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How does science prove that a food is healthy?

Martijn B. Katan Department of Health Sciences

VU University Amsterdam www.mkatan.nl

KNAW Symposium 'What is scientific evidence for nutrition and health claims' Amsterdam, 26 March 2011

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Competing interests • 1986 – 2001:

Grants and materials from Unilever, Nestlé, dairy, coffee and other food industries

• At present: Income from columns and book. No consultancies, speaker fees, stocks etc.

Outline

1. Health claims for foods 2. How can we prove that a food is healthy? 3. The controversy between EFSA and industry 4. A crisis of confidence, and what to do about it

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How did this meeting arise?

• Probiotics are ‘beneficial’ microbes • Probiotic researchers claim that probiotics

promote gut health and resistance • EFSA considers these claims unproven • ‘Can KNAW discuss how one proves that a

food or food component is healthy?’ 4

Why probiotics are big business

• Patentable

• Huge sales (Actimel 2006: €1,400,000,000) • Large profit margin: Yakult costs €4.79 per

litre, regular yoghurt €0.75

Katan MB. Beneficial Microbes 2012, in press

Healthy components healthy food? • Vitamin D is healthy

“the Panel [EFSA] concludes that a cause and effect relationship has been established between the intake of vitamin D and a reduction in the risk of falling”.

• Is a candy bar with vitamin D healthy?

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Ingredients: Rolled Oats, Sugar, Cream (from Milk), Skim Milk, Inulin (Chicory Root Fiber), Soy Protein Crisp (Soy Protein Isolate, Tapioca Starch, Soybean Fiber, Salt), Chocolate, Canola Oil, Calcium Phosphate, Brown Rice Syrup, Oat Flour, Molasses, Cocoa Butter, Palm Kernel Oil, Honey, Salt, Cocoa Powder, Soy Lecithin, Natural Flavor, Palm Oil, Vitamin D3. Kraft MilkBite Granola Bar

Nutrient profiling: a scoring system to add up good and bad ingredients

• Health claims: can a candy bar claim to prevent falls?

• TV advertising to children: which foods to prohibit?

• Health logo: which foods get it?

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Outline

1. Health claims for foods 2. How can we prove that a food is healthy? 3. The controversy between EFSA and industry 4. A crisis of confidence, and what to do about it

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Research approaches in nutrition and health Type Major Strength Major limitation

Mechanistic Insights Extrapolation Animal trials Hard end points Extrapolation Epidemiology Hard end points Confounding

Biomarker trials Human; controlled Validity of biomarker Clinical trials Hard end points Duration

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Research approaches in nutrition and health

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Type Major Strength Major limitation Mechanistic Insights Extrapolation

Animal trials Hard end points Extrapolation Epidemiology Hard end points Confounding Biomarker trials Human; controlled Validity of biomarker Clinical trials Hard end points Duration

The problem with mechanistic arguments

“…our understanding of biologic mechanisms remains far too incomplete to predict confidently the ultimate consequences of eating a particular food or nutrient…” (Willett)

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Research approaches in nutrition and health Type Major Strength Major limitation

Mechanistic Insights Extrapolation Animal trials Hard end points Extrapolation Epidemiology Hard end points Confounding

Biomarker trials Human; controlled Validity of biomarker Clinical trials Hard end points Duration

Are animal trials useful in nutrition?

• Not useful to decide IF something works • Useful to find out HOW something works

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Research approaches in nutrition and health

Type Major Strength Major limitation Mechanistic Insights Extrapolation Animal trials Hard end points Extrapolation Epidemiology Hard end points Confounding

Biomarker trials Human; controlled Validity of biomarker Clinical trials Hard end points Duration

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The pro’s and cons of epidemiology

• Real people, real disease, long term • Confounding ✔ ✗

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Educated, lean, nonsmoking, exercise, the right doctor, healthy job, good neigborhood, moderate alcohol, fish, vegetables, wholewheat bread, low-fat milk, vitamin pills

Nutritional epidemiology’s problem Residual or unmeasured confounding

Unschooled, obese, smokes, no exercise, wrong doctor, factory job, poor neigborhood, no alcohol, pork chops, french fries, white bread, cola

The pro’s and cons of epidemiology

• Strong relations between a nutrient or food and a disease suggest causality

• Weak relations may be due to confounding

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Placebo

Experiment eliminates confounding

Probiotic

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Research approaches in nutrition and health

Type Major Strength Major limitation Mechanistic Insights Extrapolation Animal trials Hard end points Extrapolation Epidemiology Hard end points Confounding

Biomarker trials Human; controlled Validity of biomarker Clinical trials Hard end points Duration

A biomarker is a surrogate for a disease High blood pressure − stroke Low bone density − fracture White blood cells − infection

Pro’s and cons of biomarker trials

– Experiment causality – Done in humans – Requires 10 to 100 subjects and 4-8 weeks

– Relation of biomarker with disease is never 100% – Often requires leap of faith

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✔

✔

✗ ✗

✔

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Research approaches in nutrition and health Type Major Strength Major limitation

Mechanistic Insights Extrapolation Animal trials Hard end points Extrapolation Epidemiology Hard end points Confounding

Biomarker trials Human; controlled Validity of biomarker Clinical trials Hard end points Duration

Volunteers eat ‘healthy’ food or control food Observe which group gets less disease

Pro’s and cons of Randomized Clinical Trials

– Prove causality – Show effect on disease in humans – ‘Failed’ studies cannot be swept under the carpet

– Expensive – Trial may not last long enough to show effect

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?

✔ ✔ ✔

✗ ✗

Research approaches: conclusions

• It is hard to prove that a food or nutrient is healthy, but not impossible

• Nutrition science has discovered many important health effects of foods an nutrients in the past decades

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Katan MB, Eur J Clin Nutr 2009

Outline

1. Health claims for foods 2. How can we prove that a food is healthy? 3. The controversy between EFSA and industry 4. A crisis of confidence, and what to do about it

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Why the controversy between EFSA and the food industry over ‘proof’?

1. Scientific proof versus legal proof 2. The credibility crisis

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Scientists and lawyers play by different rules

• Scientist: truth exists. Let’s go and find it!

• Lawyer: fight to win. Leave ‘truth’ to the judge!

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Probiotics firms speak ‘legalese’, EFSA speaks ‘scientese’

• Probiotics company: What are the rules for a claim ‘softer stools’?

• EFSA: You know as well as we do.

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Scientific proof versus legal proof

• Probiotic firms want rules and algorithms that will predictably guide them to a health claim

• EFSA says: scientific discovery does not come out of a cookbook

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Outline

1. Health claims for foods 2. How can we prove that a food is healthy? 3. The controversy between EFSA and industry 4. A crisis of confidence, and what to do about it

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Nutrition science faces a credibility crisis

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Does EFSA trust industrially funded science? Does anyone trust industrially funded science?

The big issue: trust

Would you buy a second-hand car from … •A politician? •A nutrition professor? •Any professor?

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How many Dutch people have trust in various sources of health information? • 85% trust health professionals • 68% trust scientists • 30% trust the media • 25% trust the internet

But 60% of the Dutch totally agree that:

‘We can no longer trust scientists … because they depend more and more on money from industry’

32 CPB. Kwartaalbericht 2010-2; Eurobarometer 2010, #287 and 73.1;

The loss of trust in science forms a threat to the health and wellbeing

of society

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What caused the credibility crisis in nutrition?

Marktism -- the belief that the free market is the answer to all society’s problems

•The need to obtain industry funding makes it hard for scientists to state unpleasant truths •Industry-funded research may yield biased outcomes

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Lesser, PLoS Medicine 2007

The bigger picture

Wrangling over nutrition claims is part of a bigger problem:

erosion of trust in science

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What to do? How to regain public trust in nutrition scientists

– Abolish industry-funded nutrition research in universities

– Exclude industry-funded researchers from giving scientific advice

Thank you for your attention!

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