Over the last four decades, the influence of the diet on our health has become better understood. We now have a picture of how nutrition affects infancy, adulthood , and even old age. Paralleling this increase in knowledge, however, has been the realization that foods are not produced equally and a risk exists for infection. In Canada and the United States the safety of food has become a priority and they remain vigilant to stay on top of any potential microbial threat.
There's no wonder that germs and food are considered to be as incompatible as oil and water.
One of the most problematic sources of trouble has been fresh produce. Unlike meats and other processed foods, which can be made safe through cooking, most fruits and vegetables are eaten in their natural raw state. The germs that happen to be on them are ingested with every bite and then make their way through the gut. Most of the times, there is little impact but in the cases where a pathogen might be lurking, the results can be disastrous.
In the last few years alone, there have been widespread outbreaks of infection due to the consumption of a number of fresh vegetables and fruits including lettuce, spinach, tomatoes, cantaloupes, and mangoes. What's worse is that this list is probably not as extensive as it should be; most foodborne infections are not reported and as a result go unnoticed.
However, there is a different perspective on germs and fresh produce that has been under the radar. From a collection of studies looking at the link between diet and the human microbiome there appears to be a benefit to eating raw produce -- a healthier and happier gut. The healthiest microbial populations come from individuals who eat a significant amount of vegetables and fruit.
Those who consistently eat high fat and sugar diets have higher numbers of bacteria known to cause inflammation and other downstream problems including obesity, diabetes, and other chronic diseases. The evidence is fairly clear that eating fruits and vegetables -- when safe -- lead to better overall health.
But until recently, there had been a question lingering about the actual source of the good bacteria. Were they normally in the gut and simply given a better opportunity to grow thanks to the nutrients coming from these natural foods? Or were the foods themselves acting as a source of these good germs?
The answer came earlier this week when Drs. Jonathan Leff and Noah Firer at the University of Colorado, Boulder, published a research article summarizing their work on determining the nature of bacteria on fruits and vegetables. They took eleven different fruit and vegetable products, including those known to be associated with outbreaks such as lettuce, spinach and tomatoes and identified the various bacteria on each. To make the findings even more interesting, they chose both conventionally grown as well as organically grown samples.
The results, while extensive and complex, revealed that the resident bacteria on these foods were for the most part the same as those found in the healthiest microbiomes. They also found that there was a difference between the conventional and organic farming methods -- although the differences were not as most organic farming supporters might expect. While there was a 64 per cent reduction in the number of potentially pathogenic bacteria known as Enterobacteriaceae there were fewer difference amongst other bacterial families.
This difference could provide support for organic farming as a means to minimize the risk of consumer infection. This has already been shown in animals where a shift to organic could lead to a reduction in potential pathogens and antibiotic resistance. However, these extrapolations need to be proven before they can be adopted.
There can be little doubt that we should be aware of the risks that come with eating fresh fruits and vegetables as there appears to be no end to the outbreaks associated with them. However, the majority of these products are safe and there is no reason to eschew them out of fear of infection.
The human diet requires them to keep the body healthy and now it is clear that the gut needs them to keep the microbiome happy. While this may still not be enough to convince former President George H.W. Bush to eat his broccoli, hopefully it will help others to take a little more time in the produce section or for those looking at a locavore lifestyle, the local farmers market.