A team of researchers, led by Dr Dagfinn Aune at Imperial College London, said the results "strongly support dietary recommendations to increase intake of whole grain foods in the general population".
Whole grains are high in fibre, vitamins and folic acid, essential fatty acids, protein, and antioxidants including vitamin E, according to the British Dietetic Association.
Researchers carried out a systematic review and meta-analysis of 45 published studies on whole grain consumption in relation to several health outcomes and all cause mortality.
They included more than 7,000 cases of coronary heart disease, 2,000 cases of stroke, 26,000 cases of cardiovascular disease, 34,000 deaths from cancer, and 100,000 deaths among 700,000 participants.
For those who consumed 90g of whole grain products per day, the following was observed:
Coronary heart disease risk was reduced by 19%
Cardiovascular disease risk was reduced by 22%
Risk of death by stroke was reduced by 14%
Cancer risk was reduced by 15%
Respiratory disease risk was reduced by 22%
Risk of infectious disease was reduced by 26%
Diabetes risk was reduced by 51%
The greatest health benefit was seen for people who went from not eating whole grains at all, to consuming two servings per day - equivalent to 32 g/day, such as 32 g of whole grain wheat or 60 g product/day, such as 60 g of whole grain wheat bread.
Further reductions in health risks were observed in those who had up to 7.5 servings of whole grains a day, which is equivalent to 225g of whole grain products such as bread.
A large body of evidence has emerged on the health benefits of whole grain foods over the last 10-15 years.
Grains are one of the major staple foods worldwide and provide, on average, 56% of energy intake and 50% of protein intake.
Researchers said that recommendations on the daily amount and types of whole grain foods needed to reduce risk of chronic disease and mortality have often been unclear or inconsistent.
They recommend for people to increase their intake of whole grains and to choose whole grains rather than refined grains as much as possible.
They noted there were several limitations with their analyses, and called for more research to determine health benefits of different types of whole grains in different geographical regions - as most of the current evidence is from the US and fewer studies have been conducted in Europe, Asia and other regions.
They also said that studies of specific diseases, and less common causes of deaths, are needed.
A similar study into whole grains was recently carried out by Harvard University researchers who found that a diet rich in whole grains, such as brown rice, oats and Weetabix, could significantly reduce risk of early death.
They said that the more whole grains a person eats, the greater the health benefit.
Qi Sun, who led the research, said low-carbohydrate diets that ignore the health benefits of whole grain foods “should be adopted with caution” as they could potentially lead to heart disease and early death.
“Based on the solid evidence from this meta-analysis and numerous previous studies that collectively document beneficial effects of whole grains, I think healthcare providers should unanimously recommend whole grain consumption to the general population as well as to patients with certain diseases to help achieve better health and perhaps reduce death."
Victoria Taylor, senior dietician at the British Heart Foundation, said of the findings: “Eating more whole grains is a simple change we can make to improve our diet and help lower our risk of heart and circulatory disease.
“Unlike in the US, the UK doesn’t have specific recommendations for the number of portions of whole grains we should eat everyday, but we do have a recommendation on the amount of fibre we should eat.
“Whole grains are a great way of increasing the level of fibre in our diets and, on average, our intake of fibre is not meeting guidelines.
“Choosing brown rice, whole-wheat pasta, wholemeal or granary bread instead of white and swapping to wholegrain breakfast cereals like porridge are all simple ways to help us up our fibre and wholegrain intake.”
Looking to add more whole grains into your diet? Here are 10 ways to do it.
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