Lacto-Fermented Foods Linked to Esophageal Cancer

Lacto-Fermented Foods Linked to Esophageal Cancer

Did our ancestors have wisdom that we can recover to help us with our modern health problems? Both the Weston A. Price Foundation and the promoters of Paleolithic diets claim this is the case. They suggest that the deficit of lacto-fermented foods in the modern Western diet deprives us of beneficial gut bacteria thus making us susceptible to viruses and other illnesses. The reasoning is not only intriguing, but very appealing. What does science say about lacto-fermented foods?

Reviewing the Research

2009 meta-analysis examined 34 English and Chinese language studies conducted to examine the connection between lacto-fermented foods and cancer of the esophagus. After reviewing the evidence, the researchers determined that there was double the risk of esophageal squamous cell carcinoma associated with eating lacto-fermented foods.

Asia is one of the areas of the world where lacto-fermentation, also called “pickling,” has been practiced for centuries and where that ancient practice continues today. In China during the 1960s, cancer registries began to be kept which showed an unusually high incidence of esophageal cancer in certain provinces. Even after controlling for smoking and alcohol, the cancer rate was significantly high. Scientists began studying the common use of foods preserved by this method as the cause for the elevated cancer statistics. In these areas of China, families eat pickled foods daily for 9-12 months out of the year. For some families, these foods form an integral part of the diet.

The Pickling Process 
Chinese pickled vegetables are generally made by tightly packing salted vegetables into a jar, allowing them to ferment, and storing them for weeks or months. This process is named for the Lactobacillus strain of bacteria which was first studied in fermented milk. These bacteria convert lactose or other sugars into lactic acid, although lacto-fermentation does not require the use of dairy products. This preservation process relies on fermentation along with the growth of fungi and yeasts and can potentially produce carcinogenic N-nitroso compounds and mycotoxins. It has also been shown in some studies to produce pickles that have mutagenic and carcinogenic microorganisms. In 1993, the World Health Organization added Asian-style pickles to its list of possible carcinogens. 

Traditional Diets Value Fruits and Vegetables
So, do traditional people groups have wisdom we need to reclaim? Absolutely! But in looking at how they processed food in bygone eras, maybe we’ve missed the obvious. What were they preserving? Fruits and vegetables! When people live without refrigeration, they do what they can to ensure adequate nutrition for the months when fresh foods aren't available. That is not the current condition in the Western world where we benefit from refrigeration. Although we enjoy access to fresh produce year round, we often suffer with health problems because we choose to eat a diet rich in meat, eggs, dairy products, and processed foods--a diet very different from the foods eaten by the average person centuries ago.

Dr. John McDougall points out that our modern diet resembles the indulgent diet of ancient royalty, and we suffer from the same diseases ancient royalty died from. The majority of the populace from centuries past thrived on a diet that was based on vegetables, legumes, fruit, and grains--not based on animal products. Today, when we adopt a diet resembling the foods that have preserved civilizations for centuries, we too can enjoy improved health. A low fat, whole-foods plant-based diet without added oil has been shown to prevent, stop, and often reverse diseases like obesity, cardiovascular disease, diabetes, hypertension, arthritis, and cancer--all without the risks posed by pickling our foods.

Do you have science to share regarding lacto-fermented foods?
Join the discussion at our discussion forum to share your views.

Since this blog first posted, we have received the following helpful links from our readers:

(1) How Sauerkraut Gives You Stomach Cancer (Fermented and Pickled Foods)

(2) Fermented Foods: Intake and Implications for Cancer Risk

Here is additional research on the link between lacto-fermenting and cancer:

(1) Fresh and pickled vegetable consumption and gastric cancer in Japanese and Korean populations: a meta-analysis of observational studies.  

(2) Pickled food and risk of gastric cancer--a systemic review and meta-analysis of English and Chinese literature.

(3) Vegetables, but not pickled vegetables, are negatively associated with the risk of breast cancer. 

For further information, you might like to read:

(1) Phytic Acid in Grains? No Problem!

(2) The Paleo Diet is Uncivilized

(3) Dr. Michael Greger Reviews the Paleo Diet

(4) Gladiators were Vegan

(5) Is Kimchi Good for You?

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Comments (9)

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  1. Jill, The Veggie Queen

I am a bit confused by this. Are you suggesting that people avoid fermented foods? Or are you suggesting that people eat more fruits and vegetables fresh? Or both.

I eat fermented foods and since I don't live in China and don't eat what they eat, I am not concerned. Should I be? I eat lots of fresh fruits and vegetables.
I have my doubts about the direct link between eating fermented foods as many here in the US do and esophageal cancer. Was there a study beyond just looking at what was reported in the review?

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Hello Jill,
It is a great honor to have you commenting on our site. Thank you very much for gracing us with your presence. We appreciate your work very much!
We understand this is a topic with a lot of considerations. The study we have highlighted was specifically about Lacto-Fermented Foods.
The bottom line, is that there probably is not yet a bottom line. We are seeing studies reporting benefits and dangers of fermented foods. The confusion is also compounded by the fact that there are many ways to ferment foods. Again, the report we wrote about is for Lacto-Fermented Foods.
We do not yet have a clear answer from science for every type of food fermentation although we are starting to uncover quite a few studies which we need to digest (excuse the pun).
Since we published this and posted it to social media we have received quite a few resources sent in to us from other readers. Some of the most recent ones have been added to the bottom of this blog post. We are focusing only on the studies about Lacto-Fermented Foods for this blog. Obviously we need to put together more thorough research regarding other types of fermented foods.
Once again, Thank you for your questions....

Hello Jill,
It is a great honor to have you commenting on our site. Thank you very much for gracing us with your presence. We appreciate your work very much!
We understand this is a topic with a lot of considerations. The study we have highlighted was specifically about Lacto-Fermented Foods.
The bottom line, is that there probably is not yet a bottom line. We are seeing studies reporting benefits and dangers of fermented foods. The confusion is also compounded by the fact that there are many ways to ferment foods. Again, the report we wrote about is for Lacto-Fermented Foods.
We do not yet have a clear answer from science for every type of food fermentation although we are starting to uncover quite a few studies which we need to digest (excuse the pun).
Since we published this and posted it to social media we have received quite a few resources sent in to us from other readers. Some of the most recent ones have been added to the bottom of this blog post. We are focusing only on the studies about Lacto-Fermented Foods for this blog. Obviously we need to put together more thorough research regarding other types of fermented foods.
Once again, Thank you for your questions. They are helping us to delve deeper into the subject.
Sean Carney

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  1. Sean Carney

This was a subject that surprised us by the amount of interest there was on the topic and the amount of responses we received on social media sites. We try to focus primarily on helping people to realize the harmful effects of Meat, Oil, Dairy, Eggs, Refining and Narcotic substances (See our MODERN acronym) and not focus so much on condiments that might have less than stellar ingredients in them.
We do keep running into studies on this subject though and so for people that might be interested we are classifying the studies together in our Starch-Smart Science section until these URLs:
Studies Classified Under Fermented Foods
Studies Tagged Under Pickled Vegetables

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  Comment was last edited about 1 year ago by Sean Carney Sean Carney
  1. Sean Carney    Colin Yardley

Thank you Colin for your reply. It seems to us that everybody agrees that fruits and vegetables are super foods to maintain a more alkaline PH and that whole grains and some nuts and seed are also good as are beans and other legumes. The links you provided seem mostly to be promoting fermented foods and in particular some products. We are a bit suspect about this. It seems that there is still a lot to be learned about the benefits and the detriments of fermented foods.

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  1. BlogGuru
  1.   London, UK...

I like to educate myself as much as possible so I am constantly researching for new discoveries and this is something that changes my view about the lacto-fermented foods. Could it be that something else is triggering the elevated numbers of cancer in Asia?

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  1. Sean Carney    BlogGuru

Hello BlogGuru,
We do not really have all the answers. And, the subject of fermented foods is complicated because of the various ways in which foods can be fermented. Overall most of the research seems to promote fermented foods. But, we are keeping our eyes open for research like this which might show another darker side of some of the fermentation processes. We need to keep our eyes open for other compelling scientific studies as they become available.

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  1. MIKE

so is it the fungi & yeasts that cause cancer, & if so, can foods b fermented w/out them & only the lactobacillus bacteria?

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  1. Linda Carney MD

Hi Mike,

Foods that were fermented using lactobacillus are cited in the study above as being correlated with higher rates of cancer.

Some members of the fungus family have been scientifically shown to have cancer-protective properties. So I don't think we can blame on on the yeasts or fungi, but on the process of fermentation itself.

Since many yeast spores float invisibly in the air, fermenting without contamination by members of the fungal family require rigorous attention to method, which would cut into profits for the food industry. Not likely to be the manner in which fermentation is conducted.

Thanks for writing your comments on our site.
Dr. Carney

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