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One of the latest health fads is tiger nuts. The tiger nut (Cyperus esculentus L.) is a plant of the sedge family and looks a bit like grass. The tiger nut is native to Valencia, Spain but also grows well in other temperate zones.
It was cultivated in ancient Egypt and dates back to at least the fourth millennium BC. Christopher Columbus does not get the credit for this one because he did not bring the tiger nut to the Americas.
Research shows that the tiger nut came to America via long-distance dispersal (i.e. pollination) long before the arrival of the famous Italian explorer (1). In fact, tiger nuts are known to have been used as a food source by both native Americans and the Maya.
There are lots of things that were popular in ancient civilizations that we have left behind us. So what is all the hype about tiger nuts these days? Tiger nuts are purported to be helpful for enhancing blood circulation, lowering cholesterol, preventing heart disease and thrombosis, in addition to reducing the risk of colon cancer. They are also marketed as an aphrodisiac.
There is no doubt that tiger nuts are growing in popularity in the western world. There are currently over 200 tiger nut-based products for sale on Amazon.
Is this self-indulgent exoticism or a proven functional food?
What Are Tiger Nuts?
Tiger nuts are also known as “zulu nuts,” “ground almonds,” “earth almonds,” “chufa,” and “edible rush.” (That last one sounds a bit like grass to me.)
It is a perennial herb that grows to a height of 90 cm. It is a crop plant but also grows in the wild as a weed. The tubers grow to the size of a peanut. There, I said it. That is the only connection between tiger nuts and actual nuts.
Technically, a tiger nut is not a nut. It has tubers at the base of rhizomes. This means that it classifies as a root vegetable and not a nut.
There are three main types of tiger nut based on color: yellow, brown, and black.
An average 100 g serving of tiger nuts contains the following:
- energy 400 kcal
- protein 6.67 g
- fat 23.33 g
- carbohydrate 63.3 g
- fiber 33 g
- sugar 30 g
- calcium 100 mg and
- iron 10 mg (2)
Tiger nuts are rich in alkaloids, flavonoids, phenolics, tannins, vitamin E, and vitamin C.
Before we get carried away with excitement about tiger nuts, let it be said that tiger nuts also contain anti-nutrients such as oxalate and tannins (3). These anti-nutrients chelate minerals such as iron, zinc, and calcium and impair their absorption. Not so cool.
Tiger nuts can be eaten either raw or roasted, ground into a flour, or drunk as a milk drink. In addition to human consumption, tiger nut is also an important food for livestock.
Is There Any Research?
There are only 500 research papers on the overall Cyperus species, but there is not a single human clinical trial on “Cyperus esculentus.”
To put this into context, there are over 12,000 published papers on peanuts, which include 300 human clinical studies. (Yes, I know that tiger nuts are not nuts, but the comparison is still valid!)
Are Tiger Nuts High in Fiber?
Tiger nuts contain on average 33 g of fiber per 100 g of tiger nut (2). The fiber content of tiger nuts is evenly divided in soluble and non-soluble fiber.
It is commonly said that the fiber content of tiger nuts compares favorably to that of other nuts. As an example, compare the 33 g of fiber in tiger nuts to cashew nuts, which have only have 0.9 g of fiber per 100 g.
The problem here is that cashew nuts are not actually nuts in the first place, which means we are not comparing like with like. So who cares?
Tiger nuts have less fiber than bran, which has 42 g of fiber per 100 g.
The relevance of this is the fact that tiger nuts cost $1.06 per ounce as compared to $0.17 per ounce of bran.
Bran is a cheaper and richer source of fiber than tiger nuts.
Is Tiger Nut Milk a Viable Substitute for Cow’s Milk?
There is a growing interest in tiger nut milk as a soya-free health drink (4). Tiger nut milk is a popular non-alcoholic drink (horchata de chufa) which has an annual economic impact of 60 million euros. That is a lot of euros.
One advantage of tiger nut is that the milk remains liquid when refrigerated. The major disadvantage of tiger nut milk is that it is considerably more expensive than other non-dairy milk alternatives. Soy milk retails at $0.09 per oz as compared to $0.73 for tiger nut milk. (No wonder it is a 60-million-euro business).
Attempts at ultra-high temperatures (UHT) to extend the shelf-life of tiger nut milk compromised the nutritional content of the milk as compared to the fresh product and is not a viable option at present (5).
Studies are ongoing to produce a protein-energy-rich milk from a combination of both soy and tiger nut. Soy has a high protein content but an astringent taste. Tiger nut has a high oil content but generally has a more acceptable flavor than soy. It is hoped that the combination would capture the best of both plant-based milk substitutes and offer a viable, affordable substitute to cow’s milk.
There are also ongoing studies on combining tiger nut milk with Hibiscus and Moringa to produce a palatable functional drink.
Given the fact that this is a 60-million-euro business, it is no wonder that there is such an interest in extending the shelf life of tiger nut and blending it with other plants.
Tiger nut is not a viable or price-comparable substitute to cow’s milk at present.
Are Tiger Nuts High in Magnesium?
There is an average of 100 mg of magnesium per 100 g of tiger nuts (6).
The recommended daily intake of magnesium for healthy adults is 400 mg. As mentioned above, tiger nuts contain anti-nutrients which chelate divalent cations such as magnesium, which may affect the absorption of the magnesium.
In any case, healthy individuals with a well-balanced diet are not at any risk of a clinically significant magnesium deficiency and do not need magnesium supplements (7). As such, the magnesium content of tiger nuts is not a selling point for these nuts.
The magnesium content of tiger nuts is not clinically relevant due to the presence of anti-nutrients, which limit the absorption of magnesium, and the fact that healthy humans do not need magnesium supplementation.
Are They High in Potassium?
There is an average of 608 mg of potassium per 100 g of tiger nuts (6).
Dietary deficiency of potassium is rare. Because of this, there is no specific recommended daily allowance for potassium.
The potassium content of tiger nuts is not clinically relevant to individuals with normal renal function.
Are They High in Oleic Acid and Does That Mean Anything?
Tiger nuts are a rich source of fat. Tiger nuts accumulate oil in the tubers via biosynthesis of triacylglycerols (8).
Studies have shown that the fatty acid breakdown of tiger nuts is as follows:
- oleic acid 64%
- palmitic acid 16% and
- linoleic acid 13% (6)
Oleic acid is a rich source of omega-9 fatty acids, which are believed to confer protection against cardiovascular disease by raising HDL (good cholesterol) and lowering LDL (bad cholesterol). Unlike omega-3 fatty acids, omega-9 fatty acid is a non-essential fatty acid. This means that your body can make omega-9 and you don’t need to supplement with food sources of omega-9.
Tiger nuts are a rich source of omega-9, which is a non-essential fatty acid as our bodies can make this fatty acid.
Will They Lower Cholesterol?
There is a laboratory-based study which looked at cholesterol binding during digestion of pork patties (9). The study compared the effect of dietary fiber from fruit juice versus tiger nut milk. All sources of dietary fiber reduced cholesterol absorption, but the pomegranate juice was the most effective at preventing cholesterol absorption.
A study showed that adding tiger nut fiber to pork burgers made them “less greasy and less juicy” (10). (As a vegetarian, I think this is pretty grim.) This led the authors to recommend tiger nut fiber for a healthier burger.
Technically, tiger nut has been shown to lower the absorption of cholesterol from fatty foods in vitro. It has to be said that recommending tiger nut for the absorption of fat from “greasy burgers” is missing the point entirely. To paraphrase a famous quote – “It’s not the tiger nut, stupid.” The problem here is the “greasy” burger. In no way should tiger nut be marketed to promote “greasy burgers.”
Will They Help Diabetics?
There is only one study looking at the effect of tiger nut on diabetes (11). The study was carried out in Nigeria and was a laboratory-based study. The study showed that tiger nuts inhibit enzymes that convert carbohydrates to glucose. This delayed glucose absorption and reduced post-prandial hyperglycemia.
There are no clinical studies evaluating this enzyme inhibition in humans.
There are no clinical studies looking at tiger nuts in diabetes.
Are They an Aphrodisiac?
Tiger nuts are used as aphrodisiacs in Ayurvedic medicine. In Arabic, the tiger nut is known as “Hab Al-zulom,” which translates into “the seeds of men.” Intriguing.
There are two studies looking at the aphrodisiac properties of tiger nuts.
The first study showed that tiger nuts increased both testicular weight and spermatogenesis in mice (12).
A second study examined the copulatory behavior of rats (13). The study divided the rats into highly active and moderately active, based on their baseline sexual activity. (You could not make this stuff up.)
The study found that tiger nut stimulated sexual motivation in both groups. You may well be asking yourself how this was decided. Well, the investigators noted a “reduced amount and intermission latency” in these rats as compared to controls. Additionally, sexual performance was improved as evidenced by increased “intromission frequency.”
No, please don’t even think of asking me – you can’t volunteer because there are no human trials planned at this time.
Rodent studies suggest that tiger nuts may have aphrodisiac properties, but there have been no human clinical studies yet.
Do They Have Antibacterial Activity?
Laboratory studies suggest that tiger nuts have antibacterial activity against a range of foodborne pathogens such as Salmonella, Proteus, E coli. Klebsiella, and Pseudomonas (14).
To date, there are no clinical studies looking at the effect of tiger nuts as an anti-infective in human subjects.
Tiger nuts are currently unproven as anti-infective agents in human subjects.
A study showed that tiger nuts helped protect against liver damage in 25 rats who were given toxic doses of acetaminophen (15).
Laboratory-based rat studies compared hesperidin derived from citrus fruit to tiger nut and found that hesperidin offered better antioxidant and chemoprotective benefits (16).
There is also an interest in using tiger nuts as biodiesel fuel.
Are Tiger Nuts Safe?
Tiger nuts are often advertised as being allergy-free. This is simply not true of anything. Cases of tiger nut allergy have been reported, especially in people who are allergic to pollen (17).
There are numerous reports of contamination of tiger nuts with aflatoxin, Aspergillus, animal foreigns, and stones. Tiger nuts bought at the roadside have also been found to be contaminated with fecal pathogens such as Proteus, Salmonella, and Shigella (18). This suggests that they were either irrigated with contaminated water or were contaminated with feces from soil (19). Gross.
Tiger nuts are not quite as “safe” as the marketing would have you believe.
As a physician, I have a huge problem with the tiger nut craze.
- it is a more expensive source of fiber than regular bran
- it is marketed as being rich in magnesium, potassium, and oleic acid, but we don’t need to supplement any of these
- it poses a very significant risk of infection
- It has been shown to have aphrodisiac potential in rodents, but this is unproven in humans. It has also been shown to be contaminated with Fifty Shades of Feces. The very thought is an anti-aphrodisiac.
I have to admit that I have nothing against the odd bit of self-indulgent exoticism myself. I do have a huge problem with promoting poor health by suggesting that you can eat a triple cheeseburger with fries as long as you wash it down with a “horchata de chufa” milkshake. That makes no sense at all.
No wonder Christopher Columbus left the tiger nuts at home.