Page 17 - Nutrinsight-2

Whole grain and health: new evidence • NutrInsight
Improved inflammatory status
Evidence for this possible mechanism comes from observational studies. Data from the Insulin Resistance Atherosclerosis Study showed that high whole grain consumers had decreased concentrations of the inflammatory markers, C-Reactive Protein (CRP) and Plasminogen Activator Inhibitor-1 ( PAI-1) [Masters et al., 2010]. Older women with T2D in the Nurses Study also showed reduced concentrations of CRP and another inflammatory marker, tumour necrosis factor receptor 2 (TNF-R2) with increase whole grain consumption
[Qi et al., 2006].
Gaskins showed that premenopausal women who had one, or more than one serving of whole grain per day had lower concentrations of CRP at all phases in their menstrual cycle [Gaskins et al., 2010].
Improved insulin response
Lower fasting plasma glucose and insulin concentrations in hyperinsulinaemic subjects consuming increased amounts of whole grains have been demonstrated e.g. [Pereira et al., 2002], but this is by no means consistent across studies [Keenan et al., 2002] and has rarely been replicated in intervention studies.
Data from the Multi-Ethnic Study of Atherosclerosis (MESA) (a prospective cohort study of older adults initiated in 2000) showed a significant trend for lower insulin concentrations and lower HOMA-IR (homeostatic model estimated insulin resistance) levels in the top quintile of whole grain consumption compared with the bottom quintile [Lutsey et al., 2007].
The best recent study used the glycemic clamp technique to measure insulin sensitivity [Andersson et al., 2007]. In this randomized crossover study, 22 women and 8 men were given either whole grain or refined grain products to include in their habitual daily diet for two 6-wk periods. Peripheral insulin sensitivity did not improve significantly between the two groups at the end of the experimental period.
One of the most cited studies for a whole grain effect on insulin response [Alminger and Eklund-Jonsson, 2008] showed lower post-prandial glucose and insulinemic response with whole grain, high amylose high beta glucan barley, and high beta glucan tempe. However it is not clear that this is a genuine whole grain effect or an effect due to some fermentation component in the tempe.
Improved vascular function
Data from the Health Professionals Study (prospective cohort study 1986-2004), after 18 years of follow- up [Flint et al., 2009], has shown that consumption of whole grain cereals reduce the risk of incident hypertension. However the intake of whole grain was particularly low in the lowest quintile of intake.
Whole grain can also reduce changes in vascular function [Erkkilä et al., 2005]. After 3.2 yrs follow-up in a prospective cohort study involving 229 postmenopausal women participating in the Estrogen Replacement and Atherosclerosis trial, progression in stenosis tended to be less in women with higher intake of cereal fibre (P = 0.10) or whole grain foods (P = 0.09), after adjustments for age, cardiovascular risk factors, and dietary intakes of saturated and polyunsaturated fat, cholesterol, and alcohol. Intakes of total, fruit, and vegetable fibre, and number of servings of refined grain, fruits, or vegetable were not associated with progression.
Improved lipid profile
In the Baltimore Longitudinal Study on ageing [Newby et al., 2007] significant changes in total and LDL cholesterol concentrations were seen with increasing whole grain intake.
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