Which is the best way to manage blood pressure?

May 24, 2016  19:24

What rises when you eat sugar, but drops at night and when you drink cherry juice? According to new research published this month, it’s your blood pressure.

And last week it emerged that there could be a new enemy for our blood pressure: potatoes.

Researchers at Harvard University found that people who tucked into potatoes four times a week had an 11 per cent increased risk of high blood pressure, compared with those who ate them less than once a month.

It’s thought the high starch levels in potatoes lead to a rise in blood sugar, which may contribute to high blood pressure in the long term. 

Meanwhile, a University of Oxford study found high blood pressure in your 30s or 40s is a warning sign of dementia in later life. It increases by 62 per cent the chance of vascular dementia, the most common type after Alzheimer’s, researchers said.

As many as a third of people in Britain have dangerously high blood pressure, yet few realise they’re at risk. Here we look at things you need to know about the condition. 

EXPERTS SAY ONE ARM ISN'T ENOUGH

Many new theories are emerging about blood pressure — not least how it should be measured.

There are two figures given: the upper number, the systolic blood pressure, shows the pressure in your blood vessels as the heart contracts. The lower number, the diastolic pressure, measures how low your pressure falls as your heart relaxes between beats.

Traditionally, a reading has been taken by checking the pressure in one arm. However, researchers now say doctors should routinely take it in both — if it’s higher in one than the other, this can be an early warning of heart disease, as it suggests there are blockages in parts of the circulatory system.

A study this year from the University of Exeter suggested people who have a difference of more than five points in their systolic blood pressure (the top number) between each arm had nearly double the risk of dying from heart disease in the next eight years.

‘An inter-arm difference in blood pressure is more common in people with signs of blood vessel disease,’ says Chris Clark, the study’s author and a clinical senior lecturer in general practice at the University of Exeter.

Double arm testing is already suggested as the gold standard when someone has high blood pressure, but it’s not always done.

OPTICIANS SPOT EARLY WARNINGS 

Your optician can spot high blood pressure just by looking into the back of your eye.

‘The eye is the only place in the body where you can directly look at the blood vessels without surgery. You can spot a few conditions, one of which is high blood pressure,’ says Dr Nigel Best, an optometrist with Specsavers. ‘It changes the way the blood vessels look.’

HOLIDAYS CAN BE BAD NEWS

Blood pressure varies by the season — it goes up in cold weather and falls when it’s hot.

There are many reasons for this, says Professor Padmanabhan. In hot weather, blood vessels dilate to cool us, which lowers blood pressure; in the cold, the vessels constrict, which sends blood pressure upwards.

When we’re cold we also release more adrenaline to help warm us up, which increases blood pressure.

Most of the time in Britain the seasonal variation won’t make much difference, but when people on blood pressure drugs go somewhere very hot, some can find their blood pressure falls too low and they start to feel dizzy.

It’s most likely to happen if you’re taking multiple drugs, are on diuretics or are elderly. However, you shouldn’t stop taking your medication — ask your GP for advice when you get back.

YOU MIGHT NEED THREE DIFFERENT PILLS 

IF you are prescribed medication for high blood pressure, there’s a good chance you might end up taking more than one.

‘This doesn’t mean the medicines aren’t working, but each type of blood pressure medication can only reduce systolic pressure by a maximum of eight points,’ says Professor Padmanabhan. ‘So, if you have a measurement of 150 and need to lower that to 130, you will need three drugs to do it.’

IS SUGAR AS BAD AS SALT?

Some experts believe sugar might play a bigger role in raising blood pressure than salt.

‘A number of trials showed that a diet high in sugar significantly raised blood pressure in just a few weeks — by about twice what you might see from a high salt intake,’ says Dr James DiNicolantonio, a cardiovascular research scientist who analysed the sugar/salt connection at St Luke’s Mid America Heart Institute in Missouri.

It’s thought this is because sugar makes us more sensitive to the blood pressure-raising effects of salt, making our bodies retain more.

Dr DiNicolantonio suggests limiting levels of processed sugar from foods such as table sugar, honey and agave. Fruit is unlikely to have the same negative effect.

HIGH LEVELS MAY NOT BE ALL BAD 

Research last year found that people who carry genes that increase their risk of high blood pressure had a lower risk of Alzheimer’s disease. 

Biologist Professor John Kauwe, who conducted the trial at the Brigham Young University in the U.S., says it might be because most people with a genetic susceptibility to high blood pressure are taking blood pressure medication.

There is evidence these drugs have the potential to alter brain chemicals and reduce inflammation ‘in ways that confer a reduced risk of Alzheimer’s’, he says.

BEETROOT JUICE CAN BE A HELP 

A recent U.S. study found drinking Montmorency cherry juice may be as effective at reducing blood pressure as taking medication.

The research, published in The American Journal of Clinical Nutrition, involved just 15 people, but found that 60ml of the juice per day was linked to a 7 per cent drop in blood pressure for three hours afterwards. It’s thought to help reduce arterial stiffness.

There’s a lot more evidence for beetroot lowering blood pressure, says Professor Padmanabhan. ‘It contains nitrates that the body converts into nitric oxide, which naturally widens blood vessels, lowering blood pressure.’

Beetroot is easily juiced, and you can get enough to have a blood pressure-lowering effect in one daily 250ml glass.

In a study at Queen Mary University of London, this amount was shown to lower systolic blood pressure by eight points and diastolic by four points in four weeks.

LOW BLOOD PRESSURE CAN BE RISKY

While high blood pressure is classed as a consistent measurement of over 140/90, even readings over 120/80 — which is seen as normal — increase your risk of stroke.

‘It’s not the case that 139/89 is fine and risk only starts when you reach 140/90,’ says Pippa Tyrrell, a professor of stroke medicine at the University of Manchester. 

‘There’s a gradation of risk that goes up as your blood pressure does. So, if your doctor tells you your blood pressure measurement is borderline, also known as prehypertension, you should still take it seriously.’

Prehypertension (classed as measurements between 120/80 and 139/89) can be reversed with lifestyle factors. These include improving fitness (which encourages the arteries to dilate), getting down to a healthy weight (taking strain off the heart), stopping smoking and cutting back on salt (salt increases fluid levels in the blood, increasing pressure on the arteries).

Having low blood pressure — anything below 90/60 — is not a risk to health, but it can cause some people to feel dizzy on standing and increase the risk of falls. Low blood pressure has also been associated with depression in older people — possibly because of a link between proteins that control blood pressure and mood.

WE ALL GET HIGH BLOOD PRESSURE

Blood pressure increases as we get older, as blood vessels stiffen with age. For this reason, the advice is to get your levels checked every five years throughout adulthood.

‘This is particularly important for women around menopause, when blood pressure can rise markedly as oestrogen levels fall,’ says Professor Tyrrell. Oestrogen helps blood vessel walls relax.

However, some people need their blood pressure checked annually as they’re taking medication or because they have health problems that raise the risk of a rise.

These include women on hormone replacement therapy or the Pill, migraine sufferers and those with a family history of high blood pressure or stroke.

It’s also a good idea to get your blood pressure checked if you gain weight. A 2014 study by the Mayo Clinic in the U.S. found even a relatively small gain, such as 5lb to 7 lb over eight weeks, increases systolic blood pressure by four points.

However, everyone in Western countries at least will get high blood pressure if they live long enough. ‘It’s a natural factor of ageing,’ says Sandosh Padmanabhan, a professor of cardiovascular genomics and therapeutics at the University of Glasgow.

‘But it is accelerated in people who have unhealthy lifestyles.’

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