Is it safe to eat buckwheat every day

Rather than make you read through the entire post to get to the answer I will give the short answer here: buckwheat is safe to eat buckwheat every day. 

I had a few people ask me about the possibility of issues from eating buckwheat every day, most of these questions have been surrounding a compound called fagopyrin.  I am not an expert, and I am not a food scientist, so I did a bit of research, and decided to write what I found in a blog post so I can find it again.  

Too much fagopyrin over a long time period can cause phototoxicity, which is a sensitivity to sunlight and causes skin issues.  I was not sure how much is too much.  Many plant based foods have some level of toxins or anti nutrient.  I am not a food scientist ad didn't have more than a basic level understanding of the topic, so I did some reading into how safe buckwheat really is.  The results were interesting but not overly surprising.  

Common buckwheat with heart shaped leaves

Buckwheat seed has been eaten by people since at least the year 6,000 BC.  There have been few reliable reports of people having issues due to consuming buckwheat.  Based on this information alone, buckwheat seed appears to be safe to eat.  The actual answer, however, is more complex than a simple yes or no.  

Buckwheat seeds, sprouts, leaves, stems, rhizomes, and flowers have all been important sources of food or medicine for thousands of years, over the past few hundred years it has also been used as animal forage or silage.  

Consuming buckwheat has been demonstrated to help prevent various chronic illnesses, such as hypertension, obesity, cardiovascular disease, tumors, and gallstone formation.  Various pharmacological studies have confirmed that buckwheat holds anti-diabetic, anti-tumour, anti-inflammatory, antioxidant, and hepatoprotective effects.  All of this is great, but still doesn't answer if it is safe to eat buckwheat every day, or how much is too much.  

There are some reports of animals experiencing phototoxicity due to buckwheat's fagopyrin content.  These animals ate nothing but buckwheat stems, leaves, and flowers for weeks on end, which means that this only proves that like everything else too much is not great.  To put this perspective, if I ate nothing but apples for weeks on end I would become dreadfully unwell.  The question still remains, how much buckwheat is too much?  

Anecdotally I can say from experience that eating buckwheat groats every day is safe.  I have been eating grechnevaya kasha every day for breakfast for around two years, during that time I have become healthier in measurable ways (lower cholesterol, better LDL:HDL ratio, more stable blood sugars etc).  Buckwheat is highly nutritious, it is simple to prepare, and I like the taste.  

Anecdotal evidence based on personal experience is fine, but it doesn't answer the question over how much is too much, and actual evidence is always far better than anecdotal evidence.

Raw buckwheat groats

There have been rare reports of people reacting poorly to buckwheat seed, many of these have been food allergies.  The reports of skin sensitivity issues are almost entirely from people consuming large quantities of sprouts (and sometimes flowers) over an extended period of time.  So far I have found no reliable reports of anyone experiencing fagopyrism from eating hulled buckwheat seeds.  

When looking at the massive number of people who eat buckwheat seed as a staple food (hundreds of millions of people), and the extended period of time this has occurred (thousands of years), and the relatively few instances of problems, buckwheat appears to be safer to consume than wheat, milk, or eggs.  From this we can conclude that eating buckwheat is safe, but this still doesn't answer the question of how safe is buckwheat, or how much is too much.  So I did some more reading and crunched some numbers to actually answer these questions.  

Reliable data in peer reviewed papers on the fagopyrin content of buckwheat seed is scarce, and there is almost no information on the phototoxic dose in humans.  

The literature states that in leucistic/albino rats, slight skin issues start to be seen when feeding around 2.5 to 3 mg fagopyrin per kg body weight (with severe issues starting between 5 to 10 grams per kg body weight).  While humans are not rats, and most people have more melanin than these leucistic rats, this is the best analogue we currently have. 

The lowest end of this range, feeding 2.5mg/kg body weight extrapolates to 150mg of fagopyrin as being safe for a 60kg person.  I realise that extrapolation does not always work in a perfectly linear way, and this is based on the amount that causes issues in leucistic/albino rats rather than people, but it is the best we can do considering the surprising lack of human research.  I also realise that most people weigh considerably more than 60kg, so this acts as a bit of a buffer.  

Buckwheat leaf on right, fishmint on left

Fagopyrin is present in different amount at different stages of growth, and different concentrations are found in stem, leaf, flower, seed, and hulls of buckwheat.  While there are discrepancies in the literature about the amount of fagopyrin detected, there is general consensus that buckwheat seed contains the lowest concentration of fagopyrin.  

Several papers have reported detecting up to 0.07mg per gram in raw Tartary buckwheat groats.  Tartary buckwheat is Fagopyrum tataricum they did not specified if they were dehulled or included hull.  I am yet to find any mention of detectable amounts of fagopyrin in common buckwheat (Fagopyrum esculentum) groats.  While I assume these higher results may have included the hull, thus increasing the fagopyrin content and decreasing protein content, I am going to use the highest number in my calculations.  

While I am yet to find any paper where dehulled common buckwheat (Fagopyrum esculentum) groats had any detectable level of fagopyrin, and while I am not able to buy anything other than dehulled common buckwheat, to err on the side of safety I am going to use the highest levels detected from Tartary buckwheat in my crude calculations.  

If we use the lower safe amount of 2.5mg fagopyrin per kg bodyweight, and take the higher amount of 0.07mg/g fagopyrin possibly being contained in the seed, this would mean that a 60kg person would not run into issues with fagopyrin unless they eat over 2.1kg of raw buckwheat groats to reach the 150mg safe thresh hold.  

Given that it is likely that the amount of fagopyrin is lower than 0.07mg per g of common buckwheat grain, and that it is also highly likely that most adults would weigh considerably more than 60kg, and that most people have at least some melanin in their skin, combined with the fact that it is unlikely to eat more than 2kg of (cooked or uncooked) buckwheat per day, it seems reasonable to conclude that buckwheat grain is safe to consume either raw or cooked, so long as you are not allergic.  

Based on the above, it appears that buckwheat groats are safe to eat every day, either raw or cooked, in any amount you like.  

Pink flowered buckwheat setting seed

Eating buckwheat leaf, or rhizome, or sprouts, or flowers, may be a different story.  

While buckwheat leaves have been eaten as vegetables for thousands of years, and many millions of people still eat leaves, stems, flowers, and rhizomes of buckwheat regularly, they have almost exclusively been cooked in some way.  

There seems to have been some research conducted into raw leaves and stems as they have been used as animal fodder.  Unfortunately, while papers possibly exist, I have been unable to find any research into the fagopyrin content of cooked buckwheat leaves.  If you can direct me to a peer reviewed paper on this please let me know and I will update this blog post accordingly.  

I found an old paper stating that "based on a comparison to hypericin toxicity, the recommendable intake of buckwheat sprouts was estimated to be less than 40 g per day".  This statement is often quoted and is rather misleading at best.

The findings from that paper are regularly quoted when referring to the safe amount of raw buckwheat sprouts to eat.  People often extrapolate that to conclude the same safe limit applies to buckwheat leaves, or even groats, when this is not the case.  Strangely enough, the '40g per day' thing is not even the safe limit when dealing with buckwheat sprouts. 

Hypericin is a chemical found in St John's wort, it is similar to fagopyrin, but not the same.  Rats showed skin sensitivity when fed 0.5 mg kg hypericin, as opposed to fagopyrin which needs to be fed at 2.5-3mg per kg before any slight reaction is noticed.  

Given that studies indicate that hypericin is far less toxic than fagopyrin, I am not sure why this comparison was ever made, and it makes little sense as to why it is so often quoted.  If anything, this data would indicate that at least five times that amount (ie 40g x 5 = 200g) should be completely safe to consume regularly.  That paper also stated that raw buckwheat sprouts contained far higher levels of fagopyrin than leaves of mature plants.  

For these reasons I decided to ignore that often quoted 40 gram number and tried to do my own (also potentially flawed) calculations. 

Perennial 'golden' buckwheat autumn colours

The leaves of Tartary buckwheat have been recorded in one study as containing 0.512mg per gram.  This means it would be safe for a 60kg person to consume at least 292 grams of raw leaves per day for quite some time before any adverse effects would be possible.  

The same study recorded the fagopyrin content in common buckwheat leaves as 0.322mg per gram when in the vegetative phase, meaning it would be safe for a 60kg person to consume at least 465 grams of raw leaves every single day.  It is noteworthy that when in flower, common buckwheat leaves contained higher amounts of fagopyrin than they did before flowering.  Flowers contain significantly more fagopyrin than leaf and stem.  Most forage fed to animals has been from buckwheat that was flowering, which is partly why fagopyrism has been seen in livestock.  

In that same study, the leaves of perennial buckwheat were recording as containing up to 0.947mg per gram.  If it is safe for a 60kg person to consume over 150mg of fagopyrin per day, it would be safe to consume at least 158.39 grams of raw perennial buckwheat leaf every day before there could be possible issues.  While this is the lowest amount out of the three species, it is quite a lot of leaf to eat every day.  

It is noteworthy that several studies demonstrate there is a reduction in the amount of fagopyrin after steaming Tartary buckwheat seeds.  I can't find any papers indicating if fagopyrin levels of leaves are decreased with cooking.  I am also not sure why the fagopyrin was decreased from steaming.  I don't know if it is degraded by heat, or if some of it leaches out into the water and drips away.  While there is a lot I don't know, this is noteworthy nonetheless.  

Perennial buckwheat is used as a leaf vegetable

It is also noteworthy that the few cases of fagopyrism in humans I have read about were due to drinking copious amounts of 'green smoothies' made from raw sprouted buckwheat daily over a long time period.  Most of these reports did not specify if the hull was included in the green smoothie.  

These people reported tingling when sunbathing, most noticeable under their arms, some had tingling around their mouth, others were easily sun burnt, a few had rashes or even blisters after prolonged exposure to sunlight.  These people reported that simply reducing the amount of buckwheat sprouts in their smoothies was enough to eliminate this issue.  This means if you did over do it and ate too much for too long, it should not be difficult to reverse any issues that you may encounter.  

Based on the above, it appears that buckwheat leaves are safe to eat in moderation.  The amount that a person is likely to consume seems somewhat lower than the amount you would need to consume to encounter any issues, and to have any problems you would need to consume these large amounts over a significant amount of time.  If you eat a somewhat balanced diet, and not just buckwheat leaves (or lots of green smoothies), I think it would be difficult to reach the level where you could potentially encounter any issues.  

From the literature it appears there is next to no chance you could ever eat enough dehulled buckwheat groats to experience any issues with fagopyrism, and that leaves are safe to eat in moderation.