Transcript Let`s go green

diet-related controversies
in cardiovascular disease
Dr Rosemary Stanton OAM
controversies?
 blood cholesterol - how important?
 saturated fats - are they now ‘good’?
 vegetable oils - are they ‘toxic’?
 sugar & carbohydrates – are they the real
culprits?
© Rosemary Stanton 2014
why the controversy?
 misinterpretation of scientific papers
 media pick-up of studies (scientific journals
now seek publicity)
 cherry-picking study results
 self-styled ‘experts’, popular books, blogs, TV
programs
 favouring nutrients over foods
© Rosemary Stanton 2014
misinterpretation
made easy because
– dietary studies give ‘gross’ results, usually a limited
range of foods, making interpretation difficult
– diets are often categorised on the basis of broad
terms such as ‘carbohydrate’ or ‘saturated,
monounsaturated or polyunsaturated fat’
© Rosemary Stanton 2014
saturated fat
the same quantity of saturated fat in
- a tablespoon of lard
- 35g of cheddar cheese
- 35g of white chocolate
- a small piece of rump steak (145g)
- 70g of potato crisps
- 90g roasted cashews
- 50g of polyunsaturated margarine
- a small custard tart
- 15g hollandaise sauce
© Rosemary Stanton 2014
monosaturated fat
is the dominant type of fat in
- chicken noodle soup powder
- peanut & olive oils
- eggs
- almonds
- avocado
- licorice
- rolled oats
- chocolate chip muesli bars
- chicken nuggets
© Rosemary Stanton 2014
polyunsaturated fat
which ones do we mean
- omega 6 (presumably linoleic acid)
- omega 3s
- alpha linolenic acid?
- EPA, DPA, DHA?
and which food sources?
- omega 6 oils not consumed on their own
- omega 3s in plants, seafood, grass-fed meat
© Rosemary Stanton 2014
polyunsaturated fat
different levels in foods
- omega 3s present in milligrams
- omega 6s present in grams
© Rosemary Stanton 2014
carbohydrates
which ones
- sugars (refined or natural sugars in fruit, milk?)
- starches
- refined?
- with or without dietary fibre, protein, fat?
and which food sources?
© Rosemary Stanton 2014
carbohydrate
food sources vary
- rolled oats
- wheat or flour (stoneground or recombined)
- rice
- fruit
- potatoes
- peas
- jelly beans & confectionary
- apple pie
- sugar-sweetened drinks
- processed sugary cereals
- tomato sauce
© Rosemary Stanton 2014
misinterpretation
 considering nutrients rather than their food
sources produces gross distortions &
misinterpretation
 Dietary Guidelines (2013) now in terms of
foods rather than nutrients
 the processed food industry continues to
prefer to discuss nutrients rather than foods
© Rosemary Stanton 2014
media pick-up
 journalists rarely search medical/scientific
journals
 journals, conferences, publishers issue media
releases & chase coverage
 those with products to sell engage public
relations people to get media coverage
 media feed off each other (eg radio usually
follows newspapers)
 mainly interested in anything ‘new’ or
‘controversial’
© Rosemary Stanton 2014
cherry-picking
 ‘expert’ authors cherry-pick studies that suit
their argument
 those with a product to sell (including a book)
are especially likely to cherry-pick
© Rosemary Stanton 2014
controversy over cholesterol
two aspects – both widely promoted
– statins
– dietary theories & products
© Rosemary Stanton 2014
controversy over cholesterol
statins
– widely prescribed & expensive
– may be prescribed because ‘lifestyle advice’
to lower blood cholesterol is too difficult
– possible conflicts of interest between
promotion and pharmaceutical companies
© Rosemary Stanton 2014
controversy over cholesterol
Dr Aseem Malhotra, cardiology registrar,
claimed that advice to reduce cholesterol “has,
paradoxically, increased our cardiovascular
risks”
and
“saturated fat is not the major issue for
cardiovascular disease”.
Malhotra A. Observations. Saturated fat is not the major issue. BMJ. 2013;347
http://www.bmj.com/content/347/bmj.f6340
© Rosemary Stanton 2014
controversy over cholesterol
Catalyst programs* generated great confusion
- used ‘experts’ who market a range of
alternative products, including diets and
cholesterol-lowering supplements
- generated further publicity from popular diet
book authors who pushed Catalyst’s line that
reductions in saturated fat had increased
cardiovascular disease
http://www.abc.net.au/catalyst/stories/3876219.htm#comments
© Rosemary Stanton 2014
saturated fat
questions
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has consumption changed?
is there really new evidence?
are the Dietary Guidelines wrong?
are all saturated fatty acids equal?
is it OK to promote fatty meat, more butter,
cheese, coconut oil?
© Rosemary Stanton 2014
saturated fat
consumption
– evidence of a slight decrease in the US
– accompanied by increase in energy intake*
– increased energy is from sugars & refined
starches
*Trends in Intake of Energy and Macronutrients - United States, 1971—2000.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5304a3.htm
© Rosemary Stanton 2014
saturated fat – new evidence?
– ‘evidence’ from analyses claims that saturated fat is
not a problem*,**
– this has been strongly contested***
– saturated fat foods not the only dietary problem
– saturated fatty acids not equally problematic
*Siri-Tarino PW, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of
saturated fat with cardiovascular disease. Am J Clin Nutr. 2010; 91(3):535-46
** Chowdhury R et al. Association of dietary, circulating and supplement fatty acids with coronary risk: a
systematic review and meta analysis. Ann Intern Med. 2014;160(6):398-406
*** Stamler J. Diet-heart: a problematic revisit. Am J Clin Nutr. 2010; 91(3):497-99
© Rosemary Stanton 2014
saturated fatty acids
not equal
– palmitic & myristic acids (two commonly
consumed saturated fats) contribute to
inflammation, elevated lipids, atherogenesis &
vascular disease
– lauric acid may increase HDL as well as LDL
© Rosemary Stanton 2014
saturated fat & Dietary Guidelines
have recommended less saturated fat
– did not recommend trans fats
– did not recommend replacing saturated fat
with sugary foods
– did recommend more fruits, vegetables,
wholegrains
– were rarely followed*
* Ball K, Mishra GD, Thane CW, Hodge A. How well do Australian women comply with dietary
guidelines? Public Health Nutr. 2004;7(3):443-52.
© Rosemary Stanton 2014
saturated fat & 2103 Guidelines
– changed focus to foods
– evidence against foods high in saturated fats
remains
– strengthened advice on discretionary foods
(which provide saturated fat & sugar)
– stronger recommendations for plant foods fruits, vegetables, wholegrains, legumes, nuts
© Rosemary Stanton 2014
saturated fatty acids
foods high in saturated fat
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no evidence of need or benefits from sat. fat
coconut oil not ideal*
milk, cheese, yoghurt different from butter
meat fat: “convincing evidence that processed
& fresh meats are causes of colorectal
cancer”**
* Cox C et al. Effects of coconut oil, butter and safflower oil on lipids and lipoproteins in persons
with moderately elevated cholesterol levels. J Lipid Res. 1995;36:1787-95.
**www.wcrf.org/cancer_research/cup/key.../colorectal_cancer.php
© Rosemary Stanton 2014
saturated fatty acids
real problems
– a single nutrient biomarker is insufficient
evidence to assess cardiovascular risk*
– suitable substitutes
– best substitute is a liquid oil
– problem mainly for processed food industry
– Australians need to reduce kilojoules
*Astrup et al. The role of reducing intakes of saturated fat in the prevention of cardiovascular
disease: where does the evidence stand in 2010? Am J Clin Nutr 2011;93(4):684-8
© Rosemary Stanton 2014
vegetable oils
are they toxic?
– no evidence of toxicity for liquid oils*
– problems when oils are used in processed
foods due to hydrogenation (saturated fat) or
partial hydrogenation (trans fat - elaidic acid)
*Mozaffarian D1, Micha R, Wallace S. Effects on coronary heart disease of increasing
polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of
randomized controlled trials. PLoS Med. 2010 Mar 23;7(3):e1000252.
© Rosemary Stanton 2014
fish oils
are they beneficial?
– yes, for reducing triglycerides*
– no, for reducing the risk of cardiovascular
disease**, ***
– yes, if consumed from fish/seafood
*Rizos EC. Ntzani EE. n-3 fatty acids and lutein + zeaxanthin supplements for the prevention of
cardiovascular disease. JAMA Intern Med. online March 17, 2014.
doi:10.1001/jamainternmed.2013.13734
**AREDS2 Research Group. Effect of long-chain n-3 fatty acids and lutein + zeaxanthin
supplements on cardiovascular outcomes. JAMA Intern Med. online March 17, 2014.
doi:10.1001/jamainternmed.2014.328.
*** Chowdhury R et al. Association of dietary, circulating and supplement fatty acids with
coronary risk: a systematic review and meta analysis. Ann Intern Med. 2014;160(6):398-406
© Rosemary Stanton 2014
where to from here?
foods ?
or
nutrients ?
or
style of eating ?
© Rosemary Stanton 2014
lesson from research
consider whole foods & whole diets- e.g.
– olive oil is not just monounsaturated fat
(has many other components)
– olive oil encourages vegetable consumption
– vegetable consumption changes eating style
© Rosemary Stanton 2014
components of EVO
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simple phenols (tyrosol, hydroxytyrosol)
terpenes (oleuropein, ligstroside)
flavones (apigenin, luteolin)
hydroxycinnamic acids (caffeic acid, cinnamic acid,
ferulic acid, coumaric acid)
anthocyanidins (cyanidins, peonidins)
flavonols (quercetin, kaempferol)
flavonoid glycosides (rutin)
lignans (pinoresinol)
hydroxybenzoic acids (vanillic acid, syringic acid)
© Rosemary Stanton 2014
modern Western diets
promote
- obesity
- type 2 diabetes
- cardiovascular disease
- some cancers (colon, breast, prostate)
© Rosemary Stanton 2014
modern Western diets
emphasise
- foods & drinks high in added fat, sugar, salt
- highly processed grains
- meat dominates plate (if there is one!)
- vegetables – missing or just chips
- fruit juice preferred to fruit
- dairy (milk, cheese, yoghurt, ice cream)
- alcohol (with or without food)
© Rosemary Stanton 2014
modern Western diets
low in
– vegetables & legumes
– fruit
– nuts
– wholegrains
© Rosemary Stanton 2014
Mediterranean diets
observational studies
many studies show value in Mediterranean diets
for CVD, depression, longevity (even among
those who are overweight)
1° prevention trial (Predimed trial*)
Med diet + EVO or Med diet + nuts
* Estruch R, Ros E, Salas-Salvado J, et al. Primary prevention of cardiovascular disease with a
Mediterranean diet. N Engl J Med 2013;368:1279-1290
© Rosemary Stanton 2014
Mediterranean diets
emphasise
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fresh foods
vegetables, legumes, herbs
olive oil
fruit
grains, mostly traditional bread
nuts
dairy (mainly cheese & yoghurt)
seafood
red wine (small quantities with meals)
© Rosemary Stanton 2014
Mediterranean diets
low in
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red meat
milk
butter, margarine
processed foods
fast foods
© Rosemary Stanton 2014
style of eating
considerations
– meals spaced to permit hunger?
– are modern snacks appropriate?
– eating with others (family meals?)
© Rosemary Stanton 2014
the balanced diet
nutrition
& health
environmental
sustainability
taste
‘food literacy’
© Rosemary Stanton 2014