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AN INVENTORY OF RANDOMIZED CONTROLLED TRIALS
USING PLANT-BASED DIETS
Clinical Evidence of Disease Reversal
November, 14 2014Micaela Karlsen, MSPH
www.PlantBasedResearch.org
Purpose
Evidence pointing towards effective clinical recommendations
Context in which to place individual studies
Grounding in evidence with which to engage in informed dialogue with colleagues
www.PlantBasedResearch.org
Hierarchy of Evidence
RCTs of DE
RCTs of Surrogate Endpoints
Prospective cohort studies
Retrospective cohort studies
Case-control
Cross-sectional
Case reports, anecdotal
DE = Disease Endpoints
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Decreasing bias, more ability to identify causal relationship
Plant-Based Nutrition Research, 1/1/10 - Present
Explosion of studies exploring plant-based / vegetarian diets
Only a portion look at chronic disease hard outcomes
Many cross-sectional surveysOnly two currently active
prospective cohortsSmall number of RCTsNumber of studies is
increasing!
www.PlantBasedResearch.org
Importance of the Big Picture
Totality of the evidence is more important than conclusions from one individual study
Analysis of the strength of evidence is informed by the methodological rigor of each study
Importance of understanding strengths & limitations of different study designs
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SUMMARY AND STRENGTH OF EVIDENCE
Inventory of Evidence
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Limitations
Study population belongs to specific religious group
Study population does not also include those eating high protein and/or high fat diets
Diet via FFQ assessed only once, at enrollment
7th Day Adventist Health Study IICurrent study is Adventist
Health Study-2 (AHS-2) is a health research study of 96,000 Seventh-day Adventists in the U.S. and Canada.
Primary goal is to study diet and cancer among a population at lower risk for all chronic disease
Follow-up every two years to track hospitalizations and diagnoses
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Limitations
May have some selection bias with more health-conscious vegetarians
Study population does not also include those eating high protein and/or high fat diets
EPIC Oxford CohortBegun in 1992, one of two EPIC
cohorts in the UKGoal: “…to recruit participants with
a wide range of diets by targeting vegetarians as well as participants from the general UK population. As such EPIC-Oxford is of great scientific value to the EPIC study as a whole, because the diets of vegetarians, and especially vegans, differ substantially from those of meat-eaters and this range in diets makes it easier to detect relationships between nutrition and health…”
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Inclusion Criteria in this Inventory
Overall inclusion criteria focus on WFPB dietary patterns, and studies whose results may be relevant to the discussion of WFPB diets
The diet was the main intervention (not single foods or nutrients)
The outcomes were markers of disease risk, disease endpoints, or relevant behavioral outcomes
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Timeline of Human Intervention Studies Targeting Plant-Based Nutrition
1950 1960 1970 1980 1990 2000 2010
* Single Arm Interventions
* Randomized Controlled Trials
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Inventory of RCTs – CVD & Risk Factors
Author Year
N Intervention diet
Outcomes Result Limitations
Ornish 1990 48 Vegetarian, <10% fat
Coronary atherosclerosis
82% of experimental-group patients had an average change towards regression of coronary atherosclerosis
Intervention includes other lifestyle changes
Gould 1995 35 Vegetarian, <10% fat
Myocardial perfusion abnormalities at baseline and 5 years after randomization
Improvement in perfusion abnormalities in intervention group vs. worsening in controls
Intervention includes other lifestyle changes
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Inventory of RCTs – CVD & Risk Factors
Author Year
N Intervention diet
Outcomes Result Limitations
Ornish 1998 48 (35 )
Vegetarian, <10% fat
5-year follow up: Adherence to intensive lifestyle changes, changes in coronary artery percent diameter stenosis, and cardiac events.
More regression of CA occurred after 5 years than after 1 year , CA continued to progress in control group
Intervention included other lifestyle changes
Colombo 2005 104 Vegetarian, low saturated fat
Decreased: Sat fat, arachidonic acid, ROMsIncreased: N-3, N-3/N-6 ratio
Improved blood lipid profile
Diet contained animal foods, outcomes beyond 18 weeks?
Medkova 2005 84 Vegetarian, includes milk
Blood lipids from drug response (athenolol or hypotiazide), with diet subgroups for each drug group
No difference in drug response, veg diet for both drugs had total and LDL improvement
Intervention involved drug treatmentwww.PlantBasedResearch.org
Inventory of RCTs – CVD & Risk Factors
Author Year
N Intervention diet
Outcomes Result Limitations
Barnard 2006 99 Low-fat, vegan Diabetes medication use, HbA(1c), body wt, LDL, urinary albumin among diabetics
Intervention diet had sig. benefits over Am. Diab. Assoc. diet
Outcomes beyond 22 weeks?
Elkan 2008 66 Gluten-free, vegan
Blood lipids & BMI among rheumatoid arthritis patients
Lower BMI, LDL and higher anti-PC IgM than control diet (p < 0.005).
Study population was RA patients
Ieromuzo 2012 42 Vegetarian, includes dairy
Blood lipids response among CAD patients on beta-blockers
Decreased blood pressure, total and LDL, increased HDL in vegetarian group
Intervention involved drug treatment
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Inventory of RCTs – T2D & Risk Factors
Author Year
N Intervention diet
Outcomes Result Limitations
Nicholson 1999 11 Low-fat, vegan
Glycemic and lipid control in patients with NIDDM
Reductions in fasting serum glucose concentration and body weight
Small sample size
Barnard 2009 99 Low-fat, vegan
Glycemic response, weight, and blood lipids
Vegan diet sig. lowered total and LDL cholesterol compared to Am. Diab. Assoc. diet,
Outcome after 74 weeks?
Kahleova 2011 74 Calorie-restricted vegetarian diet with and without exercise
Diabetes medication use, body wt, insulin sensitivity, subcutaneous and visceral fat
Intervention diet sig. benefit in all outcomes compared to control diet, diff. greater with exercise
Calorie restriction sustainable? Outcome after 24 weeks?
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Inventory of RCTs – T2D & Risk Factors
Author Year
N Intervention diet
Outcomes Result Limitations
Turner-McGrievy
2011 99 Low-fat, vegan Glycemic index load , wt loss, and HbA1c in T2D subjects
GI reduced more in vegan group, GL reduced more in conventional group. GI predicted changes in wt, wt loss predicted changes in HbA1c
Outcome after 22 weeks?
Kahleova 2013 74 Calorie-restricted, vegetarian
Changes in fatty acid composition of serum phospholipids in T2D subjects
Linoleic acid increased in vegetarian group but decreased in control group, neg. correlated with visceral fat
Calorie-restricted sustainable? Exercise in final 12 weeks. Outcome after 24 weeks?
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CVD, T2D & Risk Factors
Example of a strong study design: Barnard et al., 74 week intervention with T2D patients
Overall findings (8 studies): Vegan, low-fat diets resulted in stronger benefits on cardiometabolic risk factors and reversal of T2D & CVD
Overall limitations: Interventions including other lifestyle changes Duration of follow-up
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Inventory of RCTs on Cancer
Author Year
N Intervention diet
Primary Outcome
Result Limitations
Ornish 2001 93 Low-fat, soy-supplemented vegan diet
PSA among prostate cancer patients practicing surveillance
No adverse events after 1 year
Intervention included lifestyle components
Frattaroli 2008 93 Low-fat, soy-supplemented vegan diet
Clinical events among prostate cancer patients after 2 yrs follow up
Conventional treatment in (27%) control patients and (5%) experimental
Intervention included lifestyle components
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Cancer
Overall outcomes (1 study with follow up): Switching to a low-fat, vegan diet can help avoid or delay conventional prostate cancer treatment
Overall limitations: TOO FEW STUDIES (as with all of these topics) Interventions including other lifestyle changes Patient adherence Duration of follow-up
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Inventory of RCTs – Rheumatoid Arthritis & Fibromyalgia
Author Year
N Intervention diet
Outcomes Result Limitations
Kjeldsen-Kragh
1999 53 Fasting, gf vegan, vegetarian
Symptoms of rheumatoid arthritis in RA patients
Intervention group sig. improved
3 different treatments
Azad 2000 78 Vegetarian Pain & morbidity in fibromyalgia patients
Sig. but small improvement compared to drug therapy
Another arm w/o dairy?
Kaartinen * 2000 33 Vegan Fibromyalgia symptoms, total cholesterol, BMI
Improvement in all symptoms, wt loss, lower cholesterol
Non-randomized, small sample size
Agren 2001 29 Raw, vegan Blood lipids in RA patients
Vegan diet decreaseed total and LDL
Small sample size
Hafstrom 2001 66 Gluten-free, vegan
Levels of antibodies to food antigens in RA patients
Of diet completers, 40% vegan improvement, 4% control improvement
Low completion rate* Non-randomized,
controlledwww.PlantBasedResearch.org
Rheumatoid Arthritis & Fibromyalgia
Overall Findings (5 studies): Vegan diets produce improvement in symptoms
Overall limitations: Small sample sizes Which factors matter most? (Gluten-free, raw,
incorporating fasting) Short duration of follow up
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Inventory of RCTs on Nutrient Intake/Status
Author Year
N Intervention diet
Outcomes Result Limitations
Ruama 1993 43 Raw, vegan Nutrient intake among rheumatoid arthritis patients
Increase energy and micronutrient intake, 9% wt loss vegan group
Outcome beyond 3 months?
Turner-McGrievy
2004 59 Low-fat, vegan Nutrient intake per 1000 kcal in overweight women
Improved macro & micronutrient intake, except for food sources of D, B12, Ca, Se, P, Zn
Outcome beyond 14 weeks?
Dewell 2008 93 Low-fat, vegan Protective & pathogenic dietary factors among prostate cancer patients
Increased intake of protective factors after 1 year
Outcome beyond 1 year?
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Inventory of RCTs – Nutrient Intake/Status
Author Year
N Intervention diet
Primary Outcome
Result Limitations
Merrill 2009 119 Increased plant foods, reduce animal foods
Nutrient intake among men and women
Improved macro & micronutrient intake except Ca & D
More plant food, doesn’t eliminate animal food
Levin 2010 109 Low-fat, vegan Nutrient intake among overweight or T2D employees
Improved macro & micronutrient intake
Worksite setting, outcome beyond 22 weeks?
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Inventory of RCTs - Weight Loss
Author Year
N Intervention diet
Primary Outcome
Result Limitations
Turner-McGrievy
2004 59 Low-fat, vegan Nutrient intake per 1000 kcal
Improvements to all macro and micro intake, except vitamin D, vitamin B12, calcium, selenium, phosphorous, and zinc
Whole food sources vs. fortified or supplements
Turner-McGrievy
2007 62 Low-fat, vegan Wt & diet adherence at 1 & 2 yrs
Vegan diet and group support component predicted more wt loss
Women only
Burke 2008 176 Calorie-restricted, low-fat lacto-ovovegetarian diet
Effect of preference and diet prescribed
Only marginal improvement in blood lipids, participants assigned diet decreased triglycerides
Diet included animal food
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Nutrient Intake and Weight Loss
Overall outcomes (7 studies): Low-fat, vegan diets produce improvements in nutrient
intake. Low-fat, vegan diet assist in healthy weight loss. Attention to micronutrient intake may be required for
optimal dietary quality.
Overall limitations: Duration of follow-up was short for long-term weight
maintenance Which matters most? (Vegan vs. vegetarian vs.
improving dietary quality)
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Inventory of RCTs – Acceptability of Plant-Based Diets
Author
Year N Intervention diet
Outcomes Result Limitations
Barnard 2004 64 Low-fat, vegan
Acceptability, ease of continuation, dietary restraint, disinhibition, hunger
Comparable acceptability to Nat. Cholest. Ed. diet
Outcomes after 14 weeks?
Barnard 2009 99 Low-fat, vegan
Disinhibition, hunger, cravings for fatty foods, ease of prep
Comparable acceptability to Am. Diab. Assoc. diet, except slightly for ease of prep
Outcomes after 74 weeks?
Hyder 2009 2254
Increased fruit, veg, fiber, & lower fat
More plant-based diet had increased cost of $1.22/ person/week
Increased cost was minimal
Diet still contained meat and dairy
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Author
Year N Intervention diet
Outcomes Result Limitations
Katcher 2010 113 Low-fat, vegan
Greater mental health, vitality, lower food costs, more difficulty finding food out
Overall higher diet satisfaction compared to control
Worksite wellness program – generalizability?
Lazor 2010 5 schools
15 soyfoods in place of meat items in middle school lunch
Plate waste and ratings of new foods from students
Same amount of soy-based and traditional patties, nuggets, and pasta, and less soy than regular chicken in the salad
Foods tested were meat analogues, not whole plant foods
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Inventory of RCTs – Acceptability of Plant-Based Diets
Acceptability of Plant-Based Diets
Overall Findings (5 studies): Plant-based diets may be equivalently or better
tolerated than meat-containing diets Increase in cost for increased F&V is minimal
Overall limitations: Impact of cooking skills, time, economic resources Whole plant foods vs. meat analogues or transition
foods Need cost analyses of 100% WFPB diets, not just
increased plant food diets
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Download Page for References
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http://plantbasedresearch.org/ppod
Conclusions
Evidence base does exist to make clinical dietary recommendations to use plant-based nutrition
Plant-based diets are safe, effective, and enjoyable
Patients may need substantial training and support for transition
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