Isoflavones: What do Isoflavones: What do Users Want/Need to Users Want/Need to Know?Know?

Leila G Saldanha, PhD, RDLeila G Saldanha, PhD, RDPresident, NutrIQ LLCPresident, NutrIQ LLCAlexandria, VA, USAAlexandria, VA, USA

Outline of Talk

Users:• Researchers• Health Practioners (dietitians) &

Consumers

ResearchersResearchers

Soy: AHRQ Review

Evidence Report: Effects of Soy on Health Outcomes

Tufts-New England Medical Center

Evidence-based Practice Center, Boston, MA

Joseph Lau, MD, Director

Identify relevant studies Identify relevant studies that meet search criteriathat meet search criteria

NONONot useful for review or to draw scientific conclusions

Systematic ReviewSystematic Review

Evidence useful for drawing conclusions to queries.

Analytical scheme for rating & ranking studies

YESYES

Report Findings

Application of Systematic Application of Systematic Reviews:Reviews:

•• Develop practice Develop practice guidelines.guidelines.

•• Determine research Determine research needs.needs.

•• Policy recommendations.Policy recommendations.

•• Approval of health claims.Approval of health claims.

Principal Key Question

• Is there clinical trial evidence to indicate that whole soy products and individual constituents of soy have an effect on a variety of health conditions and disease states, and risk-factors for these states:

• Also considered: what formulations of soy were used and dose response on effects.

•• 47794779 abstracts screened, 178178 articles included in final review.

Wide variety/dose of soy products:• Soy protein with/without isoflavones.• Soy protein with ??isoflavones; soy

isoflavones alone.• Incorporated into diet or as a supplement.• Soy protein dose: 0-154 g/day; median 36

g/day.• Soy isoflavone dose: 0-185 mg/day.

Literature Search Results(December 2004)

Results – Overall

• Small benefit (~ 5%) on LDL and triglycerides levels.• Possible dose effect of soy protein, not clear if

isoflavone mediated.• Possible increased benefit in those with higher

baseline levels.• Possible benefit of soy isoflavones for post-

menopausal symptoms.• No consistent evidence of effect on other

outcomes.

Some Limitations

• Large heterogeneity in soy products tested, protein doses, isoflavone content, mode of incorporating into diets, controls used, study duration, outcome measurements.

• >50% studies were of poor quality.• No evaluation of other possibly active

constituents.• Very few studies of “reasonable” doses.

• Median soy protein dose equivalent to 1 lb tofu or 3 protein shakes daily.

Other Issues – Reported by Researchers

• Variability in the isoflavone content of animal diet. This variability is not only diet-to-diet but batch to batch.

• Variation in the isoflavone content of animal diets are affecting results of experiments.

• The variability in the isoflavone content in animal diets makes it difficult to replicate results across laboratories.

• Unlabeled isoflavone content in prepared foods for human consumption.

Selection of Test Materials Used in Research: What is the “substance”?

Whole Food?Whole Food?Isolated Active Isolated Active Components?Components?

OROR

• Paradox with clinical trials - many well designed trials with poorly characterized materials.

• Cannot attribute causality.

Guidance for Researchers.

• Provide clear and complete descriptions of intervention.• Characteristics of herbal products; part(s) of plant,

extraction process.• Dosage regimen.• Purity: qualitative and quantitative testing.• Standardization.•• Placebo or control productPlacebo or control product.

• Reporting Randomized, Controlled Trials of Herbal Interventions: An Elaborated CONSORT Statement. Annals of Internal Medicine 2006 144:364-367. http://www.consort-statement.org/

• Biologically Active Agents Used in CAM and Placebo Materials--Policy and Guidance. http://nccam.nih.gov/research/policies/bioactive.htm

Consumers & Consumers & Health PractionersHealth Practioners

What they said.

• Be able to compare products on the store shelves --- what to buy.

• How much should they consume to derive health benefits.

• Information on proven health benefits.

Closing Thoughts - Suggestions

• Uniform approach for reporting information in consumer and scientific literature: nomenclature system, units of measure, etc…..

• Write white-paper on isoflavone products: How should they be characterized and reported in publications.

Leila G SaldanhaLeila G Saldanhalgs@nutriqlgs@nutriq--llc.comllc.com

Phone:202Phone:202--460460--35293529Fax: 703Fax: 703--317317--92539253