“The purpose of life is to contribute in some way to making things better.”
Robert F. Kennedy

We’re often told in one way or another that the actions we take can make a difference – voting in elections, turning the light switch off to save energy. If you’re anything like me, then you’ll have had your doubts about just how true that really is. Will I really affect pollution levels and climate change if I don’t own a car? Will my vote in the election really make any difference?

It’s doubts like these that make me grateful for evidence that shows just how much collective power individuals can have. Evidence like the Million Women Study, which has again been in the news this week following the publication of two new papers in BMC Medicine.

Between 1996 and 2001, over 1.3 million women were recruited to this study, which is being coordinated by researchers at University of Oxford. It seems likely to me that many of those who were asked to sign up may have doubted that their contribution would make a difference, but thankfully that didn’t stop them.

A staggering one in four UK women from the target age group  (50-64 year olds) have participated in the Million Women Study, making it the largest of its kind in the world. The sheer size of the study is allowing researchers to look at changes in the health of a whole population over time.

It started with the primary aim of investigating the link between Hormone Replacement Therapy (HRT) and breast cancer. Previous research had already suggested the link, but the scale of the Million Women Study allowed researchers to study it in a much greater sample size. Some of the earlier findings have dramatically affected HRT prescription patterns and guidelines, by showing that HRT use increases a woman’s risk of developing breast cancer.

Since then, the research has expanded to look at a whole variety of lifestyle factors and their effects on our health, from links between mobile phone use and cancer, to how having children influences body size later in life.

As mentioned, over the last week, two further papers have been published on findings from the study. The first, which featured in The Guardian last Wednesday, looked at the effects of being married or living with a partner on the health of women, and found that while there was no significant difference to the risk of developing heart disease for women with a partner versus those that didn’t have one, those that were in a relationship were less likely to die from the disease.

The second study, published on Saturday and also covered in The Guardian, looked at the effect of being overweight or obese on illness and hospital admission levels. With full height and weight information on 1.2 million of study’s participants, the researchers were able to show that: “All but three of the 25 categories of admission considered showed clear associations with BMI, although the magnitudes, and sometimes the shape, of the associations varied considerably.” In all, it found that one in eight admissions to hospital of women over 50 are due to being overweight or obese.

These results are the latest addition to an ever-growing series of findings from the study, and no doubt there’ll be many more to come. Every one of the women taking part in the Million Women Study is helping researchers to confirm and expand our understanding of the impacts of our lifestyle on our health, and provide strong evidence upon which new policies and initiatives can be created to tackle some of the biggest risk factors for disease. A poignant reminder that one person really can make a big difference.