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NutrInsight • Whole grain and health: new evidence
2.2 Cardiovascular diseases
Cardiovascular diseases, including coronary heart disease, ischaemic heart disease, stroke and peripheral vascular disease are the most common causes of death in developed countries.
Observational evidence
Some of the impressive observational studies based on prospective evidence from cohorts on whole grain in relation to CVD are summarised in Table 2. Even after allowing for the many confounding factors mentioned above, substantial positive effects are still seen for CVD and stroke.
Only significant differences are reported. CIs are confidence intervals for the 5th quintile. HR: Hazard Ratio; RR: Relative Risk.
Table 2: Summary of large scale observational studies showing a benefit of increase whole grain consumption on CvD risk
Source: Adapted from Seal and Brownlee, 2010
Three separate meta-analyses have been performed [Anderson et al., 2000 ; Anderson, 2003 ; Mellen et al., 2008] on the results of many of these observational studies and the consistency of the evidence has led one author to state “In light of this consistent evidence, policy makers, scientists and clinicians should redouble efforts to incorporate clear messages on the beneficial effects of whole grains into public health and clinical practice endeavours” [Mellen et al., 2008].
Intervention studies
Two systematic reviews - Ruxton (2008) and Kelly (2007) - have summarised the evidence from intervention trials which have investigated the effect of whole grain on risk factors for CVD and have not produced such a consistent picture. The first review (restricted to studies on oats) provided evidence that regular oat consumption is an effective dietary strategy for helping to attenuate CVD risk. Despite the consistency of effects seen in trials of whole grain oats [Ruxton and Derbyshire, 2008], the second review only found weak evidence for a reduction in LDL cholesterol concentrations and warned that “the positive findings should be interpreted cautiously” [Kelly et al., 2007]. Most trials have been conducted in “at risk” populations with small numbers of subjects. Results from larger trials are gradually being published; some support the consistent message from observational studies but some do not.
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