The food we eat is the greatest cause of death and illness worldwide. The main culprits - salt, sugar and fat - are now so embedded in our diet, in the form of processed foods, that most of us consume far too much.

Yet Professor Graham MacGregor doesn't believe it's up to us to reverse this situation. It's up to the food industry, he says, who manufacture the processed foods, to take the 'rubbish' out.

Now Professor of Cardiovascular Medicine at the Wolfson Institute of Preventative Medicine, Graham MacGregor has spent much of his career campaigning tirelessly to persuade the food industry to do just that - to reduce these demons in our diet - firstly salt, and now sugar.

And he's had remarkable success. As a nation we now eat thirty thousand tonnes less salt each year than we did fifteen years ago, saving the NHS a staggering 1.5 billion per year.

Blood pressure lies at the heart of this huge saving and, as Graham explains to Jim al-Khalili, blood pressure is not a natural consequence of ageing. High blood pressure is simply a consequence of too much salt.

Producer: Beth Eastwood.