Is having an apple a day really as healthy as they say? According to a new study published in the journalFrontiers in Microbiology, it largely depends on what types of bacteria the apple carries.
Apples are one of the most popular fruits in the world. It represents an excellent source of nutrients: vitamin C, multiple B vitamins, natural antioxidants, and numerous minerals. Apples are also a good source of dietary fiber.
However, as with any other raw food,apples are also a source of microorganisms that enter the intestine and colonize it.Although generally temporary, this exchange of bacteria can have health implications.
Recently, a team of researchers from the University of Technology in Graz (Austria) decided to find out more about the bacteria that are attached to apples. More specifically, they were interested in finding out if there was a noticeable difference between the bacterial populations carried by organic, hand-grown apples and those present in typical store-bought apples.They are often more exposed to chemical fertilizers and pesticides.
The team’s findingsthey highlight the amount of bacteria that a typical apple carries.They also show how the bacterial populations present in organic apples can affect the taste of the fruit and the health of the consumer.
Not all apples are the same
“Bacteria, fungi and viruses in our food transiently colonize our intestines. Cooking kills most of these, making raw fruits and vegetables particularly important sources of gut microbes,” explains study lead author Gabriele. Berg.
However, “although recent studies have mapped the fungal content of apples, less is known about the bacteria in apples,” Berg continues.
The researchers analyzed the bacterial content of the different components of an apple: the stem, the peel, the pulp of the fruit, the seeds and the calyx. They did this for both organic apples and conventional store-bought apples. Then, they compared their findings for the two types of fruit.
The team found that both types of apples had similar numbers of bacteria. “Putting together the averages for each apple component, we estimate that a typical 240g apple contains approximately 100 million bacteria, ” Berg says.
They also found that most of the bacteria were present in the seeds of the apples, and the rest had settled on the pulp.
There were clear differences between the bacterial populations present in organic apples compared to those bought in normal stores.
“ Freshly harvested and organically handled apples harbor a significantly more diverse, uniform and distinct bacterial community, compared to conventional ones,” the expert clarifies.
In apples bought at regular stores, potentially harmful bacteria appeared to be more abundant. In contrast, organic apples appeared to contain a more significant number of healthy bacteria.
“We found Escherichia-Shigella , a group of bacteria that includes known pathogens, in most samples of conventional apples, but not in organic apples. For beneficial Lactobacilli – of probiotic fame – the opposite happened,” says the lead author.
Better, the organic ones
Different bacterial populations may also explain why organic apples may taste better than normal apples, according to Professor Berg: “ Methylobacteria, known to enhance the biosynthesis of strawberry-flavored compounds, was significantly more abundant in organic apples, especially in rind and meat samples, which in general had a more diverse microbiota than the seeds, the stem or the calyx “.
Looking at the current findings, the study authors suggest that researchers should repeat this analysis for other types of fruit to find out if other staples also differ in terms of their bacterial content based on growing methods.
“The microbiome and antioxidant profiles of fresh produce may one day become standard nutritional information, displayed alongside macronutrients, vitamins and minerals to guide consumers,” says Birgit Wasserman, co-author of the paper. “Here, a key step will be to confirm the extent to which diversity in the food microbiome translates into gut microbial diversity and better health outcomes.”
Referencia: Birgit Wassermann et al, An Apple a Day: Which Bacteria Do We Eat With Organic and Conventional Apples?, Frontiers in Microbiology (2019). DOI: 10.3389/fmicb.2019.01629
