Multivitamins, fish oil and antioxidants are among the products taken by millions of people which make no difference to mortality rates, experts found.
A team of academics at West Virginia University in the US analysed 277 trials, involving a combined 1 million people, to determine the effects of 16 different nutritional supplements and eight dietary interventions.
They found the majority made no difference to mortality or cardiovascular disease.
Some 34 percent of adults take vitamins and supplements every day - driving a market that has grown 6 percent in five years is now worth an annual $37 billion globally.
But experts are increasingly skeptical about the worth of the pills, with many pointing out that supplements do provide a short cut to a healthy diet and can never replace real food.
The researchers, writing in the Annals of Internal Medicine journal, found some supplements provided a degree of protection against specific health problems.
Folic acid, for example, showed some protection against stroke.
And omega-3 fatty acids, which are present in fish oils, protected against heart attacks.
But they found multivitamins, selenium, vitamin A, vitamin B6, vitamin C, vitamin E, vitamin D and iron had no significant effect on either early death or cardiovascular disease.
The researchers also found dietary interventions, such as the Mediterranean diet, rich in vegetables, olive oil and fish, made no difference to mortality or heart health.
Surprisingly, reducing fat did not cut heart disease and cutting salt levels did cut death rates, but not heart problems.
Experts last night welcomed the findings but said the study could not provide the whole story.
Victoria Taylor, senior dietitian at the British Heart Foundation, said: ‘Studies on dietary approaches are very difficult to conduct and may vary widely in their approaches and definitions of the interventions.
‘It would also be all but impossible to carry out a research trial where you carefully controlled the diets of thousands of people over many years.’
Professor Susan Jebb of the University of Oxford, said: ‘This review confirms the vast majority of previous research that has failed to find benefits of most nutritional supplements.
‘[It] finds no good evidence that vitamin and mineral supplements are associated with a reduction in premature death or in cardiovascular disease.
‘Except to prevent or correct specific deficiencies (e.g. Vitamin D), or in specific circumstances such as folic acid supplements in early pregnancy to prevent neural tube defects, there is generally good agreement that dietary supplements should not be recommended to the general population.’
But she disagreed with the assertion that cutting fat or salt does not benefit health.
‘The suggestion that dietary interventions have no benefit does not reflect the totality of the evidence,’ she said.
Catherine Collins, an NHS dietitian in Surrey, said: ‘Using an umbrella review to assess dietary research on heart health is like trying to paint a masterpiece using a fence brush - the broad strokes create an impression, but the nutritional nuance, the clinically relevant fine detail, is lost.’
The Daily Mail
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