The idea that eating 30 different plant foods each week is crucial for a healthy gut microbiome has taken hold in recent months. However, experts argue that this claim may be more marketing hype than scientific fact, and they warn against treating it as a definitive health target. Research published in the journal mSystems in 2018 did suggest a link between eating over 30 plants weekly and a more diverse gut microbiome – which has been associated with lower disease risk.
The original study involved over 10,000 participants from the US, UK, and Australia who provided stool samples and detailed their typical dietary intake. Analysis revealed that those consuming more than 30 distinct plant foods per week generally had a more diverse gut microbiome compared to those eating fewer than 10. While this finding is promising, it's essential to note that the study identified only a correlation between eating 30 plants and improved health outcomes – not a direct causal link.
Dr Daniel M Davis, head of life sciences at Imperial College London, stresses that 30 is not a 'magic number'. He points out that the original study didn't compare groups consuming specific numbers of plants to determine a clear threshold. Moreover, he notes that individuals who eat a wide variety of plant foods are often engaged in other healthy lifestyle practices – such as regular exercise and adequate sleep – which can also influence the gut microbiome.
The commercialisation of this concept is another concern raised by Dr Davis. The '30 plants a week' message has spawned a lucrative market for expensive dietary supplements claiming to aid in reaching this target. However, there is currently little independent evidence supporting their effectiveness. While a varied diet rich in fruits, vegetables, legumes, nuts, and wholegrains undoubtedly benefits overall health, the specific goal of 30 plants per week remains unproven.
As Dr Davis warns consumers to be wary of these commercial claims, it's essential to focus on what we do know: a balanced diet with plenty of plant-based foods is beneficial for our overall health. Rather than fixating on an arbitrary target, we should aim to make informed choices about our eating habits based on the best available evidence.