Dr. Mathews et al 1988 Study - One of the sources where all this negative information is coming from.
Today we’re going to focus on one study. This study is “Effects of the heavy usage of kava on physical health: summary of a pilot survey in an aboriginal community”. The main author of this study is John D. Mathews. Prof. Mathews works at the Melbourne School of Population and Global Health. He works in the Medicine, Dentistry, and Health Sciences division. His research expertise includes: Epidemiology, biostatistics, mathematical modeling, genetic epidemiology, Aboriginal health, transmissible spongiform encephalopathies, herbicides and cancer, radiation and cancer, and public health policy [1]. He, along with his co-authors, assessed health artifacts seen in 39 individuals in Arnhem Land. It should be understood that the author was simply reporting what they saw, and making the best conclusions with the data they had at the time. In 1988 not much was known about the overall health effects of kava and all we had to draw on was empirical data.
I want to focus on this because through the years this study alone is referenced as proof of liver harm, and various other issues that are more likely related to the population that was studied, than anything to do with kava. The authors themselves specifically acknowledge this fact in a follow up from letters to the author [15].
The Study:
In 1987-1988 39 Kava consumers and 34 non-users were studied in Arnhem Land. Of these current users 20 (27%) were classified as “very heavy users” at 440g/week, 15 (21%) were classified as “heavy users” at 310g/week, and 4 (5%) were classified as occasional users at 100g/week.
Instead of attempting to re-word this, it’s best you just read it word-for-word as it is written.
Health Harm Claims of this article:
Let’s address these one at a time.
Low BMI
Decreased lymphocyte count.
With all of that said, it should be obvious now that the study was plagued with confounding factors introduced by the group of people being studied. Mathews himself even backs this up in his response to letters to the authors. He states “At no stage have we suggested that kava is the sole cause of the health problems that were described; in particular, it is likely that malnutrition is an important cofactor [15]”.
[1] Prof John Mathews - University of Melbourne. (n.d.). Retrieved January 31, 2022, from https://findanexpert.unimelb.edu.au/profile/29800-john-mathews
[2] Rychetnik, Lucie, and Christine M. Madronio. 2011. “The Health and Social Effects of Drinking Water-Based Infusions of Kava: A Review of the Evidence.” Drug and Alcohol Review 30 (1): 74–83. https://doi.org/10.1111/j.1465-3362.2010.00184.x
[3] Gwynn, Josephine, Kyra Sim, Tania Searle, Alistair Senior, Amanda Lee, and Julie Brimblecombe. 2018. “Effect of Nutrition Interventions on Diet Related and Health Outcomes of Aboriginal and Torres Strait Islander Australians: A Systematic Review.” BMJ . https://doi.org/bmjopen-2018-025291.
[4] Salazar-Muñoz, Yolocuauhtli, G. Angelina López-Pérez, Blanca E. García-Caballero, Refugio Muñoz-Rios, Luis A. Ruano-Calderón, and Leonardo Trujillo. 2019. “Classification and Assessment of the Patelar Reflex Response through Biomechanical Measures.” Journal of Healthcare Engineering 2019 (July): 1614963. https://doi.org/10.1155/2019/1614963.
[5] Moulds, Robert F. W., and Joji Malani. 2003. “Kava: Herbal Panacea or Liver Poison?” The Medical Journal of Australia 178 (9): 451–53. https://doi.org/10.5694/j.1326-5377.2003.tb05289.x
[6] Johnson, A. M. 1999. “Low Levels of Plasma Proteins: Malnutrition or Inflammation?” Clinical Chemistry and Laboratory Medicine: CCLM / FESCC 37 (2): 91–96. https://doi.org/10.1515/CCLM.1999.017
[7] Clough, A. R., S. P. Jacups, Z. Wang, C. B. Burns, R. S. Bailie, S. J. Cairney, A. Collie, T. Guyula, S. P. McDonald, and B. J. Currie. 2003. “Health Effects of Kava Use in an Eastern Arnhem Land Aboriginal Community.” Internal Medicine Journal 33 (8): 336–40. https://doi.org/10.1046/j.1444-0903.2003.00405.x
[8] Hughes, J. T., L. J. Maple-Brown, M. Thomas, P. D. Lawton, A. Sinha, A. Cass, F. Barzi, et al. 2018. “Cross-Sectional Associations of Albuminuria among Aboriginal and Torres Strait Islander Adults: The eGFR Study.” Nephrology 23 (1): 37–45. https://doi.org/10.1111/nep.12956
[9] Martinez-Maldonado, Manuel. 1998. “The Impact of Malnutrition on Kidney Function.” Mineral and Electrolyte Metabolism 24: 20–26
[10] High red blood cell count: Causes & Symptoms. Cleveland Clinic. (n.d.). Retrieved January 31, 2022, from https://my.clevelandclinic.org/health/symptoms/17810-high-red-blood-cell-count
[11] Gleitz, J., A. Beile, P. Wilkens, A. Ameri, and Peters T. 1997. “Gleitz1’ et Al. - 1997 - Antithrombotic Action of the Kava Pyrone ()-Kavain Prepared from Piper Methysticum on Human Platelets.” Planta Medica 63 (1): 27–30. https://doi.org/10.1055/s-2006-957597
[12] U.S. Department of Health and Human Services. (n.d.). Lymphocytopenia. National Heart Lung and Blood Institute. Retrieved January 31, 2022, from https://www.nhlbi.nih.gov/health-topics/lymphocytopenia
[13] Graham, Simon, Rebecca J. Guy, Benjamin Cowie, Handan C. Wand, Basil Donovan, Snehal P. Akre, and James S. Ward. 2013. “Chronic Hepatitis B Prevalence among Aboriginal and Torres Strait Islander Australians since Universal Vaccination: A Systematic Review and Meta-Analysis.” BMC Infectious Diseases 13 (August): 403. https://doi.org/10.1186/1471-2334-13-403
[14] Cadogan, M., & Buttner, R. (2022, January 29). P wave. Life in the Fast Lane • LITFL. Retrieved January 31, 2022, from https://litfl.com/p-wave-ecg-library/
[15] Douglas, Cawte, and Mathews. 1988. “The Effects of Heavy Usage of Kava on Physical Health (Letter to Authors).” The Medical Journal of Australia 149 (6): 341–42. https://doi.org/10.5694/j.1326-5377.1988.tb120654.x
Today we’re going to focus on one study. This study is “Effects of the heavy usage of kava on physical health: summary of a pilot survey in an aboriginal community”. The main author of this study is John D. Mathews. Prof. Mathews works at the Melbourne School of Population and Global Health. He works in the Medicine, Dentistry, and Health Sciences division. His research expertise includes: Epidemiology, biostatistics, mathematical modeling, genetic epidemiology, Aboriginal health, transmissible spongiform encephalopathies, herbicides and cancer, radiation and cancer, and public health policy [1]. He, along with his co-authors, assessed health artifacts seen in 39 individuals in Arnhem Land. It should be understood that the author was simply reporting what they saw, and making the best conclusions with the data they had at the time. In 1988 not much was known about the overall health effects of kava and all we had to draw on was empirical data.
I want to focus on this because through the years this study alone is referenced as proof of liver harm, and various other issues that are more likely related to the population that was studied, than anything to do with kava. The authors themselves specifically acknowledge this fact in a follow up from letters to the author [15].
The Study:
In 1987-1988 39 Kava consumers and 34 non-users were studied in Arnhem Land. Of these current users 20 (27%) were classified as “very heavy users” at 440g/week, 15 (21%) were classified as “heavy users” at 310g/week, and 4 (5%) were classified as occasional users at 100g/week.
Instead of attempting to re-word this, it’s best you just read it word-for-word as it is written.
- Low BMI - Heavy users were found 20% underweight.
- Poor Health (whatever exactly that means)
- Puffy Face
- Scaly Rash
- Increased patellar reflexes.
- Increases in Gamma-glutamyl transferase on liver function tests.
- Albumin, plasma protein, urea, and bilirubin levels were decreased in kava users.
- High density lipoproteins were increased in LFTs (Liver function tests)
- Low density lipoproteins were increased in LFTs
- Haematuria - Blood found in urine.
- Poorly acidified, and low specific gravity urine.
- Increased red-cell volume
- Decreased platelet count
- Decreased lymphocyte count.
- Shortness of breath associated with tall p-waves on resting electrocardiogram.
Let’s address these one at a time.
Low BMI
- This is actually seen across multiple studies of the kava drinking population. Causality is indicated across 4 different studies [2]. Be that as it may, it should be taken into account that Indigenous people frequently suffer greater early mortality rates and poorer health status when compared with non-indigenous people [3].
- This again more likely corresponds to the population being studied than it does to any kava consumption. In Australia, the difference in mortality rates between indigenous and non-indigenous population is among the highest worldwide with life expectancy being 10 years less for Aboriginal and Torres Strait Islander people. Dietary factors contribute to overall disease at over 3 times the rate of non-Indigenous Australians [2]. It would also make sense that low BMI and poor health may go hand in hand in this population, but not be due to any exposure to kava, and more explained by dietary exclusions. Pains in the chest, and shortness of breath are included in this general “Poor health” diagnosis.
- This one is interesting. It’s rare that we see “puffy face” reported as a standard side effect of drinking kava. What we HAVE seen is this occur with drinking alcohol and kava together. It’s likely that the individuals studied had either been drinking alcohol currently at the time, or had been drinking alcohol close in time to when they had been drinking kava. “Puffy face” shows up in 5 specific studies with each reference pointing back to this one Mathews 1988 study.
- This side effect has the highest level of incidence among studies. Causality is indicated here [2]. Based on dose consumed. Higher levels of consumption see this at higher rates.
- Patellar reflexes are observed for neurological tests, making it an essential tool for diagnosis in many neuromuscular diseases [4]. I really don’t know why this was included. I suppose it was looking for instances of stroke. The study goes on to state “the patellar reflexes were more brisk in kava users, whereas reflexes at the ankle were similar to those of non-users”, and “These symptoms variously may reflect anxiety”, and finally “Further research is needed to resolve these matters”.
- At least 6 individual studies have confirmed this rise in GGT among heavy kava drinkers [2]. Ths issue with this is that this study describes this change with the following explanation: “The markedly elevated plasma levels of GGT provide strong circumstantial evidence for a hepatotoxic effect of kava”. It is often stated in these kava papers that this rise in GGT is evidence for “subclinical liver toxicity”. This is incorrect. Drugs which raise GGT levels without corresponding increases in other metrics seldom (if ever) cause acute liver failure or cirrhosis of the liver [5].
- This specific harm is quite egregious in terms of applying it to kava. Reduction in these proteins can be associated with malnutrition, and inflammation as well as a number of other disease states [6]. The aboriginals were shown to have higher natural instances of C-reactive proteins as well as higher amounts of IgE indicating inflammatory conditions which were seen even in the people who weren’t drinking kava [7].
- There are only two studies which correlate this effect to drinking kava. One is Mathews, and the other is Alan Clough. They both study the Aboroginal communities in the Northern Territory which means the results could be confounded by malnutrition issues within the population. With that in mind, current consumers of kava have shown increases in HDL and LDL when drinking kava (Personal Experience).
- This effect is shared by no other research study on kava. There is no evidence of this happening in the average kava drinking population. It is important to keep in mind that a study on 591 Torres Strait Aboriginals found a 41.5% prevalence of albuminuria. Albuminuria is associated with diabetes, obesity, and haematuria [8]. In short, the population itself is the factor, and not the kava consumption.
- Again, this is referenced in kava research nowhere except for this 1988 study. Studies have shown malnourished children and adults have a decreased capacity to excrete an acid load via urine [9].
- This effect has only shown in ONE article, Mathews et al 1988. No reproductions of this effect have been seen in subsequent research. Medical conditions that can cause an increase in red blood cells include: Heart failure, causing low blood oxygen levels. Congenital heart disease (born with it) Polycythemia vera (a blood disorder in which the bone marrow produces too many red blood cells) [10]. It is extremely unlikely for kava to be a cofactor in this effect.
- Only shown in Mathews et al 1988 and Gelitz 1997 study [11]. Subsequent research has shown no statistical change in platelets with kava consumption (see below) [7].
Decreased lymphocyte count.
- Here we again speak about the immune system and the picture painted by the Aboriginal people. Decreased lymphocyte numbers are classically seen as an indicator of chronic infection [12]. Evidence has been seen in this population for various chronic diseases, including hepatitis [13].
- Tall P-waves have been associated with heart issues related to malnutrition and anorexia. The presence of this indicator is usually due to pulmonary hypertension, or chronic respiratory disease [14]. This again likely reflects the health issues experienced by the population, and does not reflect effects caused by the consumption of kava.
With all of that said, it should be obvious now that the study was plagued with confounding factors introduced by the group of people being studied. Mathews himself even backs this up in his response to letters to the authors. He states “At no stage have we suggested that kava is the sole cause of the health problems that were described; in particular, it is likely that malnutrition is an important cofactor [15]”.
[1] Prof John Mathews - University of Melbourne. (n.d.). Retrieved January 31, 2022, from https://findanexpert.unimelb.edu.au/profile/29800-john-mathews
[2] Rychetnik, Lucie, and Christine M. Madronio. 2011. “The Health and Social Effects of Drinking Water-Based Infusions of Kava: A Review of the Evidence.” Drug and Alcohol Review 30 (1): 74–83. https://doi.org/10.1111/j.1465-3362.2010.00184.x
[3] Gwynn, Josephine, Kyra Sim, Tania Searle, Alistair Senior, Amanda Lee, and Julie Brimblecombe. 2018. “Effect of Nutrition Interventions on Diet Related and Health Outcomes of Aboriginal and Torres Strait Islander Australians: A Systematic Review.” BMJ . https://doi.org/bmjopen-2018-025291.
[4] Salazar-Muñoz, Yolocuauhtli, G. Angelina López-Pérez, Blanca E. García-Caballero, Refugio Muñoz-Rios, Luis A. Ruano-Calderón, and Leonardo Trujillo. 2019. “Classification and Assessment of the Patelar Reflex Response through Biomechanical Measures.” Journal of Healthcare Engineering 2019 (July): 1614963. https://doi.org/10.1155/2019/1614963.
[5] Moulds, Robert F. W., and Joji Malani. 2003. “Kava: Herbal Panacea or Liver Poison?” The Medical Journal of Australia 178 (9): 451–53. https://doi.org/10.5694/j.1326-5377.2003.tb05289.x
[6] Johnson, A. M. 1999. “Low Levels of Plasma Proteins: Malnutrition or Inflammation?” Clinical Chemistry and Laboratory Medicine: CCLM / FESCC 37 (2): 91–96. https://doi.org/10.1515/CCLM.1999.017
[7] Clough, A. R., S. P. Jacups, Z. Wang, C. B. Burns, R. S. Bailie, S. J. Cairney, A. Collie, T. Guyula, S. P. McDonald, and B. J. Currie. 2003. “Health Effects of Kava Use in an Eastern Arnhem Land Aboriginal Community.” Internal Medicine Journal 33 (8): 336–40. https://doi.org/10.1046/j.1444-0903.2003.00405.x
[8] Hughes, J. T., L. J. Maple-Brown, M. Thomas, P. D. Lawton, A. Sinha, A. Cass, F. Barzi, et al. 2018. “Cross-Sectional Associations of Albuminuria among Aboriginal and Torres Strait Islander Adults: The eGFR Study.” Nephrology 23 (1): 37–45. https://doi.org/10.1111/nep.12956
[9] Martinez-Maldonado, Manuel. 1998. “The Impact of Malnutrition on Kidney Function.” Mineral and Electrolyte Metabolism 24: 20–26
[10] High red blood cell count: Causes & Symptoms. Cleveland Clinic. (n.d.). Retrieved January 31, 2022, from https://my.clevelandclinic.org/health/symptoms/17810-high-red-blood-cell-count
[11] Gleitz, J., A. Beile, P. Wilkens, A. Ameri, and Peters T. 1997. “Gleitz1’ et Al. - 1997 - Antithrombotic Action of the Kava Pyrone ()-Kavain Prepared from Piper Methysticum on Human Platelets.” Planta Medica 63 (1): 27–30. https://doi.org/10.1055/s-2006-957597
[12] U.S. Department of Health and Human Services. (n.d.). Lymphocytopenia. National Heart Lung and Blood Institute. Retrieved January 31, 2022, from https://www.nhlbi.nih.gov/health-topics/lymphocytopenia
[13] Graham, Simon, Rebecca J. Guy, Benjamin Cowie, Handan C. Wand, Basil Donovan, Snehal P. Akre, and James S. Ward. 2013. “Chronic Hepatitis B Prevalence among Aboriginal and Torres Strait Islander Australians since Universal Vaccination: A Systematic Review and Meta-Analysis.” BMC Infectious Diseases 13 (August): 403. https://doi.org/10.1186/1471-2334-13-403
[14] Cadogan, M., & Buttner, R. (2022, January 29). P wave. Life in the Fast Lane • LITFL. Retrieved January 31, 2022, from https://litfl.com/p-wave-ecg-library/
[15] Douglas, Cawte, and Mathews. 1988. “The Effects of Heavy Usage of Kava on Physical Health (Letter to Authors).” The Medical Journal of Australia 149 (6): 341–42. https://doi.org/10.5694/j.1326-5377.1988.tb120654.x