released as gas into the air during processing. In fact, the greatest risk of harm from cyanide from cassava (especially the bitter variety used frequently outside the USA) is to workers who process the roots, not to consumers eating a finished cassava products. (This in itself is an extremely important and disturbing issue reminding us of the impact our food choices can have on others, but not one to address in this post.)
So, should you avoid all the foods on the list above and be paranoid about cyanide poisoning because you’ve been using tapioca starch and cassava flour in your gluten-free baked goods?
Based on the research and facts from science, no. If you eat a balanced diet and are not eating only those foods or excessive amounts of those foods, there should be nothing to worry about.
My 2-cents’ worth on extremism with any product and a word about nutritional content.
This seems a good time to mention any food in excess is not a good thing when it comes to our health.
When certain products or diets hit the market and a “craze” follows, people can go overboard.
It reminds me of my friend K. She is a fantastic cook and always used a wide range of products and ingredients in her dishes. A couple years ago, I was surprised when I visited her one day to learn she had thrown out all of her cooking and finishing oils because, in her words, “coconut oil is the only healthy oil”.
I was astounded. How could this educated woman who knew so much about food fall victim to media hype for a single product? I see it every day, though, in social media and via emails and comments I receive as a result of my work in special diets nutrition.
I’m not singling out coconut oil – it is just an example of how I see folks with the best intentions for their health and overall wellness go overboard with a single product and use only that product, often in excess.
Of course, I have coconut oil on the shelf (and I’ve written about it here), but I also have about a dozen other oils alongside it. I use them all because no single oil is right for every application.
The same goes with gluten-free flours and starches. As someone with celiac disease, I am grateful to have a multitude of gluten-free baking ingredients available to me. As a recipe developer, those base ingredients are the “tools of my trade”. BUT, it does concern me a bit when I see people over-using some products (like my friend and her coconut oil).
If you read here often, you know I am about balance and moderation. A diet that includes in-season fruits and vegetables and a wide variety of foods (that agree with our individual special dietary needs, of course) is the best way to ensure we are getting the nutrients our bodies need.
And what about all the sweet treats you find here on my site? Remember, I am a recipe developer. That, along with being a science writer, author and magazine editor is my full time job, so all those dessert recipes I post are certainly not what I eat every day. Of course, if you want a sweet treat, I believe you should enjoy one, totally guilt-free. Balance.
Cassava Flour Nutrition
These days, cassava flour is all the rage in grain-free and Paleo baking. I use it on occasion, I like it and I think it’s a great product for those who want to use it.
I do not label myself as anything in terms of the food I eat besides gluten-free (due to celiac disease) and soy-free and nut-free (due to food allergies to these foods).
Beyond the “have to” labels, I find labels bothersome and unnecessary for me. I choose healthy foods, eat in-season, and when I want a treat, I have it unapologetically (and label-free!). But I do respect others who choose to label the way they eat. It’s just that…
Sometimes I wonder if suddenly popular products are understood fully in terms of nutrition.
I understand cassava is not a grain (technically, from a botanical perspective, neither is rice – it is the seed of a grass plant), so it is highly appealing to those who live a grain-free lifestyle, but most of the people following the paleo (or similar) way also seem to aim for a lower refined carbohydrate diet, as well. At least that is what I gather from reading about the paleo/grain-free way of eating. (Feel free to comment below if you have thoughts or clarification on this.)
For the sake of comparison, here are the basic nutritional facts for 100 grams of cassava flour and a few other products – brown rice flour, chickpea flour and arrowroot.
If you’re counting carbohydrates, you may want to note cassava flour is not a low carb product, even considering the fiber whole cassava flour contains (versus tapioca starch).
If you’re after a few less carbs and more fiber and a protein boost, you may want to consider chickpea flour (although I am not a fan of the brands in the USA, the brands here in France are very mild with no bean odor or flavor).
Again, this is just a comparison (and certainly not an “apples to apples” comparison; it is not intended to be). This is to get you thinking about overall nutrition and the products we use in our gluten-free diet. There are many, many others we could list and compare. I simply chose these to provide a wide variety.
Nutritional Content of 4 Gluten-Free Flours for Comparison
Cassava Flour (nutrition information from Otto’s Naturals Cassava Flour website (this is NOT an affiliate link)
Total fat: 0.5 g
Total carbohydrate: 93 g
Dietary fiber: 7 g
Sugars: 1 g
Sodium: 0 mg
Cassava flour contains 90mg calcium, 4 mg vitamin C, and 1 mg iron.
Brown Rice Flour (nutrition information from Bob’s Red Mill website – you will need to do a bit of math to get the 100g amount)
Total fat: 2.5 g
Total carbohydrate: 77.5 g
Dietary fiber: 5 g
Sugars: 0 g
Protein: 7.5 g
Sodium: 12.5 mg
Brown rice flour contains a significant amount of daily iron intake for adults, approximately 10% of the recommended daily allowance.
Chickpea Flour (also called Garbanzo Bean Flour; nutrition information from Bob’s Red Mill website – you will need to do a bit of math to get the 100g amount)
Total fat: 7 g
Total carbohydrate: 60 g
Dietary fiber: 17 g
Sugars: 10 g
Protein: 20 g
Sodium: 17 mg
Chickpea flour also contains a significant amount of daily iron and calcium.
Arrowroot (nutrition information from Bob’s Red Mill website – you will need to do a bit of math to get the 100g amount)
Total fat: 0 g
Total carbohydrate: 88 g
Dietary fiber: 3 g
Sugars: 0 g
Protein: 0 g
Sodium: 0 mg
Keep in mind, I am not telling you whether or not to eat any specific foods. I am providing you with the science-based facts so that you can make the best decision for your unique situation and dietary needs.
In addition to the research about cassava and cyanide linked in the article above, you can find more information on this topic in these places:
- You can read basic facts about cyanide from the Centers for Disease Control here.
- The Hong Kong Food Safety Center has published fact-based research on cassava here.
- Read about anti-nutritional factors in foods like cassava from the Food and Agriculture Organization of the United Nations.
Disclosure and Transparency
This post is not a sponsored post by any brand or company. It is strictly fact-based, written by me for you, my readers, to assist you in making the best decisions for your gluten-free lives as a result of an abundance of questions recently received via email from many of you.
In the interest of transparency and full disclosure, I do want you to be aware of the following:
- I share recipes using Otto’s Cassava Flour here on this site.
- If you purchase Otto’s Cassava Flour from this site via the links I provide in any recipe post, or via the image in the right side bar, I receive a small amount of compensation (although this doesn’t alter the price you pay at all). It’s just a way to help me keep the bills paid so that you can enjoy the website free of charge.
This article is to share unbiased scientific information to help you make the best decision for your gluten-free diet.