Download Superfoods

Superfoods
Catherine Collins RD FBDA
Principal Dietitian
St Georges Hospital NHS Trust
To be covered:
Superfoods vs whole diet approach
| Definition of a ‘superfood’
| Potential benefits of superfood
constituents
| Limitations of research vs food-based
diet
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Food classification
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By nutrient content:
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By ability to prevent disease:
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Protein
Type of fat
Iron rich foods to correct anaemia
Vitamin D to prevent rickets
By non-nutritive functional content:
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Prebiotic fibres for gut bacteria
Plant phytochemicals as anti-oxidants
Food classification
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‘Cultural’ superfoods:
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‘Prestige’ foods:
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Tridosha
Yin-yang
Galenic humoral
‘Sympathetic magic’ foods:
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Difficult to obtain
Often protein based
‘Body image’ foods:
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Dominant staple / source of calories / essential
Pomegranate
Walnut
Eggs
‘Physiological’ food groups
Derrick Jelliffe; AJCN 1967
The ‘Mediterranean Diet’
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Dr Ancel Keys 1904 - 2004
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Physiologist at the University
of Minnesota
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Director of the ‘Seven
Countries Collaborative Study’
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Dietary principles ratified in
subsequent research of over
450 clinical papers…..
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12 studies addressing ‘Mediterranean Diet’
1,574,299 subjects followed for 3-18 years
… of which eight cohorts (514,816 subjects, 33,576 g)
9% reduction in overall mortality
9% reduction in death from cardiovascular disease
6% reduction in risk of cancer, or dying from cancer
13% reduction in risk of Parkinson’s disease and
Alzheimer’s disease
Sofi et al: BMJ 2008
Risk of developing, or dying from cancer:
Risk of dying from heart disease:
Benefits of diet and lifestyle change:
middle age
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15,792 men and women aged 45 to 64, part of the
Atherosclerosis Risk in Communities (ARIC) Study
970 (8.4%) newly adopted a healthy lifestyle:
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at least 5 fruits and vegetables daily
at least 2.5 hours per week of exercise
maintain BMI between 18.5 – 30
stopped smoking
OR
95% CI
Heart attack or stroke
0.65
0.39-0.92
All cause mortality
0.60
0.39-0.92
King et al; American Journal of Medicine 2007
Nutrition and health:
quality of evidence
Mediterranean diet
‘Superfoods’
Early nutrition research:
the ‘ positive reductionist’ approach
James Lind
| Performed randomised controlled dietary trial
| Citrus fruits prevented scorbutic lesions (1753)
| 1794 – lime juice regularly given to sailors
| 1912 – chemical structure of Vitamin C identified
Takaki Kanehiro
| Identified poor diet as a cause of beri-beri (1884)
| View against prevailing opinion that beri-beri was
an infectious disease
| 1910 - Umetaro Suzuki identifies chemical structure
| Eijkman identifies B1 and wins 1929 Nobel prize
Recent nutrition research:
the ‘negative reductionist’ approach
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22 randomized controlled trials, 161,045 subjects
88,610 in antioxidant supplement groups vs
72,435 in placebo or no-intervention groups
no preventive effect on cancer RR 0.99 (CI 0.96–1.03)
no preventive effect on cancer according to type of antioxidant, or
type of cancer
significant increased risk of bladder cancer RR 1.52 (CI 1.06–2.17)
in a subgroup of four trials
Myung et al; Ann Oncol 2010
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67 randomized controlled trials, 232,550 subjects
No effect on primary or secondary prevention of disease,
Vitamin A, selenium and Vitamin E supplements may increase
mortality
Bjelakovic et al: Cochrane Rev 2008
Superfood: a definition
“a food considered
especially nutritious
or otherwise
beneficial to health
and well-being”
OED
THE TIMES: Top 100 foods to boost productivity
Superfoods list, 2007
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almonds
aronia berry
banana
cauliflower
cherry juice
chocolate
fig
guava
kiwi
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mushrooms
oregano
quinoa
rabbit stew
seaweed and
algae shake
tea
tofu (-)
tomato
walnuts
Anti-oxidant potential
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Remove or reduce free
radicals or other reactive
oxygen species (ROS)
that can cause cell
damage
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facilitate anti-oxidant
enzyme reactions
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Moderate the production
of toxic metabolites
Phase I detoxification
Phase I enzymes involved are 'activators'. Common enzyme
group are the CYP groups eg CYP450
They alter the chemical your body needs to remove, by adding
single nitrogen or oxygen molecules. This small change makes it
simpler for Phase II enzymes to effectively remove the substance
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Oxidation
Reduction
Hydrolysis
Hydration
Phase II detoxification
Phase II enzymes called
'excretors' bind to the byproduct
of Phase I enzymes
They conjugate with the altered
chemical such as glutathione.
This makes the substance water
soluble, for easier transport and
elimination
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Sulphation
Glucuronidation
Acetylation
Methylation
Amino acid conjugation
Hussain et al. Nature Reviews Cancer 3, 276 2003
Polyphenols:
Flavonoids
Flavonols: tea, onions
Flavones: parsley, celery
Flavanones: citrus fruits, tomato, mint
Isoflavones: soya, red clover
Anthocyanidins: red wine, black or red fruits
Flavanols: tea, wine, chocolate
Phenolic acids
Hydroxybenzoic acid: tea, blackberries, raspberries
Hydroxycinnamic acids: coffee, blueberries, wheat
Phenolic
alcohols
Tyrosol: extra-virgin olive oil, wine, beer
Stilbenes
Resveratrol: grapes, berries, peanuts
Lignans
Secoisolariciresinol: flaxseed
D’Archivio et al; 2007
Problems with food assays:
unstable phytochemicals
In vitro (‘test-tube’)
degradation over time
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Oxidation of this anti-oxidant forms hydrogen peroxide+ quinones
Shift oxidative damage from lipid peroxidation (cell membranes) to thiol
arylation (less potent damage)
Free radical toxicity is blocked BUT exchanged for a lesser type of toxicity
Disadvantage in test tube monitoring – different in the body
Curcumin
Thangapazham et al; AAPS Journal 2006
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anti-inflammatory,
antioxidant, and
antitumour properties
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The effects of
polyphenols - such as
curcumin - are more
pronounced in vitro, using
high concentrations which
are not physiologically
achievable from food, in
vivo
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A clinical dose of 3.6g
curcumin is sufficient to
achieve in vivo
biochemical influence
Curcumin (diferuloylmethane)
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Turmeric powder contains 3.1%
curcumin by weight, so
‘research-to-recipe’ equivalence
would require consumption of
110g of turmeric powder daily
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‘Curry prevents cancer’ is clearly
an exaggeration of the
knowledge currently available
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poor curcumin bio-availability
can be exploited to afford bowel
prophylaxis for familial
adenomatous polyposis – topical
influence reduces size and
amount of pre-cancerous polyps
forming in the large bowel
Phytochemical bioavailability:
influenced by cooking
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Lycopene bio-availability increased 55%
Increased naringenin
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Increased carotene availability
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Glucosinolates:
z Boiling 30 mins È 70%
z Steaming, microwaving, stir-frying Æ no
change in bioavailability
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Quercetin:
z 75% loss from boiling for 15 minutes
z 65% after microwave cooking
z 30% after frying
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Physiological duration:
pomegranate juice vs tea
Ellagitannins half life of 2-3 hours
Seeram et al; J Nutr 2006
EGCG and other tea catechins half life of 2-4 hours
Yan et al; J Nutr 2004
It’s inevitable that …
“Food, not specific nutrients, is the fundamental unit to
health in human nutrition”
Professor Linda Tapsell
Director of the Smart Foods Centre
University of Woolongong, W Australia
“We are confusing ourselves and the public by talking
so much about nutrients when we should be talking
about foods…”
“consumers get the idea that diet and health can be
understood in terms of specific nutrients”
“It’s not the best approach and may be wrong”
Professor David Jacobs
University of Minnesota
Mediterranean diet:
examples of dietary synergy
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Vitamin D (oily fish) helps absorption of dietary calcium (dairy
foods, green leafy veg)
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Prebiotic fibres in vegetables and grain-based foods provide fuel
source for bowel or probiotic bacteria and increase mineral
bioavailability
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Olive oil aids absorption of phytochemicals (such as lycopene,
lutein) and fat soluble nutrients – vitamins including beta-carotene
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Mono-unsaturated fats reduce inflammation, as do fish oils
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Vitamin C helps to absorb non-meat sources of iron
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citrus flavonoids eg quercetin + Vitamin C work synergistically
FA synthesis
Urea cycle
Summary
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‘Superfood’ is a marketing concept,
exploiting the biological functionality of
food compounds
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Cancer chemoprevention with dietary
phytochemicals continue to be evaluated
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A ‘whole diet’ approach is the optimal
approach to health: a ‘Superdiet’ rather
than ‘Superfood’ approach