Taking vitamin D supplements could cut blood pressure by as much as some drugs, claim researchers.

A new study shows supplements lowered blood pressure in patients diagnosed with hypertension – high blood pressure – compared with those taking ‘dummy’ pills.

Vitamin D deficiency has been linked with high blood pressure, but until now there has been little scientific evidence that topping up levels of the vitamin in the blood makes a difference.

A new study, presented at the European Society of Hypertension (ESH) meeting in London, shows direct benefits from taking supplements for five months in winter.

Sun exposure tops up natural levels more effectively than through diet, but northern European countries like the UK only get adequate levels of UV light for seven months a year.

Around 90 per cent of the body’s supply of vitamin D comes from the action of sunlight on the skin.

Researchers studied patients visiting the Holstebro Hospital in Denmark, which is at the 56th Northern latitude – about the same latitude as Glasgow and Moscow).

Altogether 112 patients taking part had their initial levels of vitamin D measured, and then they were given either Vitamin D or a placebo (dummy pill) for 20 weeks. 92 of the 112 patients were found to have low levels of vitamin D at the start of the study.

The researchers found that those patients taking the vitamin D supplement of 75 mcg (correct) daily showed a significant reduction in central systolic blood pressure, blood pressure measured near the heart.

When compared to the placebo group, patients taking vitamin D had a cut in systolic blood pressure of 6.8 mmHg, while diastolic blood pressure was reduced by 1.7mmHg.

A high blood pressure reading is one that exceeds 140/90 millimetres of mercury. The first figure, the systolic pressure, corresponds to the ‘surge’ that occurs with each heart beat while the diastolic reading is the pressure in the ‘resting’ stage between beats.

High blood pressure is a major risk factor for heart disease and stroke.

Study leader Dr Thomas Larsen said ‘Probably the majority of Europeans have vitamin D deficiency, and many of these will also have high blood pressure.

‘What our results suggest is that hypertensive patients can benefit from vitamin D supplementation if they have vitamin D insufficiency.

‘Vitamin D would not be a cure for hypertension in these patients, but it may help, especially in the winter months.

‘However, it is important to stress, that this was a small study, and that larger studies are needed to provide solid evidence.’ ESH Vice-President, Professor Anna Dominiczak of Glasgow University, said ‘Until now, there has been little evidence of benefit from vitamin D to patents with hypertension.

‘The reduction in systolic blood pressure was quite significant – this is what powerful drugs do in trials.

‘This is an initial study, so it needs to be confirmed, but it is potentially interesting as part of an overall strategy for managing hypertension in patients with low levels of vitamin D.’ Vitamin D supplements are available in two forms – vitamin D2 and vitamin D3 – with D3 being more active and effective.

Deficiency has been linked to cardiovascular disease, type 2 diabetes, several cancers, and autoimmune conditions as well as osteomalacia, which is the painful manifestation of soft bones in adults.

Independent dietician Dr Carrie Ruxton said ‘Vitamin D is unusual in that much of the body’s supply comes from sunlight rather than food. In winter, however, sunlight is in short supply, particularly in a northerly country like Britain and blood levels of vitamin D can fall very low by the beginning of spring.

‘Official figures show around 25 per cent of adults are vitamin D deficient in the Spring and many would benefit from supplements.’ In the UK, the Food Standards Agency does not recommend a specific daily dose of vitamin D unless you are elderly, pregnant, Asian, get little sun exposure and eat no meat or oily fish when 10mcg is advised.

It says daily supplements of 25mcg are unlikely to cause harm.

The danger with taking excessive doses for long periods is that the body absorbs too much calcium, which could weaken bones and possibly damage liver and kidneys.

Campaigners searching for ways to tackle dementia, which affects more than 800,000 people in Britain, have hailed the findings by academics at Bristol University as “an important step forward”.

The study of almost 60,000 people in Britain over 60, found those taking a particular type of blood pressure lowering drug were 50 per cent less likely to develop Alzheimer’s, than those on other types of anti-hypertensive medication.

They were also 25 per cent less likely to develop vascular dementia, the second most common form of the brain-wasting disease.

The drugs which appear to have the most protective effect are called angiotensin II receptor blockers, or ARBs. They are commonly prescribed to under 55s to tackle high blood pressure. Millions are thought to take them already.

These affect the renin angiotensin system, which helps regulate blood pressure and fluid balance.

Another type of drug to affect this system, called angiotensin converting enzyme inhibitors (or ACE-Is), also appeared to have a protective effect, although it was only about half as strong.

Dr Patrick Kehoe of Bristol University’s school of clinical sciences and the charity Alzheimer’s Research UK, who co-authored the report, said it was the first large-scale trial to find such an association.

He said: “If these results are borne out in clinical trials, then we’ll have a swathe of drugs that could be used against Alzheimer’s.

“On a personal level I’m very excited because this is something I have been working on for a decade.”

However, he cautioned that their use to combat dementia was “a little way off” because the observational study, which used anonymised data from the General Practice Research Database, did not prove causation.

“That’s the million dollar question,” he added.

“Nobody should be rushing to their doctor saying they want to be put on these just yet.”

However, results of the trial, published in the Journal of Alzheimer’s Disease, did account for underlying differences in blood pressure between individuals.

This is important because people with high blood pressure are known to be at a higher risk of Alzheimer’s and vascular dementia than others.

Dr Kehoe thus explained that the halving of risk was over and above anything brought about by the drugs’ effect on lowering blood pressure.

He said laboratory studies showed that the drugs interacted with the root causes of Alzheimer’s and vascular dementia.

Dr Simon Ridley, head of research at Alzheimer’s Research UK, said: “This study highlights the potential for particular blood pressure drugs to help with Alzheimer’s disease. If these findings can be supported in clinical trials, this could be an important step forward.

“With over 820,000 people in the UK living with dementia, there is a desperate need to find new treatments and prevention strategies.”