_____________________________________________________ The Correlation between Cancer Incidence and Kava Consumption Gregory G. Steiner DDS, MS A number of countries in the South Pacific have very Background. Table 1.— Age-standardized cancer incidence rates for all sites of the population low cancer incidence. In spite of a high percentage males and females per 100,000 population habituated to tobacco, the cancer incidence in countries such as Vanuatu and Fiji experience age-standardized cancer incidence in Country Incidence male Incidence female the 70’s. A number of studies have noted the low cancer incidence in these countries and have postulated that a dietary chemopreventive Vanuatu 70.9 83.7 1198-77990. agent might be responsible. Fiji2 75.0 112.2 (19791982) 3 90.2 93.7 Methods. The cancer incidence studies for the Pacific Islands were Western Samoa (1980.1988) completed in the 1980’s. During this time period accurate records Micronesia4 132.9 97.0 allow for a calculation of local kava consumption. This study (1980-1982) 5 182.0 154.0 compares the cancer incidence for a number of Pacific Island New Caledonia (977-1981) Nations with local kava consumption. Hawaii/Hawaiians6 3119* 297.6* (1978-1982) 6 322.9* 297.6* Results/Conclusions. The data indicates that the more kava con New Zealand/Maoris 10.8-1*80. the cancer incidence for that sumed by a population the lower 6 307.2* 276.2* USA. Los Angeles population. The data suggests there is a close inverse relationship (1978-19821 * between cancer incidence and kava consumption. all sites but 173 (other skin) Introduction In 1995 Le Marchand et al published a study on diet and lung science. 7 This study was population-based case- Cancer prevention is now a well-established medical cancer in the South Pacific. Chemoprevention has been described as the intervention with spe controlled using data from Caucasian. Japanese Hawaiian, Filipino cific agents to prevent, inhibit or reverse carcinogenesis before and Chinese groups to investigate the role of diet in explaining lung malignancy. At this time there is a concerted effort to find effective cancer incidence. He concluded much of the difference in lung chemopreventive agents for cancer and also to subject these agents cancer incidence was explained by smoking and the chemopreventive to mechanistic studies to determine their mode of action. properties of lutein. He found that a very high number of Fijians The South Pacific Commission Cancer Registry was established smoked but they smoked fewer cigarettes. The number of cigarettes in 1977. Many South Pacific Nations have significantly lower sold in Tahiti was used to confirm the data. In rural areas of the South cancer incidence than other parts of the world. Table 1 lists the age- Pacific tobacco is a cultivated crop and tobacco is commonly sold standardized cancer incidence rates for males and females in the loose in local markets. It is possible the number of cigarettes Pacific Island Nations with Los Angeles Caucasians as a reference. consumed in Fiji is higher when local production and consumption In 1985 Henderson et al published a paper on the cancer incidence of tobacco is calculated. However, when Le Marchand et al con in the islands of the Pacific. He noted the high rate of smoking among ducted the survey the amount of cigarettes consumed by Fijians was Fijians and postulated the low cancer incidence might be related to recorded and is assumed to be accurate. Le Marchland et al was chemopreventive actions of certain vitamins and trace elements unable to completely explain the low lung cancer incidence and 4 Paksoy et al studied the cancer incidence in proposed that the difference might be related to the chemopreventive found in the diet. Western Samoa and also summarized other cancer incidence studies actions of certain vitamins and trace elements in the diet. 3. In conclusion Paksoy et al also Another possible explanation for the low cancer rates in Vanuatu, for countries throughout the Pacific proposed that dietary protective factors might be responsible for the Fiji, Western Samoa, and Micronesia could be the consumption of low cancer rates found in some South Pacific Nations. kava. Kava (Piper methysticum) is a plant indigenous to the Pacific Islands. All major Pacific Islands developed kava as a beverage and it is commonly consumed much like alcohol in western culture. Correspondence to: However, western intervention has resulted in a significant reduc Gregory G. Steiner DOS, MS POBox6l5l5 tion and sometimes the complete cessation of kava drinking in some Honolulu, HI 96839 HAWAII MEDICAL JOURNAL, VOL 59, NOVEMBER 2000 420 of males and females South Pacific Islands. Kava is traditionally prepared from the root of There is no information on what percentage Men will often stop at the the plant, which is worked in water to extract the active ingredients. drink kava in the countries being studied. kava with friends. While The active ingredients have been identified to be a group of com kava bar after work and enjoy bowls of of kava consumption is by pounds known as kavapyrones or kavalactones, women often drink kava the majority of people drink The commonly accepted actions of kava, which are referenced in men. We have no information on what percentage 9, eupho kava or what percentage of men or women drink kava.. Because 8, antidepressant the literature, are as an anti-anxiety agent 3. Kava kava consumption is believed to vary significantly for women in 2. and anti-convulsant’ riant’°. muscle relaxant”, analgesic’ used for comparison. As has become popular in the west as an anti-anxiety agent. No side each culture the cancer rate for males was for cancer rates and effects have been identified when used on a daily basis in moderate discussed earlier the most accurate numbers Therefore the amounts.’4 kava consumption is from data gathered in the 1980’s. population figures that were used to calculate the kava consumption Materials and Methods per person is based on figures form l989.’ The cancer incidence studies for the Pacific Islands were com pleted in the 1980’s (TABLE 1). During this time period we also ResultslDiscussion kilograms of kava consumed have the most accurate records of local kava consumption. Vanuatu Table 2 lists the cancer incidence and greater the amount of kava recognized the potential of kava as an export crop and conducted a in each country. In every country the 5 With the consumption the lower the cancer incidence. The data from table 2 study in 1984 to count the plants growing in that country.’ is not charted due to exception of Vanuatu, prior to the 1990’s, all production of kava can is displayed in chart 1. The Kingdom of Tonga the cancer incidence for this be considered to be for local consumption. The kava production for the author’s inability to determine between cancer inci Fiji, Western Samoa and Micronesia is primarily for local consump country. There is a close inverse relationship 6 In the 1990’s kava became a dence and kava consumption. tion at least until the early 1990’s.’ 6 During the mid 1990’s significant export crop for Vanuatu and Fiji.’ there was a significant increase in plantings of kava and also sporadic harvesting of kava due to price fluctuations. For these Table 2 reasons the data presented is from the 1980’s in an effort to produce the most accurate figures on the amount of kava consumed in the Country Population Kilograms Cancer rate! Kilograms! 100,000 males person various Pacific Island Nations.. 1989 consumed In the 1980’s Vanuatu was the primary exporter of kava. It is estimated that 20% of the production was exported outside the Vanuatu 155,000 1,042,252 70.9 6.7 unknown 4.0 The remaining 80% ofVanuatu’s kavaproduction is consid Tonga 100,000 400,000 Pacific. 2,100,000 75.0 2.8 figures used to Fiji 749,000 ered to be consumed locally. Irrespective of the Western Samoa 180,000 400,000 90.2 2.2 calculate the kava consumption in Vanuatu, it is obvious that this Micronesia 108,000 150,000 132.9 1.4 182.0 0.6 country’s kava consumption per person far exceeds any other New Caledonia 161,000 100,000 Hawaiians 208,476 0 311.9 0.0 country. Reliable estimates are available for the number of6plants being cultivated in Vanuatu, Fiji, Western Samoa, Tonga and Micronesia.’ In 1984 Vanuatu counted the number of plants being cultivated, Chart 1.—Comparison of Cancer Incidence and Kava Consumption 5 The number of hectares of kava which totaled 2,605,635 plants.’ plants being cultivated totaled 4,200 hectares in Fiji, 800 hectares in Western Samoa, 800 hectares in Tonga and 300 hectares in Micronesia.’6 New Caledonia does not cultivate kava but imports approximately 100 tons of kava each year. Each hectare of cultiva c) 5 On average kava plants are to hold 1000 plants.’ tion is estimated C 5 The average plant when harvested after four years and replaced.’ 5 When fresh harvested yields ten kilograms of fresh rootstock.’5 rootstock is dried it retains 20% of it original weight.’ 0) Therefore, 0) Kava plants on average are harvested after four years. C-, 0) each year 25% of the plants are processed. Each plant produces an -C CiC average of 10 kilograms offresh rootstock, which, when dried yields a) dried rootstock. The following formula provides us with C-)C 2 kilograms 0) the amount of kilograms of dried kava root consumed each year. C) kava consumption on kilograms per year kava root = kg consumed per year Number of plants X 2 kg dry cancer!lOOk vs.