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Whole grain, fiber and health

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					Whole grain, fiber, and health
             David Jacobs, PhD
Professor of Epidemiology, School of Public
       Health, University of Minnesota
 Guest Professor, Department of Nutrition,
              University of Oslo
 University of Class lecture September 23,
                     2005
        University of Oslo, Norway
What is a whole cereal grain?
     Go to Fulcher slide show
Fiber amounts in different
   whole cereal grains
           Fiber per 100 g of grain
wheat            12 g
oats             10.6 g
rye              14.6 g
corn             7.3 g
brown rice       3.5 g
refined wheat    <2 g
white rice       <2 g
How can we tell whether whole
grain consumption is good for
           health?
 1. Epidemiology
   1.   Cross-section
   2.   Case-control
   3.   Prospective
   4.   Long term clinical trial
 2. Feeding study
Overview of Study Design, 1

 • Cross-section
   –   Everyone sampled at one time
   –   Can’t define whether exposure or
       disease comes first (temporality)
   –   Any disease has already happened, so
       disease can cause changes in
       exposure
   –   Effect measures: risk difference,
       relative prevalence
Overview of Study Design, 2
 • Case-control
   –   Sample separately from cases and
       from controls
   –   Can’t define whether exposure or
       disease comes first (temporality)
   –   Any disease has already happened, so
       disease can cause changes in
       exposure
   –   Effect measures: prevalence odds
       ratio (approximately relative risk if
       disease is rare)
Overview of Study Design, 3
 • Prospective
   –   Cross-sectional sample excluding
       prevalent disease
   –   Exposure stated before disease is
       known (temporality well-defined)
   –   Disease has not happened, so it can
       not cause changes in exposure
   –   As in cross-section and case-control,
       level of nutritional exposure is
       naturally occurring and correlated with
       demographics and other behaviors
   –   Effect measures: risk difference or
       relative risk or relative hazard (if time
       to event is considered)
Overview of Study Design, 4
 • Long term clinical trial
   –   Cross-sectional sample excluding
       prevalent disease, randomly assigned
       to different nutritional exposures
   –   Temporality well-defined
   –   Assigned nutrition exposure
       uncorrelated with other factors, but
       other nutrition exposures are naturally
       occurring and correlated with
       demographics and other behaviors
   –   Effect measures: risk difference or
       relative risk or relative hazard (if time
       to event is considered)
Overview of Study Design, 5
 • Long term clinical trial
    (continued)
   – Very difficult to carry out over
     years
   – Successful examples include
     Lyon Diet Heart Study and
     PREDIMED (in recruitment
     phase)
Overview of Study Design, 6
 • Feeding study
   – Short term (hours, days or
     weeks)
   – Exposure assigned randomly
   – All food provided or
     supplemental food only provided
   – Excellent for study short term
     effects such as changes in body
     weight or plasma insulin (disease
     intermediaries)
How do we know what people
         are eating?
 • Epidemiology
   – Ask questions about diet
     • Short term recall (detailed, not
          representative of long term)
      •   Long term frequency (intuitive, less
          detailed, representative, guess
          work)
      •   Study what people actually eat
 • Feeding
   – Provide all or some food
   – Study what the researcher is
     interested in
   Common epidemiologic
representations of whole grain
 •   Dark bread
 •   Brown bread
 •   Whole wheat bread
 •   Brown rice
 •   Usual breakfast cereal
 •   Hot cereal
 •   Must ask about food in terms the
     participant understands, so if
     whole grain is not understood, the
     participant can’t tell you about it
Norwegian example using bread
   (1) how many slices of bread do you usually eat per day?
          (<2 slices per day; 2 ± 4; 5 ± 6; 7 ± 8; 9 ± 12; 13+)
   (2) what kind of bread do you eat most often? (store bought;
          home-baked)
   (3) If you buy, what type most often? (white bread, fine or
          light bread, whole grain or dark bread)
   (4) If you bake at home, what proportion of the flour is
          whole grain (dark)? (don't use whole grain flour; <1/4
          whole grain flour; 1/4- 1/2 whole grain flour; more
          than 1/2 whole grain flour).

   Based on a 24 hour recall, store bought whole grain bread
        was overestimated and used a recipe with less whole
        grain

   Whole grain bread score: the number of slices
      of bread eaten per day times the
      proportion of whole grain flour.
American example using breakfast
            cereal
   Ask usual breakfast cereal
   Refer to coding list for whole
      grain content of several
      hundred brand name products
   Does not account for people
      eating multiple products
American example using bread
  The term whole grain bread is not
     well known and is confused
     with organic (which is
     irrelevant) and multigrain
     (which be all refined)
  Dark bread in US and brown
     bread in UK identify most
     whole grain breads, but
     misclassifies breads containing
     dark color, such as molasses
Whole grain and cancer: case-
     control experience
 Chatenoud L, Tavani A, La Vecchia C,
    Jacobs DR Jr, Negri E, Levi F,
    Franceschi S. Whole grain food
    intake and cancer risk. Int J
    Cancer. 1998 Jul 3;77(1):24-8.

 Jacobs DR Jr, Marquart L, Slavin J,
     Kushi LH. Whole-grain intake and
     cancer: an expanded review and
     meta-analysis. Nutr Cancer.
     1998;30(2):85-96. Review.
    Meta-analysis of case-control studies of whole grain
              food intake and cancer, 1998
     Cancer Site              Studies Reduced Risk? Pooled Odds
Ratio
Gonadotrophic hormone-related
    Prostate                        1         1          0.9
    Breast, endometrium, ovary      6         6          0.85
Aerodigestive
    Upper aerodigestive             15        14         0.6
    Colon, rectum, and polyps       13        10         0.8
    Pancreas                         4         4         0.7
Other
    Brain                           3         2          0.7
    Lymphoma                        3         3          0.5
    Soft tissue sarcoma             2         2          0.3
    Bladder                         1         1          0.5
    Myeloma                         1         1          0.5
    Liver                           1         1          0.6
    Thyroid                         1         1          0.6
   Whole grain and heart
  disease/type 2 diabetes:
prospective study experience
 Jacobs DR Jr, Gallaher DD.
    Whole grain intake and
    cardiovascular disease: a
    review. Curr Atheroscler Rep.
    2004 Nov;6(6):415-23.
    Review.
Whole grain confounding with
      other behaviors
 Iowa Women’s Health Study
                  34,492 postmenopausal Iowa women, 1986;
                   levels adjusted for age and energy intake


                                   Whole grain intake     Refined grain intake
                                   Quintile    Quintile    Quintile Quintile
                                      1            5            1          5
Health Behaviors
Current smoker, %                      24.7        12.1        16.0        17.1
Vitamin supplement use, %              53.7        68.7        70.9        54.4
Physical activity
  % engaging in regular activity       30.3        45.5        49.5        30.0
Hormone replacement therapy
  % ever                               34.0        42.6        40.4        34.7
                 34,492 postmenopausal Iowa women, 1986;
                  levels adjusted for age and energy intake
                                          Whole Grain       Refined Grain
                                  Quintile   Quintile   Quintile   Quintile
                                       1         5        1           5
Other Aspects of Diet
Fruits and vegetables, no juice
  mean, servings/week                 34.1      39.9     45.5       28.6
Red meat, mean, servings/week          6.6       5.1      6.0        5.4
Keys score, mean, mg/dl               45.7      38.9     42.8       41.0
Sucrose, mean, g/day                  42.2      38.8     37.6       47.3
Constituent Nutrients
Dietary fiber, mean, g/day             16.3     22.3      21.7      17.1
Vitamin E, mean, IU/day                 8.9     10.1      10.2       9.0
Folate, mean, µg/day                  270.7     332.3     342.1     264.7
   Whole grain and cancer –
Norwegian and Iowa prospective
           studies
  Unpublished talk give in Montreal,
     American Association of Cereal
     Chemists, 2002
  Findings much less clear than in
     case-control studies
  Same questions and design as for
     heart disease and diabetes
   Iowa Women’s Health Study:
   Fiber in 2 groups with similar total grain
   fiber     71% grain fiber from whole 77% grain fiber from refined
                                 grain                               grain
                    3.6 - 6 g / 2000 kcal whole fiber   <3.6 g / 2000 kcal whole fiber
                    <3.6 g / 2000 kcal refined fiber 3.6 g / 2000 kcal refined fiber
Sample size                      7481                              3559
Whole grain fiber               4.7 ± 0.7                          1.3 ± 1.0
Refined grain                   1.9 ± 0.8                          4.5 ± 0.9
fiber
Total grain fiber               6.6 ± 1.0                          5.8 ± 1.2
Total dietary                  23.3 ± 5.3                         19.2 ± 4.5
fiber

                    Jacobs DR, Pereira MA, Meyer KA, Kushi LH. J Amer Col Nutr 2000
Iowa Women’s Health Study:
11-year relative risk of mortality in 11040 women:
cereal fiber in itself does not predict death
                               Hazard Rate Ratio (95% CI)
                                in 71% whole grain fiber
                                  eaters relative to 77%
                                 refined grain fiber eaters

      Total mortality                0.83 (0.73, 0.94)

      Coronary heart disease         0.89 (0.66,1.20)

      All cancer                     0.92 (0.75,1.12)

      All other mortality            0.83 (0.71, 0.97)
    Which direction from here?
Problems with whole grain theory, 1
    • Supported by selected feeding
        and supplement studies
    •   Reliability
    •   Validity
    •   Residual confounding
    •   A synergy model is consistent
        with the complexity of biology
    •   In vitro studies also suggest
        synergy
    Which direction from here?
Problems with whole grain theory, 2
    •   Fiber not the whole answer
    •   Myriad phytochemicals coexist with fiber
        in all plant foods
    •   These include enzymes, pesticides,
        antioxidant defense, signal transducers
    •   Though the nutrient model has some
        value, it seems more helpful to think of
        foods and food combinations than of
        nutrients.
    •   Other plant foods are broadly similar –
        fruit, vegetables, nut, legumes, spices
    •   Plant-based food patterns are more
        reliably ascertained epidemiologically and
        less prone to dietary confounding,
        inverse to many chronic diseases
    Nutrients vs Foods
Fiber is probably not as active as its
    accompanying phytochemicals
The value of carbohydrate depends on
    whether it is fiber rich (with
    accompanying phytochemicals) or
    fiber poor
The value of fat depends on saturation
    and location of the double bond if
    unsaturated
Some single nutrient conditions
•A single nutrient deficiency disease would be
alleviated by introduction of an isolated nutrient in
the form of a supplement
   – Scurvy and vitamin C
   – Pellagra, beri-beri and B-vitamins
   – Rickets and vitamin D
   – Neural tube defects and folate
   – Trans fatty acids, increased cholesterol and
     coronary heart disease
   – Hypertension and salt
Nutrition in the etiology of disease
•Focus on food and the synergy of its components
may be a method for better understanding
nutrition and disease etiology
  – Reductionism looks for simple, biochemically-based
    associations
  – Some diseases are the result of deficiency or excess of
    single nutrients
  – Food synergy is defined as additive or more than additive
    influences of foods and food constituents on health
  – Chronic diseases such as atherosclerosis, ischemic heart
    disease, and cancers, are complex with multiple etiologies
    and not simple deficiencies
The food synergy approach
A hierarchical structure of dietary patterns, foods, and nutrients for
study of food synergy.
“Top down” research begins with the higher levels, searching for
combinations of foods and their constituents that influence health
“Bottom up” research begins at the lowest level, searching for
individual constituents that influence health.
                        Examples of dietary component at each synergy level
  Food synergy level
  Level 5: Dietary      ‘Prudent diet’, ‘Western diet’, other combinations of
  pattern               food groups
  Level 4: Food         Whole grain, dairy, fruit, vegetables, meat
  groups
  Level 3: Whole        Whole wheat, brown rice, rolled oats
  grain
  Level 2: Whole        Bran, germ, endosperm; extract of fat soluble portion
  wheat
  Level 1: Bran or a   Specific nutrients or phytochemicals
  single phytochemical
Maximize nutritional value per bite
   • We are increasingly inactive
     – We are getting fat from positive
       energy balance
     – Even so, energy intake is less
       than it used to be
     – We cannot afford to waste bites
       eaten food with low nutritional
       value, such as nutrient-poor
       carbohydrate
     – Eat a varied diet rich in plant
       foods

				
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