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The Foods We Eat Contain Live Microbes

Credit: Wikipedia

Every month there is more evidence of the importance of the human microbiome or microbiota - the community of microbes that live in and on us. Trillions of microbes! When we eat food, we eat all the microbes that are in the food, and this has effects on the microbes living in the gut (intestines).

How many microbes do we eat daily? An interesting study was published in 2014 that tried to answer this question. The researchers found that the average American adult ingests between 1 million to over 1 billion microbes every day! It depended on food choices.

Another study just published looked at more than 9000 foods in the US health and dietary database (from 74,466 persons). The researchers estimated the number of live microbes present in all the foods. From that they estimated that the intakes of foods with live microbes were pretty low (about 85 grams/day for children and 127 grams/day for adults). Their results were similar to the earlier 2014 study mentioned above.

They found that around 20% of children and 26% of adults consumed foods with high levels of live microorganisms in their diet. Also, American children and adults have steadily increased their consumption of foods with live microbes over an 18 year period of time - but it still didn't meet guidelines.

The researchers found that fruits, vegetables, and fermented dairy foods were the main sources of microbes, as well as 3 important nutrients which Americans generally do not get enough of: calcium, fiber, and potassium. They also mention that fruits and vegetables have more diverse microbes than fermented dairy foods (yogurts have mainly lactic acid bacteria).

Bottom line: Eating a diet rich in fruits, vegetables, and live fermented foods (e.g., yogurt, kefir, fermented pickles, and kimchi) are good ways to increase the number and variety of microbes in your diet. This study did not mention organic foods, but some studies have found more beneficial bacteria in organic produce (e.g., apples).

From Medical Xpress: Quantifying the live microbes on your plate

Many have hypothesized that bacteria and other "friendly" live microorganisms consumed through the diet can play an important role in health. Reduction in dietary microbe consumption has likely contributed to an "impoverished" gut microbiota, which may lead to improper immune system development and an increase in chronic diseases, among other negative health outcomes.

But one of the first steps toward understanding the role of dietary microbes in health is to quantify the number of live microorganisms we consume today in our diets... To create the estimate, the scientists turned to a well-established US health and dietary database, the National Health and Nutrition Examination Survey (NHANES). While this database contains extensive information on the foods consumed by Americans daily, it lacks information on how many live microbes those foods contain.

As a first step, food science and fermentation experts assigned each food in the database an estimated range of live microbes per gram, creating categories of foods with low, medium and high levels of live microbes. The foods in the "high" category (more than 107 colony-forming units per gram, or cfu/g) were primarily fermented dairy foods such as yogurt, fermented pickles or kimchi. Fresh, uncooked fruits and vegetables were also good sources of live microorganisms, represented in the "medium" category (104 to 107 cfu/g).

Using the NHANES data from 2001 to 2018 for nearly 75,000 children and adults, the scientists found that around 20% of children and 26% of adults consumed foods with high levels of live microorganisms in their diet. Both children and adults increased their consumption of these foods over the 18-year study period.

According to co-author Prof. Colin Hill, APC Microbiome Ireland, University of College Cork, "There is no doubt that the microbes we eat affect our health. When we think of microbes in our food, we often think of either foodborne pathogens that cause disease or probiotics that provide a documented health benefit. But it's important to also explore dietary microbes that we consume in fermented and uncooked foods. It is very timely to estimate the daily intake of microbes by individuals in modern society as a first step towards a scientific evaluation of the importance of dietary microbes in human health and well-being."

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