The human body is sometimes said to host 'two' brains – the big one in your skull and the mini version in your gut . The bridge between th e two is known as the gut-brain connection , and in recent years, this two-way street has emerged as a promising avenue to slow cognitive decline that often occurs as we age. A recent review of 15 human studies, published between 2012 and 2025, has now laid out some of the strongest trials to date on the subject. Even combined, the results are preliminary,