Kombucha: is a cup of tea good for you?

Abstract

A 54-year-old asthmatic woman presented to hospital with a 10-day history of breathlessness. On examination, she was tachypnoeic with mild wheeze. She had preserved peak flows and was saturating at 100% on room air. Investigations revealed severe metabolic lactic acidosis. On further questioning, it transpired that she drank kombucha tea, which has been linked to lactic acidosis. She made a full recovery with supportive management and cessation of the tea.

Background

Herbal remedies and teas are often neglected from a patient’s history taking. However, they are becoming increasingly popular and little is known about their potential side effects. Herbal tea sales in the UK have increased from £28 million in 2012 to £76 million according to Mintel, market research group.¹ This case highlights a potential risk of kombucha tea and reminds us to ask about herbal remedies in our initial assessment of a patient.

Case presentation

A 54-year-old woman presented with breathlessness and tachypnoea. She had a background of mild asthma, with no previous hospital attendances and was only prescribed inhaled salbutamol as required. She had been feeling out of breath for 10 days, and her symptoms had failed to improve with a week of steroids and doxycycline in the community. Physical examination revealed a respiratory rate of 40/min, oxygen saturation of 100% on room air and a mild wheeze on auscultation of her chest. She had a reasonable peak expiratory flow of 340 L/min, with her best being 400 L/min. She was given two salbutamol 5 mg nebulisers in accident and emergency with no improvement in her respiratory rate. There were no signs to suggest venous thromboembolism. She was an ex-smoker with 10 pack-years' history. There was no history of alcohol excess or illicit drug use. She worked in the National Health Service with no significant occupational exposures. She had consumed kombucha tea daily for several months. There was no history of any other herbal or over-the-counter remedies.

Investigations

Venous blood gases revealed compensated metabolic acidosis with a raised anion gap. The arterial blood gas showed pH 7.45, arterial oxygen tension 16.0 kPA, arterial carbon dioxide tension 1.94 kPA, HCO₃ 10.2 mmol/L, lactate 14.0 mmol/L and base excess −11.8 mmol/L. Ethyl glycol was not detectable. Anion gap was 19.8 mmol/L. This was in the context of normal renal function, liver function and inflammatory markers. C reactive protein was 1.8 mg/L, and viral throat swab was negative for respiratory viruses. Creatine kinase was normal at 32 IU/L and serum glucose was 5.4 mmol/L. There was no consolidation on her chest X-ray, and she had a normal CT pulmonary angiogram as part of her investigations.

Treatment

She was given intravenous fluids overnight, along with standard treatment for a mild exacerbation of asthma, with steroids and inhalers. Over the course of 18 hours, her lactate normalised and her respiratory rate returned to normal. She was discharged home with the advice to cease consumption of kombucha tea.

Outcome and follow-up

She improved with intravenous hydration, and at outpatient follow-up had remained well with a normal lactate level. On admission, her lactic acidosis seemed out of context with her clinical picture as there was no evidence of tissue hypoxia or sepsis. Beta 2 agonists are known to induce lactic acidosis²; however, she had nebulised only a relatively small dose (10 mg) of salbutamol which would not usually be associated with a lactate of 14 mmol/L. In addition, her symptoms of tachypnoea due to metabolic acidosis predated the administration of the nebulised salbutamol by many days. On later questioning, it was discovered that she regularly drank kombucha tea and no other cause for her acidosis was found.

Discussion

Kombucha tea is an increasingly popular health beverage, sold for its purported health properties to prevent cancer, relieve arthritis, prevent memory loss, treat insomnia and stimulate the immune system.³ It is a fermented sugar tea using a ‘symbiotic colony of bacteria and yeast’. This woman fermented her own tea at home using the same kombucha culture for many months, but various bottled preparations are also sold.

There is a paucity of scientific data on the benefits of kombucha tea and associated side effects.^{4 5} However, there are a few case reports of serious, and in some instances, fatal, hepatic dysfunction and lactic acidosis, within close proximity to kombucha tea ingestion. These include two women in Iowa in 1995 who were admitted to hospital with fatal unexplained severe metabolic acidosis⁶ following consumption of kombucha tea and a 22-year-old man with HIV, who developed acute renal failure and lactic acidosis rapidly after ingesting the tea.⁷ The mechanism by which kombucha tea is associated with these adverse effects is unclear, and the microbial composition of the culture, storage conditions, chemical composition of the tea and host factors may all contribute.^{5 8}

To date to our knowledge, lactic acidosis associated with kombucha tea ingestion has not been reported in the UK, and in this case renal and liver function remained normal and the patient fully recovered with supportive measures.

Learning points.

• To remember to ask about herbal remedies during initial evaluation.

• Kombucha tea has several case reports linking it with lactic acidosis.

• There is no proven health benefit of kombucha tea, and further study is needed to establish its safety.