Is kombucha safe to drink in pregnancy?

I get asked this question all the time. However, there is no short answer and very little research on this controversial topic, so I hope this blog post can give you the information you need to make an informed decision.

What is kombucha?

Kombucha has been around for centuries, thought to have originated in China. It is a fermented tea, made with black, white or green tea, sugar, yeast and bacteria. The yeast and bacteria form a culture, known as SCOBY (Symbiotic Culture of Bacteria and Yeast). The sugar is required to 'feed' the bacteria and yeast, which is how the tea ferments (leaving only a small amount of residual sugar in the end product). This process produces organic acids, B vitamins, amino acids and other bio-active compounds.

What are the (potential) benefits?

Kombucha has some extravagant claims - from curing cancer to aiding digestion, improving immunity and healing the gut. Most of these claims are clever marketing without sound scientific evidence. Studies on the role of kombucha in human health are very limited (especially in the pregnant population).

However, the components within kombucha have some potential benefits.

ANTIOXIDANTS

Kombucha contains antioxidants from the tea. Kombucha made from green tea appears to have greater antioxidant effects due to the many bioactive compounds found in green tea. Some studies show that kombucha tea has higher antioxidant activity than un-fermented tea, however other studies show that the levels don't change.

PROBIOTICS

Kombucha contains several species of bacteria, some of which are known probiotics (Lactobacillus and Bifidobacterium). Probiotic yeasts that are common in kombucha include S. boulardii and S. cerevisiae. However the microbiological composition of kombucha is quite complex and more research is needed in order to fully understand its behaviour. Each batch of kombucha will have a slightly different mix of microorganisms, dependent on the quality of the SCOBY, the temperature, the tea to sugar ratio and the fermentation time. It's impossible to know the exact composition unless a sample goes under a microscope.

ANTIBACTERIAL

Kombucha may exert antibacterial activity due to the production of organic acids (particularly acetic acid), large proteins and catechins. These may have an inhibitory effect on harmful microorganisms.

PREGNANCY SPECIFIC "BENEFITS"

Purely anecdotal evidence here, but many women claim that kombucha helps to ease nausea (especially ginger flavoured) and improve fatigue. It offers women something to drink other than water to meet fluid requirements, and it can make women feel more 'social' at gatherings.

What are the concerns?

People are warned against kombucha consumption in pregnancy due to the small amount of alcohol, caffeine and sugar it may contain, and due to the chance of contamination with harmful bacteria. Batches change vastly between manufactures and home brews, therefore the level of these constituents change. Most significantly, there is very limited research on the effects of kombucha in pregnancy as it is unethical to conduct such studies.

However, that's not to say that all kombucha is high risk. Let's learn a little more.

ALCOHOL

All kombucha naturally contains a small amount of alcohol as a result of fermentation. Commercial kombucha sold as a non-alcoholic drink in Australia must be tested at less than 0.5% ABV as per national standards. However some home brews could get as high as 3%.

To give you some perspective, standard beer is ~4% and wine is ~11%. Although the amount in kombucha is minimal, large volumes are not recommended.

CAFFEINE

The caffeine in kombucha obviously comes from the tea. 1 cup of kombucha contains around 10-25mg of caffeine, compared to around 100mg in a standard cup of tea. As you can see this is quite minimal and well below the recommended 200mg caffeine/day for pregnant women.

Some manufactures will add additional caffeine, so check the label.

SUGAR

Sugar is used to make kombucha, however most of it is 'eaten' by the bacteria and yeast during fermentation, so little is left in the end product. However, some manufacturers will add refined sugar or artificial sweeteners to the final brew, so make sure you check the label.

CONTAMINATION

Like all ferments, there is a chance that harmful bacteria could be introduced in the process. This is more likely to happen to inexperienced home brewers.

Commercial kombucha manufacturers adhere to strict sterilisation, sanitation and brewing practices to eliminate the risk of contaminating brews with bad bacteria.

Additionally, some companies use heat or chemicals to kill ALL bacteria. Although these varieties are generally safe to consume during pregnancy, please note that you won’t be getting any beneficial probiotics from these drinks (as the probiotics will be killed).

Take home messages

Like all things in pregnancy, it comes down to using your common sense, weighing up the risk vs benefit, buying from reputable establishments and adhering to proper storage practices.

If you have been brewing and/or drinking kombucha for years, chances are you can continue to drink it without any problems. However it may be worth checking the alcohol and caffeine content of your homebrew and drinking it in moderation (1-2 cups/day).

When choosing a commercial kombucha, it must be raw and unpasteurised to reap the health benefits. This generally means it will need to be refrigerated, so look for kombucha in the cold section of your grocer. You must then keep the kombucha cold (ie. store it in your fridge), otherwise it will continue to ferment and the alcohol level may increase. Also, choose commercial kombucha that doesn't contain a heap of added sugar or artificial sweeteners.

Lastly, if you already eat a diet high in antioxidants, probiotics and prebiotics then there is no need to 'add' kombucha to your diet. You can get similar benefits from drinking normal tea, eating fermented foods (natural yoghurt, kefir, sauerkraut) and eating lots of fresh fruit and vegetables. If you want something bubbly, have sparkling water and infuse it with lemon slices or mint.

Written by Renee Jennings

Photo by Klara Avsenik on Unsplash

References:

1. Marsh AJ, O'Sullivan O, Hill C, Ross RP, Cotter PD. Sequence-based analysis of the bacterial and fungal compositions of multiple kombucha (tea fungus) samples. Food Microbiol. 2014 Apr;38:171-8. doi: 10.1016/j.fm.2013.09.003. Epub 2013 Sep 25. PMID: 24290641.

2. Sreeramulu, G., Zhu, Y. and Knol, W., 2000. Kombucha fermentation and its antimicrobial activity. Journal of Agricultural and Food Chemistry, 48(6), pp.2589-2594.

3. Villarreal‐Soto, S.A., Beaufort, S., Bouajila, J., Souchard, J.P. and Taillandier, P., 2018. Understanding kombucha tea fermentation: a review. Journal of food science, 83(3), pp.580-588.

4. Kozyrovska, N.O., Reva, O.M., Goginyan, V.B. and De Vera, J.P., 2012. Kombucha microbiome as a probiotic: a view from the perspective of post-genomics and synthetic ecology. Вiopolymers and Cell.