Do Tiger Nuts Have Health Benefits? We Review The Research

Introduction

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 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. It is also marketed as an aphrodisiac.

There is no doubt that tiger nuts are growing in popularity in the western world and 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 an actual 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 100gm serving of tiger nuts contains the following:

  • energy 400 kcal
  • protein 6.67 gm
  • fat 23.33 gm
  • carbohydrate 63.3 gm
  • fibre 33 gm
  • sugar 30 gm
  • calcium 100 mg and
  • iron 10 mg (2)

Tiger nuts are rich in alkaloids, flavinoids, phenolics, tannins, vitamin E and vitamin C.

Before we get carried away with excitement about tiger nuts, let it be also 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 impairs their absorption. Not so cool.

Tiger nuts can be eaten either raw or roasted, ground into a flour or 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 till valid!)

Are Tiger Nuts High In Fiber?

Tiger nuts contain on average 33 gms of fibre per 100 gms of tiger nut (2). The fibre content of tiger nuts is evenly divided  soluble and non-soluble fibre.

It is commonly said that the fibre content of tiger nuts compares favourably to that of other nuts. As an example, compare the 33 gms of fibre in tiger nuts to cashew nuts which have only have 0.9 gms of fibre per 100 gms.

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 actually have less fibre than bran which has 42 gms of fibre per 100 gms.

The relevance of this is the fact that tiger nuts costs $1.06 per ounce as compared to $0.17 per ounce of bran.

Bottom line: Bran is a cheaper and richer source of fibre than tiger nuts.

Is Tiger Nut Milk a Viable Substitute for Cow’s Milk?

There is growing interest in tiger nut milk as a soya free health drink (4). Tiger nut milk is a popular non-alcoholic drink (horchta de chufa) which has an annual economic impact of 60 million euro. 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 options 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 has 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’ 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 interest in extending the shelf-life of tiger nut and blending it with other plants.

Bottom line: Tiger nut is not a viable or  price comparable substitute to cow’s milk at present.

Are They High in Magnesium?

There is an  average of 100 mgs of magnesium per 100 gms of tiger nuts (6)

The recommended daily intake of magnesium for healthy adult is 400mg. 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.

Bottom line: 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 gm of tiger nuts (6).

Dietary deficiency of potassium is rare. Because of this, there is no specific recommended daily allowance for potassium.

Bottom line: The potassium content of tiger nuts is not clinically relevant to individuals with normal renal function.

Is it 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 not need to supplement with food sources of omega-9.

Bottom line: Tiger nuts are a rich source of omega-9 which is a nonessential fatty acid as our bodies can make this fatty acid.

Will it 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 fibre from fruit juice versus tiger nut milk. All sources of dietary fibre reduced cholesterol absorption but the pomegranate juice was the most effective at preventing cholesterol absorption.

A study showed that adding tiger nut fibre 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 fibre for a healthier burger.

Bottom line: 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 it 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 inhibited 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.

Bottom line: There are no clinical studies looking at tiger nuts in diabetes.

Is it 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 behaviour 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 mount 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.

Bottom line: Rodent students suggest that tiger nuts may have aphrodisiac properties but there are no human clinical studies yet.

Does it have antibacterial activity?

Laboratory studies suggest that tiger nuts have antibacterial activity against a range of food borne 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.

Bottom line: Tiger nuts are currently unproven as anti-infective agents in human subjects.

Other Research

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 chemo protective benefits (16).

There is also 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 for 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 of were contaminated with feces from soil  (19). Gross.

Bottom line: Tiger nuts are not quite as ‘safe’ as the marketing would have you believe.

Conclusion

A a physician, I have a huge problem with the tiger nut craze.

In summary:

  • it is a more expensive form of fibre 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 and
  • 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 cheese burger with fries as long as you wash it down with a ‘horchta de chufa’ milk shake. That makes no sense at all.

No wonder Christopher Columbus left the tiger nuts at home.

References

  1. De Castro O, Gargiulo R, Del Guacchio E, Caputo P, De Luca P. A molecular survey concerning the origin of Cyperus esculentus (Cyperaceae, Poales): two sides of the same coin (weed vs. crop). Ann Bot. 2015 Apr;115(5):733-45. doi: 10.1093/aob/mcv001. Epub 2015 Feb 17. PMID:
  2. www.ndb.nal.usda.gov
  3. Odumodu CU Antinutrients content of some locally available legumes and cereals in Nigeria. Trop Geogr Med. 1992 Jul;44(3):260-3.
  4. Aguilar N, Albanell E, Miñarro B, Guamis B, Capellas M. Effect of tiger nut-derived products in gluten-free batter and bread. Food Sci Technol Int. 2015 Jul;21(5):323-31. doi: 10.1177/1082013214535615. Epub 2014 May 22.
  5. Rubert J, Monforte A, Hurkova K, Pérez-Martínez G, Blesa J, Navarro JL, Stranka M, Soriano JM, Hajslova J. Untargeted metabolomics of fresh and heat treatment Tiger nut (Cyperus esculentus L.) milks reveals further insight into food quality and nutrition. J Chromatogr A. 2017 Sep 8;1514:80-87. doi: 10.1016/j.chroma.2017.07.071. Epub 2017 Jul 23.
  6. Bado S, Bazongo P, Son G, Kyaw MT, Forster BP, Nielen S, Lykke AM, Ouédraogo A, Bassolé IH. Physicochemical Characteristics and Composition of Three Morphotypes of Cyperus esculentus Tubers and Tuber Oils.
  7. https://healthybutsmart.com/magnesium-supplements-health-benefits/
  8. Yang Z, Ji H, Liu D. Oil Biosynthesis in Underground Oil-Rich Storage Vegetative Tissue: Comparison of Cyperus esculentus Tuber with Oil Seeds and Fruits.Plant Cell Physiol. 2016 Dec;57(12):2519-2540. Epub 2016 Oct 13.
  9. López-Marcos MC, Bailina C, Viuda-Martos M, Pérez-Alvarez JA, Fernández-López J. Effects of various fibre-rich extracts on cholesterol binding capacity during in vitro digestion of pork patties. Food Funct. 2015 Nov;6(11):3473-8. doi: 10.1039/c5fo00709g. Epub 2015 Aug 21.
  10. Sánchez-Zapata E, Muñoz CM, Fuentes E, Fernández-López J, Sendra E, Sayas E, Navarro C, Pérez-Alvarez JA Effect of tiger nut fibre on quality characteristics of pork burger. Meat Sci. 2010 May;85(1):70-6. doi: 10.1016/j.meatsci.2009.12.006. Epub 2009 Dec 11.
  11. Sabiu S, Ajani EO, Sunmonu TO, Ashafa AOT. KINETICS OF MODULATORY ROLE OF <i>Cyperus esculentus</i> L. ON THE SPECIFIC ACTIVITY OF KEY CARBOHYDRATE METABOLIZING ENZYMES. Afr J Tradit Complement Altern Med. 2017 Jun 5;14(4):46-53. doi: 10.21010/ajtcam.v14i4.6. eCollection 2017.
  12. Mahera N Al-Shaikh, Tala. A. L. Abdul Wahab, Sahar H Abdul Kareem, Salim R Hamoudi Protective effect of Chufa Tubers (Cyperus esculentus ) on induction of sperm abnormalities In mice treated with lead acetate” Int. J. Drug Dev. & Res., April-June 2013, 5(2): 387-392. doi: doi number www.ijddr.in/drug-development/protective-effect-of-chufa-tubers-cyperus-esculentus–on-inductionof-sperm-abnormalities-in-mice-treated-with-lead-acetate.php?aid=6845
  13. Allouh MZ, Daradka HM, Abu Ghaida JH. Influence of Cyperus esculentus tubers (tiger nut) on male rat copulatory behavior. BMC Complement Altern Med. 2015 Sep 23;15:331. doi: 10.1186/s12906-015-0851-9.
  14. Prakash N1, Ragavan B. Phytochemical observation and antibacterial activity of Cyperus esculentus L. Anc Sci Life. 2009 Apr;28(4):16-20.
  15. Onuoha NO, Ogbusua NO, Okorie AN, Ejike CECC. Tigernut (<i>Cyperus esculentus</i> L.) “milk” as a potent “nutri-drink” for the prevention of acetaminophen-induced hepatotoxicity in a murine model. J Intercult Ethnopharmacol. 2017 Jun 9;6(3):290-295. doi: 10.5455/jice.20170603094811. eCollection 2017 Jul-Sep.
  16. Hamdy SM, Sayed ON, Abdel Latif AKM, Abdel-Aziz AM, Amin AM. Hesperidin and tiger nut reduced carcinogenicity of DMBA in female rats. Biomed Pharmacother. 2016 Oct;83:718-724. doi: 10.1016/j.biopha.2016.07.032. Epub 2016 Jul 29.
  17. González-De-Olano D, González-Mancebo E, Mohedano-Vicente E, Gandolfo-Cano M, Bartolomé B Pollen-food syndrome involving allergy to tiger nut. J Investig Allergol Clin Immunol. 2013;23(3):197-8. No abstract available.
  18. Sebastià N, El-Shenawy M, Mañes J, Soriano JM. Assessment of microbial quality of commercial and home-made tiger-nut beverages. Lett Appl Microbiol. 2012 Apr;54(4):299-305. doi: 10.1111/j.1472-765X.2012.03212.x. Epub 2012 Feb 29.
  19. Ayeh-Kumi PF, Tetteh-Quarcoo PB, Duedu KO, Obeng AS, Addo-Osafo K, Mortu S, Asmah RH. A survey of pathogens associated with Cyperus esculentus L (tiger nuts) tubers sold in a Ghanaian city. BMC Res Notes. 2014 Jun 6;7:343. doi: 10.1186/1756-0500-7-343.
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Do Tiger Nuts Have Health Benefits? We Review The Research
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Do Tiger Nuts Have Health Benefits? We Review The Research
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Healthy But Smart

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