That's the green line going down. The less nitric oxide, the stiffer the arteries. Your heart makes up for it by working harder. The pressure rises. That's the red line going up.
And that's not the end of it. This is where salt does come in – just not in the way you were told. Salt, processed fats and preservatives – takeaways and ready meals are full of them – irritate the endothelium day after day. Over the years, the smooth inner wall turns rough.
And cholesterol sticks to a rough wall. On top of it, calcium builds up – the same mineral that keeps your bones strong. It has no business in your artery wall. That's where the phrase 'hardening of the arteries' comes from.
Doctors call this mix of cholesterol and calcium 'plaque'. With every layer, the artery wall gets thicker and harder and the space inside narrower – less blood gets through, and it takes more effort to push it along.
Less nitric oxide and more plaque feed off each other. Both end up in the same place – stiff, narrow arteries that your heart has to pump against, day in, day out.