Walking 7,000 steps a day can be enough to boost your brainpower and help protect against a range of different diseases, a major study suggests.

It may be a more realistic target than 10,000 steps, which is often seen as the benchmark to reach.

The research, published in the Lancet Public Health, found that the figure was linked with a reduced risk of serious health issues, including cancer, dementia and heart disease.

The findings could encourage more people to track their steps as a practical way to improve their health, the researchers say.

"We have this perception we should be doing 10,000 steps a day," says lead author Dr Melody Ding, "but it's not evidence-based".

The figure of 10,000 steps can be traced back to a 1960s marketing campaign in Japan. In the run-up to the 1964 Tokyo Olympics, a brand of pedometer was launched called the manpo-kei, which translates as "10,000-step meter".

Dr Ding says this figure was "taken out of context" and became an unofficial guideline, which many fitness trackers and apps continue to recommend.

The Lancet study analysed previous research and data on the health and activity of more than 160,000 adults around the world.

Compared with those who walked 2,000 steps a day, it found that 7,000 steps was linked to reduced risk of:

• cardiovascular disease - down 25%
• cancer - down 6%
• dementia - down 38%
• and depression - down 22%

However, the researchers say some figures could be less accurate than others as they are drawn from only a small number of studies.

Overall, their review suggests even modest step counts of around 4,000 steps a day are linked to better health compared to very low activity of just 2,000 steps a day.

For most health conditions, the benefits tended to level off beyond 7,000 steps, although there were additional advantages to walking further for the heart.

Most exercise guidelines focus on time spent doing physical activity over step counts.

For example, the World Health Organization says adults should do at least 150 minutes of moderate aerobic activity or 75 minutes of vigorous aerobic activity every week.

Dr Ding says this advice can sometimes be difficult for people to understand but the current guidelines still serve an important purpose.

"There are people who swim, cycle, or have physical disabilities that don't allow them to take steps," she explains.

But she says a recommendation on the number of steps people should take could be included as an "addition" that would "prompt people to think about spreading their physical activities throughout the day".

Dr Daniel Bailey, a sedentary behaviour and health expert from Brunel University London, says the study challenges the "myth" that 10,000 steps a day is necessary.

While 10,000 steps is a suitable goal for those who are more active, he says aiming for 5,000 to 7,000 could be a "more realistic and achievable target" for others.

Dr Andrew Scott, senior lecturer in clinical exercise physiology at the University of Portsmouth, agrees the exact number isn't important.

He says "more is always better" and people shouldn't worry too much about hitting a specific target, especially on days when activity is limited.