The Medicinal Uses of Poi

Abstract

INTRODUCTION

Very few studies have researched or explored the possibility of poi being utilized in medical nutrition therapy for certain health conditions. Early studies in the mid 1960s¹ implied that poi might be useful for the treatment of allergies and failure-to-thrive in infants. These studies were conducted in Hawaii, where researchers reported that many hospitals used poi on a regular basis in the early 1950s.¹ This paper reviews health problems—allergies, failure-to-thrive, and certain gastrointestinal conditions such as diarrhea, gastroenteritis, irritable bowel syndrome, and inflammatory bowel disease (Crohn’s disease and ulcerative colitis)—for which poi might be a useful food substitute. Probiotics might also benefit cancer, depressed immune function, inadequate lactose digestion, cancer cachexia, AIDS, and pancreatitis/cystic fibrosis (Table 1).²

TARO PLANT

The historic use and importance of taro (the plant from which poi is made) can help explain why this crop has such significant implications in human health. Taro (Colocasia esculenta L.), a root crop belonging to the Araceae family, has been cultivated for many centuries. Originating in Asia, taro is now primarily found in tropical and subtropical regions,^3,4 where it was historically a major dietary staple on the islands of the Pacific, especially Hawaii, New Zealand, and west to Indonesia. This plant provided primarily carbohydrates, along with a few other nutrients (Table 2).⁵ The Polynesians gave over 200 names to the different varieties (or cultivars) of taro, and they were believed to carry this important crop with them as they journeyed to other islands. Taro was extremely important to the Hawaiians who associated it with their Gods and their story of creation, and even used it for medicinal purposes.

DEFINITION OF POI

Poi is now the most common food form of taro consumed in Hawaii. It is made by cooking taro corms and then crushing/pounding them into a starchy paste by adding water.⁶ The amount of water used determines the thickness of poi, which is then strained through a cloth.⁷ Yeast and lactic acid bacteria naturally found on the plant’s surface ferment the mixture, eventually leading to “sour” poi.⁸ Fermentation proceeds without inoculated starter cultures and usually takes about two to three days to reach the “sour” stage.⁸ The fermentation of fresh poi is similar to that occurring in the preparation of yogurt and sauerkraut. In poi, acid production changes the pH from 6.3 to 4.5 within 24 hours, and reaches its lowest pH on the fourth or fifth day of fermentation, when the poi is usually discarded. As early as 1933, Allen and Allen⁹ recognized that souring was the result of acid-producing bacteria such as Lactobacillus and Streptococcus. These researchers were able to identify three Lactobacillus species and two Streptococcus (recently renamed Lactococcus) bacteria, which included the S. lactis species.⁹ In a recent study, Huang⁸ identified the predominant species in sour poi as Lactococcus lactis. Despite its acidic pH, poi and taro are considered alkaline foods because their alkaline-forming elements (Na, K, Ca, Mg) exceed their acid-forming elements (S, P, Cl).¹

Poi is easily digested, and this may benefit certain health conditions involving the gastrointestinal tract (Table 3).^10–14 In 1928, Barret¹⁵ observed that the Kanakan language of the Polynesians did not even have a word for indigestion. MacCaughey¹⁰ recognized how easily poi was digested in 1917, and explained that this was due to the small size of the taro starch granule. This was confirmed by the studies of Langworthy and Deuel,¹¹ who found that the raw starches of rice and taro root were notably more digestible; they also determined that this was the result of the smaller size of the starch granules.¹¹ Early human studies with poi ingestion showed no undigested starch in feces, even if large quantities of poi were consumed.⁹ In 1952, Derstine and Rada¹ reported that the fermentation process seems to be affiliated with the easy digestibility of poi and the high absorbability of its minerals, such as calcium and phosphorus. The nutrient composition of poi is very similar to the values shown for taro (Table 2).⁵ Poi is also hypoallergenic because of its very low protein content, and as such has been used as a food substitute for people with food allergies.

POI AS A FOOD SUBSTITUTE FOR INFANT ALLERGIES

In 1939, Alverez¹⁶ was the first to suggest that poi be used as a substitute for people with allergies. It is interesting that in the United States, allergies are most often caused by corn and wheat, while in Japan, allergies are most often caused by rice.¹⁷ During World War II, poi was used as a substitute for cereal or grain in Honolulu among soldiers experiencing allergy problems.¹ Dr. Lawrence J. Halpin, a physician specializing in allergies, was satisfied with the use of poi as a substitute for cereals, and upon returning to the mainland, he attempted to get other doctors interested in poi for their wheat- and grain-sensitive patients. However, mainland doctors were reluctant to use poi because of their unfamiliarity with the product or its use. Another concern was that a few physicians did not consider poi sufficiently sterile as an infant food or for therapeutic use.¹

Food allergies most frequently afflict children,¹⁸ with cow’s milk being the most common allergenic food for infants, followed by eggs, peanuts, tree nuts, and soybeans.¹⁹ Feingold²⁰ was one of the first researchers to suggest that poi be considered a substitute for soy milk in infants allergic to both soy and cow’s milk. Cereals can also cause allergies in infants because they usually are the first semi-solid food consumed. The most common method of treatment for food allergies is the elimination diet, in which the specific food is avoided or eliminated.²¹ This approach can be difficult because not many alternative medical foods are available, and many infants develop allergies to the substitutes that are given.²¹ Physicians in Hawaii were some of the first researchers to investigate other substitutes for food allergies.

Dr. Jerome Glaser, a pediatrician and allergist visiting the Hawaiian Islands in 1961, reported that many infants in Hawaii were practically raised on poi.⁷ In addition to the extensive use of poi for normal infants, Glaser noted the high use of poi for allergic infants and those with gastrointestinal disorders, and theorized that infants allergic to cereal could eat poi as a substitute. Glaser attempted to conduct a 6-month study of 100 infants born in the Strong Memorial Hospital, in which 50 infants were to be fed poi and compared with 50 rice-fed babies. However, parental compliance was a problem, and the study was reduced to only three babies remaining on the rice cereal for 6 months and five babies on the poi diet. However, Glaser realized that 6 months was an impractical time period and that 2 months was probably sufficient to establish trends. Nineteen rice-fed babies and 28 poi-fed babies were in the study for 2 months. After looking at several growth curves, Glaser et al.⁷ concluded that the development of full-term poi-fed babies was not discernible from that of rice-fed babies. Additional observations were that only three of the 22 poi-fed babies (14%) had hematocrits that were 30 or less, compared with three out of 11 rice-fed infants (27%). As far as these researchers could determine, both groups of infants thrived equally well. They were unable to have full control over these infants, however, and complete metabolic studies could not be performed in an outpatient clinic.⁷

Roth et al.¹³ supported Glaser’s findings when they conducted their study on infants in Honolulu hospitals. They tested 191 potentially allergic infants (59 infants were omitted from the study) and found that breastfed babies remained completely symptom-free. Of the infants fed cow’s milk substitutes (n = 132), about 7% of the rice-fed infants (4/55) and poi-fed infants (5/73) showed signs of allergy. Roth concluded that poi was definitely well tolerated by babies, and that it may be regarded as a useful alternative when there is a family history of cereal allergy.¹³

Glaser et al.⁷ also reported two case studies in which poi proved to be helpful to allergic infants. One infant could not tolerate cow’s milk, soybean milk, meat-based milk, any cereals, or any other foods, but thrived well on poi. This infant was a boy who was first seen at the age of 9 weeks. He was hospitalized because he was considered a failure-to-thrive infant as the result of having multiple food intolerance. His weight was 3700 grams at the time of admission. A family history of allergy resulted in his being placed on a diet of soybean milk. The soybean milk did not produce the desired weight gain effects, so they turned to many other formulas, including goat’s milk, beef- based milk from Gerber, and a lamb-based milk. The lamb-based milk produced some results but he still had loose stools that they controlled with diodoquin. At the age of 9 months, he was able to take in banana flakes, the lamb-based milk, small quantities of chicken, tapioca, and pears, as well as a vitamin preparation. His stools then became soft and contained a lot of mucous, which the diodoquin did not seem to help. He also developed atopic dermatitis. At this time, the lamb-based milk was discontinued, which resulted in control of the soft stools. He was started on poi as the main dietary carbohydrate, which he had no trouble tolerating. He was given whale meat as a source of protein and calcium, and was later given rabbit meat and goat meat. By the age of 19 months, he was at the lower limit of weight for his height (11.5 kg). Once again, he had loose stools, so the foods that were suspected were only given once or twice per week—a method called a rotary diversified diet—which appeared successful. His intake of poi was approximately one pound per day. This child was so sensitive that at 2 years old he developed mild ragweed pollinosis and had a mild anaphylactic reaction to a bee sting, as well as a number of allergic drug reactions. He was last seen at the age of 4 years and 3 months, at which time he had a normal weight and height for his age, appeared healthy, and was still consuming large amounts of poi.⁷

The second case study by Glaser et al.⁷ using poi in allergic children consisted of an edematous girl who was extremely ill and admitted to the hospital at the age of 2.5 years. She had come from a family with a history of allergy and had already experienced gastrointestinal problems as an infant that were attributed to cow’s milk allergy. In infancy, she had also experienced attacks of spasmodic croup, which had progressed into bronchial asthma. She was so sick that she could not even be skin tested to determine the cause of the edema. She was placed on an elimination diet with meat-based milk as the sole protein source, poi as the cereal alternative, banana, applesauce, string beans, carrots, and a vitamin supplement. Her diet remained fairly constant for the next 9 months. She began to develop a taste for poi mixed with banana or applesauce and consumed roughly 13 ounces per day. Although her edema persisted and was found to be the result of congenital lymphangiectasia, her allergic symptoms became minimal. When last seen at 4.5 years old, she was tolerating many foods well, had eliminated cow’s milk completely, and was using a meat-based milk.⁷

Poi may also be useful for people with celiac disease, who are allergic to the protein gluten in wheat. Although it has been suggested that the lack of gluten in poi makes it an ideal substitute for cereals in patients with celiac disease, there are no reported formal studies in the literature. This may be partially due to the rarity of this condition in Hawaii, as this condition more frequently afflicts Caucasians than Asians.⁷

FAILURE-TO-THRIVE

Weight gain is often the desired outcome for patients with failure-to-thrive. Few studies have been done on the use of poi and failure-to-thrive, and those that exist date back to the mid 1960s. In Glaser’s research studying allergic infants in 1965,⁷ there were 12 preterm infants (those who remained in the hospital for 11 to 45 days) that consumed poi and thrived as well as other preterm infants of comparable weight and size.⁷ There was also a case study of a premature infant who was the second born of a non-identical twin pair and weighed 1500 grams.⁷ After being on various formulas and only gaining 100 grams in 54 days, she had failed to thrive. Thorough examinations and tests had been conducted, including gastrointestinal x-rays, sweat electrolytes, carbohydrate utilization tests, and blood chemistry tests, all with negative results. She was then given poi and quickly responded positively. Glaser et al.⁷ mention that she was discharged from the hospital after being able to maintain a healthy weight (2250 to 2500 grams), but does not state her weight at the time of the discharge. Her progress was followed for 19 weeks following discharge, but unfortunately, she never returned to the hospital and was lost to follow-up. Although Glaser was careful in his statement of poi being the cause of this baby’s transformation, he stated “It is a matter of common experience that any food tolerated by a premature infant is equally well or better tolerated by a full-term infant. We feel that poi can safely be recommended as a food for any very young infant.”⁷ However, because these studies occurred almost half a century ago, further research investigating the use of poi in infants and children are warranted.

CONCLUSION

Although a few studies several decades ago suggest the use of poi in treating certain medical conditions, especially infant food allergies and failure-to-thrive in infants, studies involving poi after that period declined dramatically. The studies in the mid-1960s evaluating poi’s usefulness in treating allergies and effecting weight gain in failure-to-thrive infants were helpful, but more studies need to be conducted to counter or confirm their results.

Another potential medicinal use of poi is as a probiotic because it contains the predominant lactic acid bacteria (L. lactis). Perhaps poi also deserves to be researched as having a possible beneficial role in those medical conditions shown to improve with the use of fermented dairy products: diarrhea, gastroenteritis, irritable bowel syndrome, and inflammatory bowel disease (Crohn’s disease and ulcerative colitis), cancer, depressed immune function, and inadequate lactase digestion.

In addition, the easy digestibility and other characteristics of poi might make it a nutritional supplement for weight gain in patients with conditions such as failure-to-thrive, cancer cachexia, AIDS, pancreatitis (cystic fibrosis), and some of the induced weight loss conditions of the gastrointestinal tract, such as inflammatory bowel disease. It is suggested that poi, a nutritional supplement unique in its possible probiotic activities and low allergenic protein, should be further investigated for possible benefits to patients affected by these medical conditions.

Acknowledgments

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