Download busting some common dairy myths

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Low-carbohydrate diet wikipedia , lookup

Abdominal obesity wikipedia , lookup

Obesity and the environment wikipedia , lookup

Calcium wikipedia , lookup

Vegetarianism wikipedia , lookup

Human nutrition wikipedia , lookup

Diet-induced obesity model wikipedia , lookup

DASH diet wikipedia , lookup

Saturated fat and cardiovascular disease wikipedia , lookup

Food choice wikipedia , lookup

Nutrition wikipedia , lookup

Dieting wikipedia , lookup

Transcript
dairy
January 2013
nutrition
news
Welcome
Food myths often lead to
unnecessary dietary restrictions,
nutritional deficiencies and ultimately
may have an adverse effect on a
person’s health. Misinformation about
milk and other dairy products has
been circulating for decades, but the
truth is, dairy foods such as milk,
yogurt and cheese are associated
with a reduced risk of many chronic
diseases. In this edition of DNN,
we will separate fact from fiction by
busting some common dairy myths,
drawing on the latest evidence-based
science. Does switching to reducedfat dairy lower your risk of coronary
heart disease (CHD)? Do regular-fat
dairy foods cause weight gain?
Read on to find out!
Best wishes,
The Editor
Glenys Zucco BSc., BA., ND., APD.
Follow me on Twitter
@dairydietitian
T: +61 3 9694 3842
E: [email protected]
Inside
Busting some common Dairy myths
Back page: Recipe
Beetroot Lentil and Feta Salad
hs
od Myt
Dairy Fo
k low
uld drin
milk can
fat milk’
nes’
ney sto
cause kid
nking
ation
TH - ‘Dri
Dairy MY
the form
against
s).
Fo
protect
od yM
ed oxalate
TRUTH
ally help
salts call
that
ma actuyths
de up of
food so
„„Milk
stones (ma
lates in
ucing
rs sho
oxa
y, red
uced fat
‘Toddle
of kidney
binds to
the bod
that red
MYTH .
in milk
orbed by
es advise
rs of age
calcium
Guidelin
er be abs
two yea
„„The
TRUTH
an
no long
an Dietary children below
k fat is
they can
stones.
Australi
years, mil vitamins.
„„The
able for
e’
of kidney
of two
GOOD
Man
not suit
ble
the risk
y favourit
cause acn
the age
milk is
H E A LT
as fat solu
e foods,
ry foods
dren
n below
critint
H & N
as well
ing dai
cism
as.chil
includin
‘Eat
For childre rce of energy
UTRIT
The
orta
g
TH
n acne
informa MY
dairy, attr
ION
less impoutline
foods
nt sou
tion pro
act unw t a link betwee
s er
the trut
importa
becomes
ause oth
porarranted
THvided in not sup
of milk
od becwit
TRU
diet. h behind
s fact she
eati
ir ng
many of doethis
MYTH - the
fat content ncy into childho oils to hthe
dairy foo
et
„„The
the myds
.
gy and ‘Milkacn
„„Science
infa
and Dai
ds.
use
e
cau
tolo
ths
fats
foo
from
the
ma
y
ses
associatof Der
t
ry foo
end incl
mucus’
TRU
tribute
move
y ed
and dair
TH e tha
s stat
recomm ds yea
ude
rs, milk
n that con
Academ
tologist
type,
an
delines at leas
two
ma
,
eric
t
„
Gui
are eate
che
n
skin
ten
„
Der
Num
Am
as
ese
r tha
essent
The and
Dietary
use
ege of
„„
n olde
iald nutrien
ors such erous
yognurtColl
ntalies
„„pro
Australian
k may be
asia
and pro. Other fact
ironmestud
for childre Skim
mu
ts
sho
mil
tral
k
tein
incl
env
cus
w
Aus
„„The
mil
vide
diet
to
udin
;
that milk
production
d fat
g: sed by
diet. „
years old.
exposure
DOES NOT
.
.
„„Som
fiveohy
of reduce
a varied
„
ofcarb
is not cau
ily
nes, and
cause
involvede peopleof fresh
is part of
the age
k ine;fam
s, hormo
mildrat
ly to be ove plen
ty may exp
n from
when it
„of
genetic
„skim
g
n older
erience
more like
for childre
the use vitamin
includinr the moens
a thin, tem
uthure
(A,dre
forschil
utants are
as drink
B12, and
and
prevent
nced diet ofte
cream,
n ds
porary
miswill
riboflav poll
uld not
y foo
taken for throat after drin
lthy bala
and ice„„minerals (cal
in); and
This sho
-fat daircreamy
king milk coating
custard
mu
ng a hea
and low
, phosph „„Eati
potassium ciumose
such as
. This is
it needs.texture. This cus but is sim
orus, ma t, vegetables
meals,
ply milk
andlact
nutrients lasts for
rs.
is not har
zinc).
frui
esting
the
gne
yea
’s
Thre
all
dig
only
sium
nat
s
y
two
mful and
ural
a short
culte serves id milk and
,get
than
„„Too
e diffi
period of
of
the sen
your skin
recomm
much mu
sation
uld avo dairy foods a
who hav
time.
cusds,is from
‘Those
day will
nce) sho ended
as infectio
foo
typ
MYTH provide your diet
intolera serve is equ daily intake
as dairn,y dry air,ner ically caused
of calcium iry
inthe
ts’
(lactose
suchditio
al to one
by things
titio dehydra
Da
group, con
ry producof yogurt
for most
glas
ns.l Prac
diet
such
tion and
s (25
jor food
the
or two from
other dai
a Genera
0ml) of
a ma
nutrient
ple.
certain
g peo
slices (40 g the
ed
MYTH milkudin
medica
e
result in
advice from
Avoidin
, a tub (20
t One
eliminat
g) of che Excl
‘Milk
stin
hou
l
consum
titian can
causes
d to beg or remficu
. Soast
lty dige
0g) tising Die
ese.your diet wit
TRUTH
not nee
TRUTH health at risk
(dif ovin
meanesti
hm
do
g
on
Prac
dair
ue
ds
a’
r
you
y foods
ited
foo
uniq
you
miss out
maldig
„„Dairy
„„Milk to obtain the
or Accred and may put
.
on you k up from you
e lactose ofinma
nyk).vita
r diet cies
dayis rarely foods provide
mil
if you hav e lactose
can drinr recommendeddeficienma
y
y every
son
and
particularlyldigmin
ts dairya trigger for asth
minms
drat
of
dieteary
es of dair „„nutrien
erals
ma calcesti
serv
mon trig
essent
ma.
carbohy
intake essential Com
ium
lactose
t .sympto
es.ial forthre
gers for
with Bef
ten
as house
good hea
ore day withou
meal tim
e oflth,
asthma
people
ovingatdair
packag
dust mit
milk a rem
separate
include
„„Most
ofsee
ed
ally
ses
es
exe
alle
y
k
usu
and poll
fooon
glas
adv sum
rcise.
rgens suc
ds can
from you
to two
ens, vira
y are conice from aldig
h
Gen
l infectio
ma heaesti
eral Prac
nce, if the
„„Foods,
lth tainfess
virtuallyr diet, you sho
lactose
ns and
intolera
titioner s conpro
drinks and
iona
uld
er from
l such
ese
or
t help
food che
Acc a tha
of all peo
who suff
Most che d an
ited Prac as your
bacterired
micals affe
ple with
yogurt.
„„Those
s goo
ticing Die
asthma
ese and
ct less tha
„„The
titian.
.
urt contain
eat che
Nationa
n 2.5%
and yog
with asth l Asthma Council
no lactose ose.
ma sho
reco
lact
st
mm
uld
variety
ends tha
eat a nut
to dige
of foods,
t people
ritious
includin
“Avoid
„„Researc
g milk and diet from a wid
h in
ing or
e
other dair
may actu preschool chil
y produc
dren sug
ally red
ts.
foods fro removing dairy
ges
uce the
risk of bec ts dairy foods
MYTH m your
‘I have
oming asth
diet may
to stop
mean yo
matic.
eating
if I want
u miss
dai
ry
to lose
TRUTH
out on
weight’ foods
recomm
yo
„„A wei
ended
ur
ght loss
dietary
of man
diet sho
help
uld
intake
meet nut
y vitam
rient nee still include dair
foods ava
ins and
y produc
ds. There
ilable, suc
essentia
ts to
are many
mineral
reduced
h
low fat
l for go
fat cheese as skim milk ,
s
dair
low fat
.
od heal
„„Getting
yogurt and y
th.”
eno
is difficult ugh calcium and
if dairy
other ess
foods are
ential nut
„„In add
not incl
rients
ition
uded in
faith.
a low inta research sugges
the diet
in good visit
and
.
ts that if
ke of dair
attention, our resources, 987
e
in a calo
care and
y
227
any of
due you
nor
onma
ds, incl
assistanc
60 105
rie control foo
ABNhav
hed with
lially
udininformation Austra
dge the the
e
further g 3 Dairy
greater
ledrial is publis
cil in
y acknowle
ions. serve
ion. For
All mate eatin
w
1
Dairy Nutrition News January 2013
efull
Coun
nly.
blicat
plicat
BUSTING SOME
COMMON DAIRY MYTHS
MYTH: ‘Cutting back on dairy foods
helps with weight loss’
TRUTH: Including at least 3 daily serves
of dairy foods within an energy-restricted
diet can assist weight and body fat loss,
particularly from the waist, and promote
maintenance of muscle mass.
With 63% of Australian adults currently
overweight or obese,1 many people are
searching for the most effective way to
lose weight. A 2012 meta-analysis and
systematic review of randomised controlled
trials demonstrated that including at least 3
daily serves of dairy foods within an energyrestricted diet can lead to significantly greater
weight and body fat loss, greater gain in
body lean mass and greater reduction in
waist circumference compared with a similar
restriction of energy with a low dairy intake.2
This is the summary result from nine
randomised controlled trials with an energy
restriction of almost 500kcal (2090kJ)/day less
than estimated energy requirement. A total of
430 men and women aged between 18 and
70 years took part in weight loss trials lasting
between 8 and 48 weeks. The mean calcium
in control diets was approximately 500mg/d
(about 1 dairy serve) and the mean calcium
in the intervention diets was approximately
1200mg/d, so the evidence relates to an
extra 2-2.5 serves of dairy products/day,
i.e. in total about 3-3.5 serves.
The greater reduction in waist circumference
and body fat loss seen in the high dairy diets
is particularly important as a build up of
abdominal adipose tissue is considered to be
a key risk factor for chronic diseases related to
the metabolic syndrome. Similarly, maintenance
of muscle mass is important during weight loss
to help prevent weight regain.
Three mechanisms have been demonstrated
to explain the beneficial effects of dairy foods
within weight-loss diets: faecal fat loss, fat
oxidation and appetite control. For faecal fat
loss, a 2009 meta-analysis has shown dietary
calcium decreases blood lipid concentrations
and increases their intestinal excretion. The
effect was greater with dairy foods than with
calcium supplements.3 For fat oxidation, a 2012
meta-analysis indicates a low calcium intake
promotes regulatory changes that can reduce
fat mobilisation and oxidation,4 i.e. people tend
to burn less fat when they have a low calcium
intake. For appetite control, some studies
suggest calcium/dairy foods may help reduce
feelings of hunger and the desire to eat.5
MYTH: ‘Switching from regular-fat to
lower-fat dairy foods will lower risk of CHD’
TRUTH: Research shows swapping
regular-fat milk, yogurt and cheese to
reduced-, low- or no-fat versions will NOT
reduce risk of CHD. Consuming enough
of these dairy products is more important
than focusing on the fat content.
There has been a long held view that encouraging
Australians to consume reduced-fat, low-fat and
no-fat core dairy foods rather than regular-fat
varieties leads to improved health, particularly
cardiovascular health. However, it is important
to consider the entirety of the evidence, not just
one or two individual studies. This is best done
by looking at systematic reviews and metaanalyses.
Dairy Myths Fact Sheet
Do you have clients who unnecessarily cut out dairy? Our Dairy
Myths fact sheet has the facts on common myths such as:
• Milk and mucus
• Milk and asthma
• Dairy foods and weight • Dairy and acne
To order free copies visit www.dairyaustralia.com.au/health
1 ABS 2012 Australian Health Survey: First Results
2 Abargouei AS et al., Int J Obes (2012) published
on line 17 Jan 2012 doi:10.1038/ijo.2011.269
3 Christensen R et al., (2009) Obes Rev 10, 475-86.
4 Gonzalez JT et al., (2012) Obes Rev Jun 19.
5 Tremblay A & Gilbert JA (2011) J Am Coll Nutr 30,
449S-53.
A 2011 systematic review and meta-analysis that considered
all of the published prospective cohort studies reporting the
relationship between consumption of dairy foods and CHD
showed that there was no significant association between
‘high-fat dairy product intake’ and CHD risk (RR: 1.04; 95%
CI 0.89, 1.21) or ‘low-fat dairy product intake’ and CHD risk
(RR 0.93; 95% CI: 0.74, 1.17)6 (see Figures 1 and 2).
Similarly, a 2012 systematic review concluded that the
observational evidence does not support the hypothesis
that dairy fat or high-fat dairy foods contribute to
cardiometabolic risk.7
According to the evidence statements in the Australian
Dietary Guidelines, higher levels of core dairy foods
consumption (regular-fat and reduced-fat) are associated
with reduced risk of heart disease, stroke, hypertension,
colorectal cancer, type 2 diabetes, metabolic syndrome
and improved bone mineral density. Therefore, the
important message is to advise people to consume at least
their minimum recommended intake of core dairy foods
(milk, yogurt, cheese and custard) for their age and gender.
No significant association between total ‘high fat’ dairy
consumption and CHD risk
Figure 1: Forest plot for the relationship between total high-fat
dairy (per 200g/day) and CHD, dose-response meta-analysis
6% Weight
Relative risk
of 4 prospective cohort studies (n=274,680; n cases=3,418).
year
country
(95% CI)
author
(ref) (21) year
Al−Delaimy
2003
country
USA
Relative risk
% Weight
(95%
CI) 1.24)
0.95 (0.73,
33.88
Bostick (9) (21)
Al−Delaimy
1999
2003
USA
USA
1.02 (0.73,
(0.63, 1.24)
1.66)
0.95
10.34
33.88
Engberink
Bostick
(9) (44)
2009
1999
Netherlands
USA
1.08 (0.63,
(0.69, 1.66)
1.69)
1.02
12.26
10.34
Hu (22) (44)
Engberink
1999
2009
USA
Netherlands
1.10 (0.69,
(0.87, 1.69)
1.40)
1.08
43.51
12.26
Overall
Hu
(22)
1999
USA
1.04 (0.87,
(0.89, 1.40)
1.21)
1.10
100.00
43.51
1.04 (0.89, 1.21)
100.00
author (ref)
(I–squared = 0.0%, p = 0.868)
Overall
NOTE: Weights are from random effects analysis
(I–squared = 0.0%, p = 0.868)
NOTE: Weights0.1
are from random effects analysis
0.1
1
2
4
2
4
relative risk
0.5
1
relative risk
No significant association between total ‘low-fat’ dairy
consumption and CHD risk
Figure 2: Forest plot for the relationship between total low-fat
dairy (per 200 g/day) and CHD, dose-response meta-analyses
of 3 prospective cohort studies (n=240,194; n cases=3,018).6
MYTH: ‘Most Australians consume plenty
of dairy foods’
TRUTH: In Australia, six out of ten males and seven
out of ten females (12+ yrs) do NOT meet their
minimum recommended core dairy food intake.
The estimated annual healthcare cost attributable
to low intake of core dairy foods is $2 billion.
0.5
author (ref)
year
country
Relative risk
(95% CI)
Hu (22)(ref)
author
1999
year
USA
country
Relative risk
% Weight
0.70 (0.51,
27.14
(95%
CI) 0.97)
Engberink
(44)
Hu
(22)
2009
1999
Netherlands
USA
1.02 (0.51,
(0.81, 0.97)
1.27)
0.70
37.83
27.14
Al−Delaimy(44)
(21) 2009
2003
Engberink
USA
Netherlands
1.06 (0.81,
(0.83, 1.27)
1.35)
1.02
35.03
37.83
Overall
Al−Delaimy
(21)
USA
0.93 (0.83,
(0.74, 1.35)
1.17)
1.06
100.00
35.03
0.93 (0.74, 1.17)
100.00
2003
(I–squared = 55.7%, p = 0.105)
Much attention is given to Australians’ low consumption
of fruit and vegetables and to their overconsumption of
junk food. However, a new paper in the Australian and
New Zealand Journal of Public Health revealed a high
proportion of adults and children with less than the minimum
recommended core dairy food intake.
Overall
NOTE: Weights are from random effects analysis
% Weight
(I–squared = 55.7%, p = 0.105)
NOTE: Weights0.1
are from random effects analysis
0.5
1
2
4
2
4
relative risk
0.1
0.5
1
relative risk
The researchers from the University of South Australia’s
Health Economics and Social Policy Group then assessed
the scientific literature on the health effects of core dairy
food consumption (both positive and negative) and used
the best available evidence to estimate the direct healthcare
expenditure and burden of disease attributable to low
dairy consumption within Australia. They concluded that if
Australians’ dairy consumption were to be at the minimum
recommended levels, the annual healthcare cost savings
would total $2 billion – an amount comparable to the entire
budget for public health interventions.9
Doidge & Segal (2012) found that 58% of males and
73% of females aged 12+ years consumed less than the
minimum recommended core dairy food intake for their
Males
age as outlined in the 1998 Australian Guide to Healthy
100%
8
Eating (2 daily serves for adults and 3 for teens). The
situation was even worse for adolescents, with 62%
75% of boys
and 83% of girls not meeting their minimum dairy intake
50%
recommendation (Figure 3).
25%
0%
Figure 3: Proportion of Australians meeting the minimum
dairy recommendations (2 serves for adults, 3 for teens).8
Males
100%
75%
75%
50%
50%
25%
25%
25–
29
3545–
55–
39
49
59
Age (years)
65–
69
75–
79
not meeting recommendations
meeting recommendations
0%
12–
15
19
25–
29
3545–
55–
39
49
59
Age (years)
Females
100%
75% Nutrition News January 2013
Dairy
50%
19
Females
100%
0%
2
12–
15
65–
69
75–
79
12–
15
19
25–
29
3545–
55–
39
49
59
Age (years)
65–
69
75–
79
MYTH: ‘People with lactose intolerance should
completely avoid dairy’
TRUTH: People with lactose intolerance can consume
dairy foods by following some simple guidelines.
Needless avoidance of dairy foods can have a
negative impact on a person’s health.
According to a consensus statement issued by the US
National Institutes of Health (NIH), people often mistakenly
ascribe symptoms of a variety of intestinal disorders to
lactose intolerance without undergoing testing.10 As a result,
many individuals who think they are lactose intolerant are
not lactose malabsorbers (i.e. they do not have a deficiency
in their levels of lactase, the enzyme that digests lactose).
The consensus paper concluded in most cases, individuals
with lactose intolerance (the syndrome of diarrhea,
abdominal pain, flatulence and/or bloating after lactose
ingestion) do not need to eliminate dairy foods completely
and suggested they can consume small quantities of milk,
yogurt and hard cheese. It points out that people who have
been diagnosed with lactose malabsorption (usually by a
breath hydrogen test) can ingest 12 grams of lactose (the
equivalent of 1 cup of milk) without symptoms, particularly
if it is ingested with other food.
Many dairy foods do not contain large amounts of lactose
(see Table 1). For example, most cheeses such as
Parmesan, Cheddar and Swiss contain virtually no lactose
and are usually well tolerated. According to the consensus
paper, yogurt is generally much better tolerated than milk
by individuals with lactose malabsorption.
Table 1: Lactose content of Australian dairy foods11
Food
Lactose content (g)
200ml whole milk
12.6
200ml reduced-fat milk
11.2-12.2
200ml skimmed milk
10.0-11.2
200g yogurt
6.0-10.6
40g cheese
0-0.04g
Unfortunately, many individuals with real or perceived
lactose intolerance needlessly avoid dairy foods and ingest
inadequate amounts of calcium, which, according to the
consensus statement, may predispose them to decreased
bone accrual, osteoporosis and other negative health
outcomes.
6 Soedamah-Muthu SS et al (2011) Am J Clin Nutr 93, 158-71.
7 Kratz M, et al (2012) Eur J Nutr DOI 10.1007/s00394-012-0418-1
Published on line 19 July 2012.
8 Doidge JC & Segal L (2012) Austr NZ J Public Health 36: 236-40.
9 Doidge JC et al (2012) J Nutr 142: 1-9 (Published on line 24 July 2012).
10 NIH Consensus and State-of-the-Science Statements 27, 2
http://consensus.nih.gov/2010/lactose.htm
11 NutTab 2010.
12 Abargouei AS et al., Intl J Ob (2012) published on line 17 Jan 2012
doi:10.1038/ijo.2011.269.
13 Louie JCY et al., (2011) Obes Rev 7 e5882-92.
14 Kratz M, et al., (2012) Euro J Nutr DOI 10.1007/s00394-012-0418-1
Published on line 19 July 2012.
15 Fogelholm M et al., (2012) Fd Nutr Res 56: 19103
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3418611/
3
Dairy Nutrition News January 2013
MYTH: ‘Milk, yogurt and cheese (particularly
regular-fat varieties) are fattening’
TRUTH: Research indicates that consumption
of core dairy foods, including regular-fat versions,
is not associated with weight gain or body fat gain.
Despite the acknowledged health benefits of core dairy
foods, there is sometimes a reluctance to recommend an
increase in consumption of dairy foods due to concerns
over their effect on body weight. However, a 2012
systematic review and meta-analysis published in the
International Journal of Obesity has shown this concern is
unwarranted. When adults not on a weight-loss diet were
simply asked to increase their dairy consumption there was
no significant change in their body weight, body fat mass,
waist circumference or lean body mass.12
This result is based on data from five randomised-controlled
trials involving a total of 453 men and women between the
ages of 18 and 85 years. The subjects in the intervention
groups increased their intake of core dairy foods (up to
approximately 3-3.5 serves/day) for 21 to 48 weeks and
those in the control groups maintained their habitual diet
(which included approximately 1 serve/day of core dairy
foods).
As regular-fat dairy foods are higher in kilojoules than their
reduced-fat counterparts, it is often assumed that the fat
content of dairy foods influences their impact on weight gain
and risk of overweight and obesity. However, three recent
systematic reviews have concluded that this is not the case.
A 2011 systematic review by Australian researchers found
low-fat dairy products were not more beneficial for weight
status than regular-fat dairy products and in fact, the reverse
may be true.13 Similarly, a 2012 systematic review concluded
‘The observational evidence does not support the
hypothesis that dairy fat or high-fat dairy foods contribute
to obesity or cardio-metabolic risk, and suggests that
high-fat dairy consumption within typical dietary patterns
is inversely associated with obesity risk’.14 Also, a 2012
systematic review undertaken for the review of the Nordic
Dietary Guidelines concluded there is suggestive evidence
that ‘high-fat dairy products’ have a ‘protective role against
increasing weight.15
In addition to this observational evidence, a randomisedcontrolled trial in Australian children conducted by the
CSIRO found energy intake and adiposity were unchanged
when 76 children changed from regular-fat to reduced-fat
dairy foods for six months.16
MYTH: ‘Osteoporosis is rare in countries such
as China where people have a low dairy intake’
TRUTH: According to the International Osteoporosis
Foundation, vertebral fractures are as common
in Asian populations. Numerous studies have
demonstrated an adequate calcium/dairy food intake
is critical for good bone health in both Asian and
Western populations.
This myth often comes up in discussions about the benefits
of dairy foods for bone health. However, it is important
to appreciate that firstly, osteoporosis is a very significant
health problem in Asian countries with low dairy intakes
and secondly, numerous studies have demonstrated an
adequate calcium/dairy food intake is critical for good bone
health in both Asian and Western populations.
A landmark 2009 report by the International Osteoporosis
Foundation (IOF)17 highlighted that 50% of all osteoporotic
hip fractures will occur in Asia by the year 2050 and that
osteoporosis is greatly under diagnosed and undertreated
in Asia. According to the report, vertebral fractures are as
common in Asian populations as in Caucasian populations.
In addition, there has been a 2- to 3-fold increase in the
incidence of hip fracture in most Asian countries during the
past 30 years.
Randomised controlled trials have shown increased milk
intake improves total body bone mineral content18 and total
hip bone mineral content19 in Chinese children and helps
to reduce bone mineral density loss in post-menopausal
Chinese women.20 Average dietary calcium intake for the
adult Asian population is approximately 450mg/day and the
IOF recommends the very low calcium intake is addressed
through nutritional guidelines and information campaigns
in an effort to raise calcium intake among all age groups,
especially the young.
MYTH: ‘Dairy is a trigger for asthma’
TRUTH: Dairy foods are not a common trigger
for asthmatic symptoms.
A 2012 review has summarised the available evidence
examining the link between milk consumption and
asthma. It concluded ‘current evidence does not directly
link milk consumption and asthma’.21 This is consistent
with the conclusion of a 2005 review that concluded
‘recommendations to abstain from dairy products due
to the belief that they induce symptoms of asthma are
not supported by the body of research evidence on the
relationship between dairy consumption and occurrence
of asthma’.22 Despite this lack of evidence, a recent survey
found 54% of Australian general practitioners reported that
their patients eliminated or restricted their intake of dairy
foods due to asthma.23
Both reviews highlight the potential dietary imbalances that
can occur if dairy foods are needlessly eliminated from the
diet. It is thought the belief that milk exacerbates asthma
goes back to the 12th century and was strengthened by its
inclusion in Dr Spock’s Baby and Child Care book, (one of
the bestselling books of its type worldwide over the past
half century).
Known triggers of asthmatic symptoms include allergens
such as house dust mites, pollens, mould spores, animal
fur, tobacco smoke, viral infections and weather changes.
Exercise may also trigger asthma, but appropriate
medication and warm-up exercises can usually control this.
Food is not a common trigger for asthma apart from those
with food allergies or chemical intolerances. The National
Asthma Council recommends people with asthma should
eat a nutritious diet from a wide variety of foods, including
milk and other dairy products.
16 Hendrie GA & Golley RK (2011) Am J Clin Nutr 93, 1117-27.
17 Mithal, A et al. (2009) International Osteoporosis Foundation, Switzerland
18 Du X et al., (2002) Brit J Nutr 92, 159-68.
19 Lau EMC et al., (2004) Osteoporos Int 15, 654-8.
20 Lau EMC et al., (2001) J Bone Miner Res 16, 1704-9.
21 Thiara, G & Goldman, RD. (2012) Can Fam Phys 58; 165-166.
22 Wuthrich B et al., (2005) J Am Coll Nutr 24, 547S-555S.
23 Dairy Australia, GP survey 2011.
4
Dairy Nutrition News January 2013
MYTH: ‘All food sources of calcium are
equally beneficial’
TRUTH: When assessing dietary sources of
calcium, it is important to consider both the calcium
bioavailability and the calcium content per serve.
The 2003 Dietary Guidelines for Australians24 recognise that
few foods provide as much absorbable calcium per serve
as dairy food. Although dairy ‘alternatives’ are often fortified
with calcium, some studies suggest the bioavailability
of the added calcium is not equivalent to the calcium
naturally present in milk. For example, Heaney reported
that, compared with milk, 25% less calcium was absorbed
from a soy drink fortified with tri-calcium phosphate to the
equivalent level found in milk.25 Lower calcium bioavailability
with tri-calcium phosphate was also reported by Zhao et
al., but a calcium carbonate fortified soy drink had a similar
calcium bioavailability to milk.26
Although calcium is naturally present in foods such as
green leafy vegetables and legumes, the amount of calcium
present in one serve is lower than that in dairy foods. The
bioavailability of calcium in these foods can also be affected
by other nutrients that inhibit calcium absorption including
phosphates, phytic acid from the husks of cereals and
oxalic acid.27
Recent dietary modelling utilising the NHANES 2003-2006
database examined the impact of substituting dairy foods with
alternative calcium sources.28 Based on the US MyPyramid
food pattern, the modelling showed the replacement of a
serve of dairy foods required 1.1 serves of fortified a soy
drink, or 1.2 serves (204 g) of bony fish (e.g. canned sardines
or pink salmon with bones), or 2.2 serves (1.1 cups) of leafy
greens (including kale, spinach, collards, and turnip greens)
to meet equivalent calcium intakes.
MYTH: ‘Dairy protein leaches calcium from the bones’
TRUTH: A high protein diet is not detrimental to
bone health. If anything, a higher protein diet may be
slightly beneficial, particularly if baseline protein is
low. Dairy foods play an important role in bone health.
This myth seems to have arisen because increased protein
intake can lead to increased calcium loss in the urine. A
comprehensive 2012 review concluded that although high
protein diets induce an increase in urinary calcium excretion,
they do not seem to be linked to impaired calcium balance.29
The authors pointed out that no clinical data support the
hypothesis of a detrimental effect of a high protein diet on
bone health, except when there is an inadequate calcium
supply (obviously, this is never the case with dairy foods).
They suggest increased absorption of calcium from the
intestine explains why urinary calcium tends to increase
on a high protein diet.
In 2011, Kerstetter and colleagues reviewed the evidence
supporting the hypothesis that high dietary protein may
support calcium metabolism and bone health.30 They
concluded ‘recent epidemiological, isotopic and metaanalysis studies suggest that dietary protein works
5
Dairy Nutrition News January 2013
synergistically with calcium to improve calcium retention and
bone metabolism.’ They warned ‘the recommendation to
intentionally restrict dietary protein to improve bone health
is unwarranted, and potentially even dangerous to those
individuals who consume inadequate protein.’
MYTH: ‘Cheese is acid-producing and therefore
detrimental for bone health’
TRUTH: This hypothesis is not evidence-based. The
body is able to buffer acid produced from foods such
as cheese. The nutrients in cheese make it beneficial
for bone health.
The ‘Acid-ash’ hypothesis states that ‘acid’ from modern
diets causes osteoporosis and that an alkaline diet or
‘alkaline’ supplements or salts prevent osteoporosis.
According to the hypothesis, food such as hard cheese and
meat are very acidic, bread and milk are slightly acidic, and
vegetables and fruit are alkaline.31 The idea is that structural
bone mineral is dissolved to release bicarbonate so that
acids can be neutralised and systematic acidosis is avoided.
In 2011, a group of researchers from the University of
Calgary in Canada published a systematic review of
the evidence for the acid-ash hypothesis.32 The authors
identified 55 studies that met their inclusion criteria,
including 22 randomised interventions. They noted that
none of the intervention studies provided direct evidence of
osteoporosis progression and the 11 supporting prospective
cohort studies were not controlled regarding important
osteoporosis risk factors.
After examining the available evidence the authors did not
find any studies that revealed a biological mechanism that
functioned at physiological pH levels. They also noted that
the randomised studies did not provide evidence for an
adverse role of phosphate, milk foods and grain foods and
osteoporosis. The systematic review concluded ‘a causal
association between dietary acid load and osteoporotic
bone disease is not supported by evidence and there is no
evidence that an alkaline diet is protective of bone health.’
24 National Health and Medical Research Council, Food for Health. Dietary Guidelines for
Australians: A Guide to Healthy Eating. 2003, Department of Health and Aging, Australian
Government: Canberra: Australia.
25 Heaney, RP (2000) J Nutr 131(4 Suppl):1344S-8S.
26 Zhao, Y et al. (2005) J Nutr 135:2379-82.
27 Wahlqvist M ed (1997) Food and Nutrition: Australasia, Asia and the Pacific.
28 Fulgoni, VL et al. (2011) Nutr Res 31, 759-765.
29 Calvez J et al., (2012) Eur J Clin Nutr 66, 281-95.
30 Kerstetter JE et al., (2011) Curr Opin Lipidol 22, 16-20.
31 Wynn E et al., (2010) Proc Nut Soc 69, 166-73.
32 Fenton TR et al., (2011) Nutr J 10:41.
Serves 4
Ingredients
450g can whole baby beetroot, drained
400g can lentils, drained and rinsed
2 spring onions, finely sliced
50g wild rocket leaves
2 teaspoons extra virgin olive oil
1 teaspoon red wine vinegar
¼ cup crumbled feta cheese
freshly ground black pepper, to taste
Beetroot Lentil and
Feta Salad
Method
Nutrition information
1.Cut any larger beetroot in half and
combine with lentils and spring onions
in a bowl. Add the rocket and drizzle
with combined oil and vinegar.
Gently toss to coat.
NutrientPer
Tips/Handy Hints
Serve
To boost protein in this salad, add some grilled
Energy (kJ)
622
chicken or lamb.
Protein (g)
7.5
2.Transfer salad to a serving platter,
scatter with feta and a grinding of
pepper.
Saturated Fat (g)
2.9
Carbohydrate (g)
12.5
Sugars (g)
5.8
Total Fat (g)
Dietary fibre (g)
2.2
Sodium (mg)
407
Calcium (mg)
74
Iron (mg)
0.3
Published by Dairy Australia.
The information in this document is to be used as nutrition education information only.
All material is published with due care and attention, and in good faith but no responsibility
can be accepted for omissions, typographical or printing errors, or situation changes that
have taken place after publication.
© Dairy Australia 2013. All rights reserved. AB/NE/2013/12,000
6
Dairy Nutrition News January 2013
6.5
Dairy Australia Limited
ABN 60 105 227 987
Level 5, IBM Centre
60 City Road
Southbank Victoria 3006 Australia
T: +61 3 9694 3842
F: + 61 3 9694 3888
E: [email protected]
www.dairyaustralia.com.au/health