The March 2008 Consumer Reports says that eating whole grains is the #1 action you can take to improve your health (besides quitting smoking).
Repeated studies over decades have shown that whole grains can reduce your risk of stroke by up to 36%, heart disease by up to 28%, and Type 2 diabetes up to 30%.
Whole grains also reduce your risk of getting asthma, inflammatory disease, cancer, high blood pressure, and much more.
The Whole Grains council has the latest whole grain health studies, here are some of the articles listed there:
Whole Grain and Fiber Cut Prediabetic Conditions European Journal of Clinical Nutrition, July 2012; 66(7):819-24. (Heikkilä et al.)
White Rice Significantly Increases Diabetes Risk British Medical Journal. 2012 March 15; 344:e1454. (Hu et al.)
Whole Grain Bread Yes, Red Meat No European Journal of Nutrition, 2012 March 18. (Montonen et al)
Whole Grain Decreases Body Fat Compared to Refined Grain The Journal of Nutrition, April 2012; 142(4):710-6. (Kistensen et al.)
Weight Loss, Decreased Fat with Whole Grain Journal of Nutrition, Feb 22, 2012. (Kristensen et al.)
Early Infant Feeding and Celiac Prevention Alimentary Pharmacology & Therapeutics, 2012 August 21. (Szajewska et al.)
Weight Loss, Decreased Fat with Whole Grain Journal of Nutrition, Feb 22, 2012. (Kristensen et al.)
Produce, Whole Grains, Tea, Chocolate Reduce Stroke Risk Stroke, December 1, 2011. (Rautiainen et al.)
Whole Grains Reduce Colon Cancer Risk 20% British Medical Journal, 10 November 2011; 343:d6617 (Aune et al.)
Adolescent Whole Grain Intake Linked to Lower Insulin, Higher Folate Journal of the American Dietetic Association, 3 Nov 2011 (Hur et al.)
Whole Grain Breakfast Cereals Reduce Hypertension Clinical Nutrition. August 23, 2011
48g of Whole Grains Daily Cuts Blood Pressure British Journal of Nutrition, April 18, 2011: 1-4
Whole Grain Rye Bread Linked to Lower Mortality The Journal of Nutrition, April 1, 2011; 141(4):639-44
Whole Grain Intake Associated with Less Abdominal Fat American Journal of Clinical Nutrition. November 2010; 92(5):1165-71.
Prebiotic Potential of Whole Maize Cereals British Journal of Nutrition. Nov 2010; 104(9):1353-6 (Epub May 21, 2010)
Black Rice Bran Protects Against Inflammation Journal of Agricultural and Food Chemistry, Sept 22, 2010; 58(18):10007-15.
Indigestible Carbs May Explain Diabetes Benefits of Whole Grains Journal of Nutrition, September 1, 2010
Whole Grains Lower C-reactive protein (CRP), Improve Reproductive Outcomes Journal of Nutrition. September 2010; 140(9):1669-1676. doi: 10.3945/jn.110.124164
Switch to Brown Rice Reduces Diabetes Risk in Men and Women Archives of Internal Medicine. June 14, 2010; 170 (11): 96-9.
INTAKE OF WHOLE GRAINS LOWER THAN RECOMMENDED AMONG ADOLESCENTS Journal of the American Dietetic Association, Feb 2010;110(2):230-7.
Rye Reduces Body Weight Compared to Wheat Nutrition. February 2010; 26(2): 230-9. Epub 2009 Jul 31.
Barley Controls Blood Sugar Better American Journal of Clinical Nutrition, January 2010; 91(1):90-7. Epub 2009 Nov 4.
Oats May Reduce Asthma Risk in Children British Journal of Nutrition, January 2010; 103(2):266-73
And even more studies if you click here