Reference Number: 682
Year: 2016
Link: Link to original paper
Health: Cancer | Heart Disease
Nutrition: Whole grain
Summary
ABSTRACT
Objective: To quantify the dose-response relation between consumption of whole grain and specific types of grains and the risk of cardiovascular disease, total cancer, and all cause and cause specific mortality. Data sources: PubMed and Embase searched up to 3 April 2016. Study selection: Prospective studies reporting adjusted relative risk estimates for the association between intake of whole grains or specific types of grains and cardiovascular disease, total cancer, all cause or cause specific mortality. Data synthesis: Summary relative risks and 95% confidence intervals calculated with a random effects model. Results: 45 studies (64 publications) were included. The summary relative risks per 90 g/day increase in whole grain intake (90 g is equivalent to three servings, for example, two slices of bread and one bowl of cereal or one and a half pieces of pita bread made from whole grains) was 0.81 (95% confidence interval 0.75 to 0.87; I2=9%, n=7 studies) for coronary heart disease, 0.88 (0.75 to 1.03; I2=56%, n=6) for stroke, and 0.78 (0.73 to 0.85; I2=40%, n=10) for cardiovascular disease, with similar results when studies were stratified by whether the outcome was incidence or mortality. The relative risks for morality were 0.85 (0.80 to 0.91; I2=37%, n=6) for total cancer, 0.83 (0.77 to 0.90; I2=83%, n=11) for all causes, 0.78 (0.70 to 0.87; I2=0%, n=4) for respiratory disease, 0.49 (0.23 to 1.05; I2=85%, n=4) for diabetes, 0.74 (0.56 to 0.96; I2=0%, n=3) for infectious diseases, 1.15 (0.66 to 2.02; I2=79%, n=2) for diseases of the nervous system disease, and 0.78 (0.75 to 0.82; I2=0%, n=5) for all non-cardiovascular, non-cancer causes. Reductions in risk were observed up to an intake of 210-225 g/day (seven to seven and a half servings per day) for most of the outcomes. Intakes of specific types of whole grains including whole grain bread, whole grain breakfast cereals, and added bran, as well as total bread and total breakfast cereals were also associated with reduced risks of cardiovascular disease and/or all cause mortality, but there was little evidence of an association with refined grains, white rice, total rice, or total grains. Conclusions: This meta-analysis provides further evidence that whole grain intake is associated with a reduced risk of coronary heart disease, cardiovascular disease, and total cancer, and mortality from all causes, respiratory diseases, infectious diseases, diabetes, and all non-cardiovascular, non-cancer causes. These findings support dietary guidelines that recommend increased intake of whole grain to reduce the risk of chronic diseases and premature mortality.
Summary of Paper
This large study, published in a prestigious journal set out to answer a question: Do people who eat more whole grains live longer and have lower risks of major diseases? To find out, the researchers combined results from many long?term population studies in a systematic review and meta?analysis. This approach allows them to look for consistent patterns across very large numbers of people.
The team searched for prospective cohort studies, studies that follow people over time, record their diets, and track who develops disease or dies. They included 45 studies involving hundreds of thousands of adults from different countries. These studies looked at whole?grain intake and outcomes such as:
- Cardiovascular disease (heart disease and stroke)
- Cancer
- All?cause mortality (death from any cause)
- Cause?specific mortality (e.g., heart disease deaths, cancer deaths)
The researchers then analysed whether higher wholegrain intake was linked to lower risks, and whether eating more whole grains provided additional benefit (dose?response analysis).
The results were remarkably consistent:
1. Higher whole?grain intake was linked to a lower risk of dying from any cause.
People who ate the most whole grains had a 16–18% lower risk of all?cause mortality compared with those who ate the least.
2. Whole grains were strongly protective against cardiovascular disease.
Higher intake was associated with a 20–25% lower risk of cardiovascular disease and heart?disease?related death.
3. Whole grains were linked to a lower risk of cancer.
People with the highest whole?grain consumption had about a 10–15% lower risk of developing cancer overall.
4. More whole grains generally meant more benefit.
The dose?response analysis showed that risk continued to fall as whole?grain intake increased, up to about 90 grams per day (roughly 3 servings). Beyond that level, the benefit appeared to level off.
5. Whole?grain foods such as whole?grain bread, oats, brown rice, and breakfast cereals all contributed to the protective effect.
Significance for the baker
This study provides strong evidence that eating more whole grains is associated with a lower risk of major chronic diseases and early death. The findings support dietary guidelines that encourage replacing refined grains (like white bread and white rice) with whole?grain alternatives. The results also suggest that even modest increases in whole?grain intake can make a meaningful difference to long?term health. For example, starting someone on a 20% wholegrain loaf and working up to 50%, 80% or even 100% over time can make a significant difference
