There is increasing evidence that microbial community structure and diversity are associated with disease severity and clinical outcomes, both in stable chronic obstructive pulmonary disease (COPD) and in exacerbations. New evidence has confirmed that the gut-lung axis – the cross-talk between the gut and the lung – is a bi-directional condition that is a continuous blood communication between the two sits that, in this way, would be able to modulate each other's local immune response and the composition of the respective microbiota. However, although it is clear that the gut microbiota influences inflammation in the peripheral system, what happens in the lung is still poorly understood. As malnutrition is an important factor in COPD, nutritional support might be a strong component of disease management and prevention. In this review, we tried to elucidate the role of diet and dietary supplementation affecting the lung microbiota with respect to stable COPD and exacerbation.