Blood pressure - a silent killer

Hypertension - Aimee Wachtel/Holyrood

Having high blood pressure, or hypertension, is a big deal. It is the cause of more death than any other single risk factor in the world, above smoking, malnutrition and infectious diseases and it is the leading contributor to the global burden of disease. 

Like obesity and diabetes, it increases the risk of heart attacks, heart failure and strokes. 

But high blood pressure is more common than obesity or diabetes. In fact, around one in three adults in Scotland, and in the UK, is thought to have the condition, and the number is predicted to rise.

What’s worse, many will not even know they have it. Sometimes hypertension causes symptoms such as headache, shortness of breath, dizziness or nose bleeds, but most people have no symptoms whatsoever. They feel completely healthy, oblivious to the fact they are at major risk of what remains Scotland’s single biggest killer – coronary heart disease. 

No wonder, then, that the World Health Organisation (WHO) branded hypertension ‘the silent killer’. In a 2013 report, WHO said it affects one billion people worldwide, leading to heart attacks and strokes.

As part of its international push to tackle non-infectious diseases, WHO challenged countries to reduce the prevalence of raised blood pressure by 25 per cent by 2025.

But for Scotland to do that, it faces a challenge.     

Not only are around half of us unaware we have it, we do not get our blood pressure taken regularly. Furthermore, when diagnosed, one in four of us does not take the medicines prescribed to bring our BP down.

Could it be simply that Scotland is just not taking the problem seriously enough? 

Professor Rhian M Touyz, director of the Institute of Cardiovascular and Medical Sciences at the University of Glasgow, says it is “mind boggling” that people don’t seem to understand the link with diseases which can leave you “totally incapacitated”. 

Touyz is a British Heart Foundation chair of cardiovascular medicine and president of the International Society of Hypertension.

As well as heart disease, she points out, increased pressure on the arteries can also lead to kidney failure, eye problems, peripheral artery disease and some forms of dementia.

“It’s amazing to think that in the majority of cases it’s preventable,” she tells Holyrood.

“Because if we treat hypertension properly all those morbidities could be reduced. And yet despite the knowledge of all of this, there seems to be a lackadaisical attitude, or at least [it’s] not taken very seriously by the public, and sadly by some GPs.”

The fact hypertensive people can feel healthy is a contributing factor in the problem, she suggests.

“Sometimes, sadly, what we find is the first time someone finds out their blood pressure is high is when they come into emergency having had a stroke,” she says.

“Or they go to the optician to have their eyes checked because they can’t see so well, and there we can see the blood vessels are already injured in the eye.”  

The whole month of May has been dedicated to a worldwide campaign to raise awareness in an attempt to get more people to get their blood pressure taken. This includes a screening programme which aims to take readings from 25m people in one month alone, including 2.5m people in India and 1.7m Filipinos. 

In Scotland, regular screening of blood pressure did form part of the now abandoned ‘Keep Well’ health checks for the over-forties but currently health boards are inconsistent in their approach.

Writing in the medical journal The Lancet, Professor Neil Poulter of University College London said that despite the fact “blood pressure can be measured quickly, cheaply, and painlessly and can be treated cost-effectively… perhaps partly because hypertension usually has no related symptoms and is so common, it receives insufficient attention from the general public, the medical profession, and health policymakers.”

The actual cause of hypertension is unknown, but there are a number of risk factors associated which are well documented. 

Some are outwith our control. As you get older, your blood pressure increases. Men are more likely to get high blood pressure, and women after the menopause. Some ethnic groups are more at risk. 

The genetic component is not as strong as once thought, according to Touyz, “but for sure, if both your parents have got high blood pressure then that can impact on the probability of the child having high blood pressure”.

Most of the risk factors, however, are associated with lifestyle. Poor diet, a lack of exercise, alcohol and smoking are all factors. 

“Ageing will increase the blood pressure. But if you get older and you have a high salt diet and you’re obese and you don’t do exercise and your parents have hypertension then the chances of you having not only hypertension but also a cardiovascular event is much, much higher,” says Touyz.

While smoking rates have come down in Scotland, alcohol and obesity remain a persistent problem. Salt, meanwhile, is often an overlooked factor. 

Research by renal physiologist Matthew Bailey at the University of Edinburgh has confirmed a link between blood pressure and salt intake in mice. Bailey says the human body has struggled to adapt to a shift in diet from a time when salt was a rare commodity.

“Instead of it being a scarce and much prized resource, we’re now living in a society that is saturated and our bodies are not able to cope with this,” he says.

He points to a 1988 study of the Yanomami people in the Amazon basin who live mostly a pre-industrial lifestyle, with a salt intake of around half a gram per day. Their blood pressure is consistently low. 

Despite a WHO guideline to restrict your salt intake to 5gm a day, the UK Government set the recommended daily amount at 6gms a day. On average, people in the UK are eating eight or nine grams a day.

Bailey himself discovered he was eating around 8gms a day, and after spending “three challenging weeks” trying to reduce it, it remained above the regulatory limits. 

“We learned it’s really hard to reduce your salt intake. Why? Because actually, most of our salt intake is not within our control. About 75 per cent of the salt we eat is already in the foods we eat. It’s part of the manufacturing process, in the processed food.”

A frozen pizza often contains around 6gms of salt, while a pre-packaged sandwich will contain a third of your recommended limit. 

“I think people underestimate in terms of salt,” says Touyz, pointing to the high levels in bread and breakfast cereals.

“Anything in a tin or a box or a packet, even frozen vegetables, have got salt in.”

Bailey calls it “the hidden devil in our cupboards” when public health initiatives by industry have been focused elsewhere.

“Salt has not had the same kind of play as sugar, so when healthy food options are marketed, they’ve been marketed around sugars and fats, not necessarily around salts,” he says.

Attempts to reformulate salt in food products have made slow progress, but last year, Food Standards Scotland (FSS) reported a 13 per cent reduction in salt intake in Scotland since 2006. 

This was welcomed, although the Scottish Government maintained the same target – the 6mg a day limit – in its revised dietary goals for Scotland published a month later. Scots still consume 30 per cent more than that, on average.

“We recognise the effort made by the food industry to achieve this through reformulation of their products,” said FSS.

Heather Peace, Head of Nutrition Science Policy at FSS, said: “More remains to be done with two-thirds of adults in Scotland still eating too much salt. 

“We are looking for manufacturers and retailers to further reduce the salt content of their products. This in turn will help to reduce the risk of high blood pressure, heart disease and stroke in the population.

“As well as cutting down on salty foods and adding less salt at home, people in Scotland can make informed choices when shopping by checking food labels and choosing lower salt products. It is also important to choose less salty food when eating out.”

This last one may prove difficult for consumers, with take-away outlets not regulated at the same level supermarkets are. There could easily be as much as 10gms in a portion. 
Bailey suggests there is an inequality issue as well. 

“My view is the burden is disproportionately distributed,” he says. “One of the ways food is driven to people who aren’t so well off is through value meals and ‘essential’ ranges or whatever, and these are the ranges which tend to be high in sugar, high in fat and high in salt.

“I think we’re in a phase where there is more notice taken of salt and things can be changed but the way it’s changing is not evenly distributed across society.”

Facing such odds, isn’t it tempting to fall back on medicine to provide the answers? Faced with a diagnosis, patients will need to be “very, very motivated” to get their blood pressure back down, Rouyz suggests.

“One can do it. There is absolute evidence to show that without taking any drugs and doing the right things in terms of lifestyle modification, blood pressure can be reduced. There’s no question about it,” she says.

“The problem is it isn’t easy. It isn’t easy to tell somebody who is forty, fifty or sixty to change the way they live.”

Usually drug treatments are then needed, but Rouyz says these should be seen as complementary, not an alternative, to lifestyle changes.

“The one thing there is no question about is that the efficacy of the drugs is much better if there are complementary lifestyle modifications. We definitely see that we can use lower doses and we don’t need to use as many different types of drugs if the patient has a healthy lifestyle.”

But while understanding of hypertension and the risk factors has grown, and a recognition that its global prevalence is linked with demographic ageing, rapid urbanisation, and the globalisation of unhealthy lifestyles, the actual cause of the condition remains a mystery.

Unravelling this is what Rouyz has been researching at the University of Edinburgh, backed with funding from the British Heart Foundation.

Her work focuses on blood vessels and how they support every cell in the body.

“If the tubes are not functioning properly, if they become constricted or if they break, or clog up, the blood flow will be impeded and then the tissues and the organs will not be able to receive good nutrition and oxygen. Eventually, the tissues will die, and that’s what happens in a heart attack or a stroke,” she explains.

Damage to the small blood vessels found in the periphery of the body can both be a symptom of high blood pressure and cause it to increase further, she has found. She describes it as a “vicious cycle” where high blood pressure causes vascular injury and that further increases blood pressure.

A chicken and egg scenario? 

“Exactly, and I think whatever is initiating or triggering the whole process is probably quite complicated, and there’s probably quite a few factors involved,” she says.

While research seeks answers to the bigger questions, citizens can also play their part, she suggests.

Reducing alcohol and salt consumption and stopping smoking are a priority, while balancing diet and exercise is also an obvious consideration.

And while people can’t check for a lump like in cancer, they can get their blood pressure tested, and Touyz is keen for there to be more education on the issue. 

“I actually think we need to target the adults through the children. We need to be teaching the children maybe at school so they will then go home and teach their parents. Because it is not easy, as I say, to institute change once one is established in one’s ways. 

“But it is very doable. It does demand some discipline but it can be done.”