Fiber can be soluble or insoluble.  Soluble fiber is sometimes called viscous.  Soluble fibers are primarily pectin, beta-glucan, and guar gum, while insoluble are cellulose and lignin.  They are complex carbohydrates made by plants for their cell walls.  Insoluble has been most strongly connected with improved longevity, although soluble fibers can lower cholesterol.  Soluble fiber is found in oats, barley, citrus, soybeans, beans, and peas, while insoluble is primarily in wheat, rye and vegetables.  However, in fact, all of these contain both types of fibers.

The consumption of whole grains is an extremely important part of a healthy diet.  In fact, in a large study of 7th Day Adventists with excellent dietary and life habits, only the consumption of whole wheat, rye, and nuts were linked to living longer.  Refined flour and sugar are very unhealthy and have been linked with increased levels of illness and earlier death.  Whole grain wheat and rye have very high anti-oxidant values.  Whether this plays a role in their much lower levels of heart disease, stroke, and premature death, no one knows. 

The American Heart Association now recommends six servings of whole grains per day.  Whole grain wheat and rye, which have insoluble fiber, are clearly beneficial, but oats, which have soluble fiber, have not been found to lower death rates despite their ability to lower cholesterol somewhat.

Whole Grain Breakfast Cereal Lowered Total Mortality 17%: In a 5.5 year study of 86,190 US male physicians ages 40-84 and free of known CVD and cancer at baseline, there were 3114 deaths from all causes, including 1381 due to CVD (488 myocardial infarctions and 146 strokes). Whole-grain breakfast cereal intake was inversely associated with total and CVD-specific mortality, independent of age; body mass index; smoking; alcohol intake; physical activity; history of diabetes, hypertension, or high cholesterol; and use of multivitamins. Compared with men who rarely or never consumed whole-grain cereal, men in the highest category of whole-grain cereal intake (> or = 1 serving/d) had multivariate-estimated relative risks of total and CVD-specific mortality of 0.83 (P < 0.001) and 0.80 (P < 0.001). Total and refined-grain breakfast cereal intakes were not significantly associated with total and CVD-specific mortality. These findings persisted in analyses stratified by history of type 2 diabetes, hypertension, and high cholesterol.

Whole Wheat, Rye, But not Oats Lower Strokes and Heart Disease: 3,588 adults over 64 and free of heart disease completed a food frequency questionnaire. During 8.6 years of follow-up, there were 811 incidents of stroke and heart disease (CVD). After adjustment for age, sex, education, diabetes, ever smoking, pack-years of smoking, daily physical activity, exercise intensity, alcohol intake, and fruit and vegetable fiber consumption, cereal fiber consumption was inversely associated with incident CVD (P =.02), with 21% lower risk (hazard ratio [HR], 0.79) in the highest quintile of intake, compared with the lowest quintile. Neither fruit fiber (P =.98) nor vegetable fiber (P =.95) were associated with incident CVD. When CVD events were separately evaluated, higher cereal fiber intake was associated with lower risk of total stroke and ischemic stroke and a trend toward lower risk of ischemic heart disease death. Dark breads such as wheat, rye, or pumpernickel were associated with a lower risk of incident CVD (HR, 0.76) rather than cereal fiber from other sources. Mozaffarian D, Kumanyika SK, Lemaitre RN, Olson JL, Burke GL, Siscovick DS. University of Washington. JAMA. 2003 Apr 2;289(13):1659-66

Whole Grain Effect Not Cholesterol Related: Between 1996 and 2001 an accumulation of five very large cohort studies in the USA, Finland and Norway have all reported that subjects consuming relatively large amounts of whole grain cereals have significantly lower rates of coronary heart disease. This confirms an earlier small British study. The protective effect does not seem to be due to cholesterol-lowering. Cereal grains and coronary heart disease. Truswell AS. University of Sydney. Eur J Clin Nutr. 2002 Jan;56(1):1-14. Ed: Oatmeal lowers cholesterol a little; wheat and rye do not.

7^th Day Adventist Nuts & Whole Wheat Markedly Reduce Heart Attacks: Arch Intern Med ’92 152:1416-24 GE Fraser, Loma Linda. A study of 31,208 non-Hispanic European-Americans found that those eating nuts four or more times had 51% fewer non-fatal heart attacks (a RR .49 for nonfatal MI). Those usually consuming whole wheat had 44% fewer non-fatal heart attacks (RR .56 and fatal MI .89 vs. white bread). Beef men eating three times a week had a 131% increase in death from coronary heart disease (RR 2.31 for fatal CHD).

Bran May Be Even More Effective; 18% Lower Heart Disease with Whole Grains: In a 14-year follow-up study of 42,850 male health professionals ages 40-75 at baselinethere were 1818 cases of CHD. After cardiovascular disease risk factors and the intakes of bran and germ added to foods were controlled for, the hazard ratio of CHD between extreme quintiles of whole-grain intake was 0.82 (P=0.01). The hazard ratio of CHD in men with the highest intake of added bran was 0.70 compared with men with no intake of added bran (P= 0.001). Added germ was not associated with CHD risk. Intakes of whole grains, bran, and germ and the risk of coronary heart disease in men. Jensen MK, et al. Harvard. Am J Clin Nutr 2004 Dec;80(6):1492-9.

Whole Grains Help the Heart: In a 10 year follow-up of 75,000 nurses, researchers found strong decrease coronary heart disease especially in non-smokers for high whole grain intake after correcting for other factors with an RR 0.49 for highest quintile. Willett, W.C. The American Journal of Clinical Nutrition. 1999, Sep, v70, n3, p412-419.

Whole Grains Meta-Analysis: 17% Lower Mortality: 12 studies reviewed showing 26% decreased risk for coronary heart disease, decreased LDL cholesterol and TG. Whole grains are also good against cancers of the GI tract, breast, and prostate. Whole wheat has very high anti-oxidant values. Whole grain breakfast cereals 2200-3500 TE (Trolox Equivalents), fruits 600-1700 (plums 2200, grapes 1700, apples 1300, banana 1100, but cantaloupe 200, melons 100, raisins 6400 (per 100 g.), berries 3700 especially high pigmented blackberries 5500, raspberries 5100, blueberries 3300, strawberries 3100, prunes 5800, concord grape juice 1500 but grapefruit-orange-apple all 400-300, vegetables in general 450, red cabbage 1400. Raisins increased cereal TEs. Iowa Women’s Health Study 17% decreased mortality whole grains. Fiber in brown rice 3.3, cooked oatmeal 4.0, whole grain breakfast 3.0+. All from J Amer Coll Nutr 6/2000

Whole Grains & Bran Help Lose Weight: In an 8-year follow-up study of 27 082 men ages 40-75, in multivariate analyses, an increase in whole-grain intake was inversely associated with long-term weight gain (P< 0.0001). For every 40-g/d increment in whole-grain intake from all foods, weight gain was reduced by 0.49 kg. Bran that was added to the diet or obtained from fortified-grain foods further reduced the risk of weight gain (P = 0.01): for every 20 g/d increase in intake, weight gain was reduced by 0.36 kg. Changes in cereal and fruit fiber were inversely related to weight gain. No associations were observed between changes in refined-grain or added germ consumption. Changes in whole-grain, bran, and cereal fiber consumption in relation to 8-y weight gain among men. Koh-Banerjee P, et al. Harvard. . Am J Clin Nutr 2004 Nov;80(5):1237-45.

Whole Wheat & Rye Improve Colon Markers: Both high-fiber rye and wheat foods increased fecal output by 33-36% (P = 0.004) and reduced fecal beta-glucuronidase activity by 29% (P = 0.027). Postprandial plasma insulin was decreased by 46-49% (P = 0.0001) and postprandial plasma glucose by 16-19% (P = 0.0005). Rye foods were associated with significantly (P = 0.0001) increased plasma enterolactone (47% and 71%) and fecal butyrate (26% and 36%), relative to wheat and low-fiber options, respectively. Whole-grain rye and wheat foods and markers of bowel health in overweight middle-aged men. McIntosh GH, Noakes M, Royle PJ, Foster PR. Am J Clin Nutr 2003 Apr;77(4):967-74

Whole Grains Might Lower Excessive Blood Pressure Slightly: In a DB PC study of 110 adults ages 30-65 years with untreated, but higher than optimal BP or stage-1 hypertension, those on 8 g/day of water-soluble fiber from oat bran had decreases in systolic blood pressure were -1.8 mmHg following 12 weeks, and -2.2 mmHg following 6 weeks (P = 0.09). Diastolic blood pressure dropped 1.0 mmHg. Effect of dietary fiber intake on blood pressure: a randomized, double-blind, placebo-controlled trial. He J, et al. Tulane University. . J Hypertension 2004 Jan;22(1):73-80.

Whole Grains Lower Coronary Heart Disease: Between 1996 and 2001 an accumulation of five very large cohort studies in the USA, Finland and Norway have all reported that subjects consuming relatively large amounts of whole grain cereals have significantly lower rates of CHD. Eur J Clin Nutr 2002 Jan;56(1):1-14

Oatmeal Reduced Hypertension in Very Small Study: Study of 18 hypertensives given oatmeal daily vs. low fiber cereal for 3 weeks found a decrease in BP of 7 systolic/5 diastolic. Also a 9% decrease in cholesterol and a 14% decrease in LDL. J Fam Pract 2002 Apr;51(4):369; Oat ingestion reduces systolic and diastolic blood pressure in patients with mild or borderline hypertension: a pilot trial. Keenan JM, Pins JJ, Frazel C, Moran A, Turnquist L.

Oatmeal Beats Refined Wheat for Glucose, LDL, Chol, BP: 88 hypertensive adults randomly assigned 12 weeks on whole oats or refined wheat. Glucose down 15mg. 72% able reduce hypertensive meds. U Minn. J Fam Pract 2002 Apr;51(4):353-9; Do whole-grain oat cereals reduce the need for antihypertensive medications and improve blood pressure control? Pins JJ, Geleva D, Keenan JM, Frazel C, O'Connor PJ, Cherney LM.; However, no benefit found in 36 pt random study. J Nutr 2002 Mar;132(3):394-8

Oats Better Than Whole Wheat for LDL/HDL: 36 overweight men ages 50-75 ate 12 weeks of oatmeal or 12 of whole wheat hot cereal or Frosted Mini-Wheats at 60 g oatmeal/day (two large servings). LDL, especially small LDL, decreased for oats (17%) but increased for wheat (60%). LDL/HDL decreased 6% oats, increased 14% wheat. Oats have soluble fiber beta-glycan; wheat has insoluble fiber. Small, dense LDL are more atherogenic (pattern B lipoprotein profile). Cholesterol decreased 2%  for oats and increased 6% for wheat. Triacylglycerol decreased 6% on oats while increasing 22% on wheat. There was no decrease in HDL with oats. 1/16 of American whole grain intake is oatmeal, 55% whole grain bread, 1/8 popcorn, 1/6 other whole grain cereals. Am J Clin Nutr 2002 Aug;76(2):351-8; High-fiber oat cereal compared with whole wheat cereal consumption favorably alters LDL-cholesterol subclass and particle numbers in middle-aged and older men. Colorado State U. Davy BM, Davy KP, Ho RC, Beske SD, Davrath LR, Melby CL. Study compared oats to wheat cereal with both providing 14g fiber/d.

Fiber May Helps: A Harvard J of Cardiology study of 38,000 female health care professionals over 45 found quartile high in fiber had less heart disease. 1/26/02

Whole Wheat Diet Lost More Weight: 12 week study with a puffed whole wheat product. Moderately obese women lost 10 vs 5 pounds on control diet. Use of an expanded-whole-wheat product in the reduction of body weight and serum lipids in obese females. Fordyce-Baum MK, Langer LM, Mantero-Atienza E, Crass R, Beach RS. Am J Clin Nutr 1989 Jul;50(1):30-6

Legumes Decrease CHD, CVD: Legume consumption (which is high in soluble fiber) was significantly and inversely associated with risk of CHD (P =.002 for trend) and CVD (P =.02 for trend) after adjustment for established CVD risk factors. 9632 adults 19 yr f/u NHEFS Study. Legume consumption 4 times or more per week compared with less than once a week was associated with a 22% lower risk of CHD (relative risk, 0.78) and an 11% lower risk of CVD (relative risk, 0.89). Legume consumption and risk of coronary heart disease in US men and women: NHANES I Epidemiologic Follow-up Study. Bazzano LA, He J, Ogden LG, Loria C, Vupputuri S, Myers L, Whelton PK. Arch Intern Med 2001 Nov 26;161(21):2573-8. Tulane.

Whole Grains Big Help Lowering Stroke Risk: Compared with women in the lowest quintile of whole grain intake, women in the highest quintile of whole grain intake (2.7 servings per day) had a 43% lower risk of ischemic stroke. Nurses’ Study of over 75,000 for 14 yr. JAMA 9/2000

Whole Grains, Cereal Fibers, Dietary Magnesium Protect Against Type II Diabetes: Refined grains, glycemic index, fruits and vegetables had no impact. Prospective 6 yr Iowa study of 36000 women . Am J Clin Nutr 2000 Apr;71(4):921-30

Whole Grains & Polyunsaturated Fats Good Against Diabetes: a higher intake of polyunsaturated fat and possibly long-chain n-3 fatty acids could be beneficial, whereas a higher intake of saturated fat and trans-fat could adversely affect glucose metabolism and insulin resistance. In dietary practice, exchanging non-hydrogenated polyunsaturated fat for saturated and trans-fatty acids could appreciably reduce risk of Type II diabetes. In addition, a low-glycemic index diet with a higher amount of fiber and minimally processed whole grain products reduces glycemic and insulinemic responses and lowers the risk of Type II diabetes. Diabetologia 2001 Jul;44(7):805-17

Yet Another Study Shows Whole Grains Protect Against Diabetes: The Insulin Resistance Atherosclerosis Study of 956 adults found that consumption of whole grain foods, primarily dark breads (whole wheat and whole rye) increased insulin sensitivity.  A decrease in insulin sensitivity is one of the best predictors of diabetes. Angela Liese, Univ South Carolina. Am J Clin Nutr. 2003;78:985-971.

Buckwheat Helped Diabetes in Rats: A study has found that buckwheat, a whole grain used in making some pancakes and soba noodles, may be beneficial in the management of diabetes. In a controlled study, extracts of the seed lowered blood glucose levels by 12 percent to 19 percent when fed to diabetic rats. Dec. 3, 2003, Journal of Agricultural and Food Chemistry