Has nutrition research helped us with our food choices?

Simon Thornley (Epidemiologist)University of Auckland

Summary What is science/epidemiology? A brief history of human nutrition I get involved… diversion into tobacco Food addiction? What next?

My view Yes, but many nutrition scientists are not

listening to the data Fructose, sugar, carbohydrates are often

overlooked

What is science or research?

“In God we trust, all others bring data” William Edward Deming

“First establish the facts, then seek to explain them”

Aristotle

Science Anarchistic; consensus not useful Hypothesis and argument Disproof over proof Uncertainty over absolutes Integration

A basic epidemiological study…

Disease

What we eat

Subjects

Focus on statistical over biological evidence…

Error… Many contradictory studies

Error

RandomSystematic

False +ve~5%

False –ve~10 to 20%

Selection biasrecruitment %

Information bias

Accuracy of measures?

Unmeasured confoundingRCT? From literature?

Accounted for by 95% confidence interval and p-value

Not included in CI or p-value [Quantitative bias analysis]

Confounding…

Dental cariesCoronary Heart

Disease

Sugar consumption

Bradford-Hill Criteria

Strong association? Consistent? Does cause come

before effect? More

exposuremore disease?

RCT better than observational study

Makes sense

Salt restriction Salt restriction ↓ blood pressure Observational studies show both ↑ and ↓

survival (unmeasured confounding) Only randomised study shows benefit in

group that didn’t restrict salt.

Taylor, R. S., Ashton K. E., T. Moxham, L Hooper, and S. Ebrahim. "Reduced Dietary Salt for the Prevention of Cardiovascular Disease." Cochrane Database of Systematic Reviews, no. 7 (2011). http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD009217/

frame.html.

HOW DOES SCIENCE GO WRONG?

Is the idea falsifiable?

How it works in theory…

IdeaGenerate

hypothesis

ExperimentTest

hypothesis

InterpretInferences from

experiment

New IdeaRefine

hypothesis

In reality…?

IdeaGenerate

hypothesis

ExperimentTest

hypothesis

InterpretInferences from

experiment

New IdeaRefine

hypothesis

NUTRITION IDEAS OVER THE LAST 100 YEARS…

Some history…

Museum photo…

Dairy photo

What happened in the 1960s? Diet-heart hypothesis Heart disease caused by saturated fat Response: reduce fat (↑sugar or carb.) Cheap sugar (HFCS in USA) American Heart Assoc other English

speaking countriesTaubes G. The Diet Delusion. New York: Vermilion; 2007.

THE ACCEPTED STORYBrain washing?

Nutrition to the rescue…

A – B = CA = Energy in (food)B = Energy out (burned, metabolism)C = Energy stored (as fat)

Cause↑A/↓B→↑C – obesigenic environment (↑energy in/ reduced energy out)

THE GOOD!What’s ok...

THE BADIt’s not OK... Ever!

http://longwhitekid.files.wordpress.com/2011/08/anchor-best-new-zealand-butter-380h-x-270w-heavy-card-21.jpg

Salt

WE ALL LIVED HAPPILY EVER AFTER?

Year

Ob

esi

ty p

reva

len

ce (

% >

= b

od

y m

ass

ind

ex

30

kg

/ m

2 )

10

20

30

1980 1990 2000

Australia Austria

1980 1990 2000

Belgium Canada

1980 1990 2000

Czech Republic Denmark

Finland France Germany Hungary Iceland

10

20

30

Ireland

10

20

30

Italy Japan Korea Luxembourg Mexico Netherlands

New Zealand Norway Poland Portugal Slovak Republic

10

20

30

Spain

10

20

30

Sweden

1980 1990 2000

Switzerland United Kingdom

1980 1990 2000

United States

AN ALTERNATIVE VIEW EMERGES…

My thoughts on obesity…

Medical trainingTraditional Nutritional theory - Energy density

Public HealthTobacco addiction

ResearchSimilarities between obesity and smoking

ResearchCritique of energy densityFocus on sugar

1994 2005 2007 2011

Why does a smoker smoke?

WithdrawalSymptoms Duration (weeks)

Irritability < 4

Depression < 4

Restlessness < 4

Poor concentration <2

Increased appetite >10

Craving to smoke >2

Automatic behaviour

Rational behaviour

Addiction Automatic,

withdrawal, harm

Automatic breathing

CortexMid brain/brain stem

Subconscious learning…

Withdrawaldiscomfort

Puffcigarette

WithdrawalreliefMore

puffs

Nicotine metabolised

How do cigarettes work...?

Nicotine delivery

Royal College of Physicians, Nicotine in Britain, 2000

FOOD ADDICTION?

Carbohydrate?

Eating and addiction? Atkins Diet An executive who had tried obesity surgery,

laxatives, diets, everything…

“Often I would shake until I could put some sugar in my mouth”

“I had an hour’s drive from my office to my home, and I knew every restaurant, candy machine and soft drink dispenser”

What about glucose? Is refined starch the same as nicotine? Are low GI foods the obese person’s

equivalent to a smoker’s nicotine patch or gum?

Bread: white v. wholegrain

Glucose: glycemic index?

What about sugar? Sugar is actually low/moderate GI

I TAKE A LOOK AT SUGAR?

The medical gurus say sugar is OK? “Excess sucrose has largely been

exonerated as an important dietary factor in the aetiology of type-2 diabetes...”

J. I. Mann and A. S. Truswell

Diseases of overnourished societies and the need for dietary change: in the Oxford Textbook of Medicine, 4th Edition.

Postprandial glycemia (GI) used to exonnerate sugar…

Sugar: traditional views 30% increase over last 30 yearsPopkin BM, Nielsen SJ. The sweetening of the world's diet. Obesity Research 2003;11(11):1325-32.

“Empty calorie”Nestle M. Soft drink "pouring rights": marketing empty calories to children. Public Health Reports

2000;115(4):308-19.

Fructose not mentioned

Something is missing?

Update... AHA turns around. “Fructose... has been indirectly implicated

in the epidemics of obesity and type 2 diabetes”

Circulation 2009;120;1011-1020

Fructose: what has changed? GI ignores fructose Sweeter than glucose Linked to:

Gout, diabetes, weight gain, metabolic syndrome Hypertension, rotten teeth High triglycerides, dyslipidaemia, CVD

Tends to ↑ hungerJohnson, R.J., et al., Hypothesis: Could Excessive Fructose Intake and Uric Acid Cause Type 2 Diabetes? Endocr Rev, 2009. 30(1): p. 96-116.

Segal, M.S., E. Gollub, and R.J. Johnson, Is the fructose index more relevant with regards to cardiovascular disease than the glycemic index? European Journal of Nutrition, 2007. 46(7): p. 406-17.

What about saturated fat? Recent summaries

no association with heart disease.

Skeaff CM, Miller J. Dietary Fat and Coronary Heart Disease: Summary of Evidence from Prospective Cohort and Randomised Controlled Trials. Ann Nutr Metab 2009;55:173–201

Mente A, de Koning L, Shannon HS, Anand SS (April 2009). A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch. Intern. Med. 169 (7): 659–69.

Food addiction: evidence Addiction pathways Eating is automatic Rats

sugar induces withdrawal; not fat.

In the headlines…

My inbox... “For three weeks I cut all sugar and

flour… then…

mood swings…, depression…, stomach pain…, joint and muscle pain…, the shakes….”

“People who knew me started thinking I was hiding a drug problem.”

Overeater’s Anonymous “When you are addicted to drugs you put

the tiger in the cage to recover; When you are addicted to food, you put the

tiger in the cage, but take it out three times for a walk”

Kerri-Lynn Murphy Kriz

Critique: Academia “Any addictive … hypothesis can't explain

the rise that we've seen over the last … 30 years of obesity.”

Prof. Boyd Swinburn, Professor of Population Health, Deakin University 13 Jan 2009

SO WHAT?

Synopsis Nutrition focuses on energy not hunger Low fat idea predates obesity epidemic Sugar intake continues to ↑ Likely subtle addiction Likely cause of major risk factors for heart

disease Many nutrition researchers stuck in

energy paradigm (cf. some pop science)

More details

Thank you!

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