High blood pressure

Joanna Evans reports on eight ways you can eat to beat high blood pressure

It’s common knowledge that a healthy diet is one of the best ways to keep blood pressure levels in check. Eating lots of fruit and veg, opting for whole foods over processed foods, watching your salt intake and avoiding too much alcohol are a few small steps you can take that may have a big impact on your blood pressure readings.

But there are some foods that stand out from the rest and are showing promise as powerful blood-pressure-reducers on their own. Some are even proving to be as potent as antihypertensive drugs, and they don’t come with a long list of nasty side-effects.

Here’s a roundup of the foods that scientists are finding have a natural blood-pressure-lowering effect. Adding them to your diet could be a simple way to help reduce high blood pressure, or stop it from developing in the first place.

Raisins

If you have slightly higher than normal blood pressure-what doctors like to call prehypertension-try a daily dose of raisins. According to a study just published, snacking on a handful of raisins three times a day significantly lowered both systolic (the top number) and diastolic (the bottom number) blood pressure in as little as a month. Eating other kinds of snacks, like crackers, cookies or other fruits, had no effect on blood pressure. Raisins have high fibre and potassium contents, which might explain their blood-pressure-

Berries

Upping your intake of fruits and vegetables in general is good for your blood pressure, but berries seem to be especially beneficial. In a trial of middle-aged men and women, those eating berries (100 g) and drinking a berry juice daily saw systolic blood pressure reductions of up to 7.3 mmHg along with positive changes in cholesterol and platelet function (blood cells involved in clotting).

Bilberries, lingonberries, blackcurrants, strawberries, chokeberries and raspberries were all on the menu.3 Anthocyanins-flavonoid pigments that give berries their bright colours-may be responsible for the heart-healthy effects. In fact, one 14-year study found that the people who ate the largest amounts of anthocyanins were 8 per cent less likely to be diagnosed with high blood pressure than those eating the lowest amounts.4

Beetroot

Diets that include foods rich in nitrate (and its byproduct nitrite) like beetroot have been associated with lower blood pressure, and beetroot itself appears to have vasodilator and vasoprotective effects. In one study, people who drank a glass of beetroot juice a day had significantly lower blood pressure just 24 hours later.1 Another study reported similar effects when men were given beetroot-containing bread.2

It’s thought that the nitrate is responsible, as it increases levels of nitric oxide in the blood, which dilates blood vessels and, in turn, lowers blood pressure. Other nitrate-rich foods include aubergine (eggplant), cabbage, kale and lettuce.

Flaxseed

Rich in fibre and a good plant source of omega-3 fatty acids, flaxseed (or linseed) may be one of the best things you can add to your diet if you want to lower high blood pressure. In a placebo-controlled study of peripheral artery disease, where plaque builds up in arteries in the arms and legs, those who suffered from high blood pressure saw their systolic and diastolic readings drop dramatically after six months of eating 30 g/day of milled flaxseed.

The researchers called the results “one of the most potent antihypertensive effects achieved by a dietary intervention” and found they were comparable to those achieved by the currently available medications.5

Gazpacho

If you want to lower the odds of your developing high blood pressure in the future, start making gazpacho (see page 54 for our Food as Medicine columnist Annemarie Colbin’s recipe). This tomato-based soup could cut your chances of developing high blood pressure by 27 per cent, according to a study of people at high risk for heart disease. The soup’s ingredients-which include tomato, cucumber, garlic and olive oil-have been individually linked to lower blood pressure in earlier studies, but this is the first to show that gazpacho has such an effect. Although it contains salt, the soup’s high levels of carotenes, vitamin C and polyphenols seem to outweigh any adverse effects the salt may have.8

Eggs

Eggs have had a bad rap because of their high cholesterol, but the latest evidence suggests they might actually be good for the heart. Scientists have discovered that something in egg whites-a peptide called RVPSL-acts just like the popular antihypertensives known as ACE (angiotensin-converting enzyme) inhibitors, but with no apparent toxic effects. According to Zhipeng Yu of Jilin University in China, who’s leading the research, RVPSL reduces blood pressure about as much as a low dose of the ACE inhibitor captopril. And the peptide appears to retain its beneficial effects even after cooking.10 As the research has so far only been done in test-tube and animal studies, the results may not be the same in humans. But eating an egg (or just the egg whites) a day could be a simple and safe way to help keep blood pressure levels in check.

Dark chocolate

A little bit of what you fancy really can do you good. Just a couple of squares a day (6.3 g) of dark chocolate cut systolic blood pressure by 2.9 mmHg and diastolic blood pressure by 1.9 mmHg in a study of people with prehypertension. Plus they didn’t put on any weight. It’s got to be the dark stuff though, which is high in heart-healthy compounds called flavanols; white chocolate had no effect on blood pressure.9

Olive oil

A major component of the heart-healthy Mediterranean diet, olive oil has been found to slash blood pressure. But it needs to be the extra virgin variety, which contains the highest levels of potent antioxidants called polyphenols. In a small but high-quality trial of women with mildly raised blood pressure, those consuming 30 mg/day of polyphenol-rich olive oil saw their systolic blood pressure fall by 7.91 mmHg and their diastolic by 6.65 mmHg. There were no such changes in the group using polyphenol-free olive oil.7