Donald D. Hensrud, MD, M.S., M.P.H., discussion on how dairy products may raise bone density, the slight benefit on fracture risk and a few studies around the benefits of dairy relation to CV risk factors.nLearning Objectives: Review the evidence for dairy procudts in bone health and other health outcomes; Describe plant sources of calcium
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Family Medicine & Primary Care Specialty
Internal Medicine Specialty
Public Health Specialty
Nutrition - Dietetics - Wellness Subspecialty
Mayo Clinic
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Past Notes
We'll comment on the monkey
study of caloric restriction.
I remember hearing somebody that
was there in Wisconsin and I
remember hearing one of the
investigators speak on that study
some time ago and they said
the monkeys that
primates are under caloric
restriction were not happy campers.
When the trainer came to feed them,
they'd lash out at the trainer and
everything. So they may have lived
longer, but they didn't live
happier, apparently.
No disclosure, so it's
always interesting about diet and
nutrition that we have certain
beliefs but foods and food groups,
so we're going to take a look at
sometimes we look at the evidence,
such as with breakfast that Dr.
Thompson mentioned the other day.
We're going to take a look at the
evidence on dairy
and review the
bone health and for all the other
health outcomes. So everybody knows
there are different types of dairy
products. There's whole fat, low fat
fermented products such as cheese
with the lactose is fermented.
And then there's fermented products
that may contain probiotics such as
yogurt or Keefer, and they may have
different effects.
Dairy contributes about 10 percent
of the calories to the typical U.S.
diet. Almost half comes from milk,
almost half from cheese and a small
amount from yogurt and other
sources.
And consumption has decreased over
time since 1970,
mainly in milking.
Cream cheese is increased a little
bit and butter is small and stable.
If we look at and and bone
health theory, is it maximizing
bone density early in life may
decrease fracture risk later in
life.
If you look at the evidence, there
is some evidence.
In children, dairy products improve
bone mineral content by a small
amount over a year.
But mainly when the daily baseline
calcium intake was lower.
This has been shown in both
Chinese girls and in
Caucasian girls.
In adults, dairy products
increased bone mineral
density by, again, a small
amount over a couple of years.
With regard to bone mineral density,
dairy products don't appear to be
better than calcium supplements.
Now there's other data that
supplements may cause some
adverse effects.
In the U.K., there's some data on
coronary artery disease and, of
course, renal stones.
But in terms of bone bone health,
it doesn't appear to be much
difference.
What about fracture risk?
There's one study some time
ago, and then based
on data from the Nurses Health Study
and the health professionals follow
up study where
they didn't find an association
between milk consumption during
teenage years and subsequent risk of
hip fracture as an adult.
But the issue here is, can we
accurately recall our
milk consumption as a teenager
many years later?
Among adults, there was a meta
analysis and didn't show much of a
relationship in women
between male consumption
and risk of hip fracture.
Three studies in men showed the
trend toward decreased risk.
But it wasn't statistically
significant.
Other data other than this meta
analysis, there's been some studies
that have suggested that some
milk is associated with a reduced
fracture risk.
But overall, the data on bone
density and fracture risk,
if real, it's probably relatively
small.
And people have looked at
vegetarians and vegans.
And again, the data are difficult
to pin down.
There are potentially lower intakes
of certain nutrients and vegetarians
and particularly vegans.
There may be other
nutrients that are in higher intake.
However, beneficial effects from
potassium, vitamin C, magnesium,
etc.
studies have shown and again, there
isn't a lot of really solid data.
But there may be slightly born,
slightly lower bone density,
predominantly in vegans,
not necessarily in veg.
Vegetarians overall and fracture
risk again appears to be just
slightly higher and begins.
But these data I get are not
tremendously solid.
Deviate a little bit from dairy just
to talk about calcium.
You can see the RDA for
men and women in the United States,
over age 50 women are
recommended to get twelve hundred
milligrams a day of calcium
in older age 70.
Men and women.
Twelve hundred a day.
And if you look around the world,
it's a lot different.
In the U.K., their recommendation
is 700 milligrams of calcium.
And the World Health Organization
recommends more than 500
in countries with a high incidence
of osteoporotic fractures.
So a lot less than the United
States.
The mean intake in the United
States.
This is between the 25th and seventy
fifth percentile, so
the middle half of people
are getting between six and nine
thousand for women.
Eight hundred and thirteen hundred
for men.
But there's as you can see, there's
a wide variability in calcium
intake.
These are just some of the things.
300 milligrams of calcium, just
to keep them number in mind
is in eight ounces of milk, six
ounces of yogurt or one and a half
ounces of cheese.
And also get that in salmon and
cereal, although the amount varies.
For people who don't consume
milk, either by choice or because
of lactose intolerant, there are
plant sources of calcium.
So all of these are one hundred and
fifty milligrams
of calcium.
Two tablespoons Volman Butter,
tahini,
nuts or tofu.
Half cup of fortified
milk, etc..
As you go on down here, even oranges
and in dried figs have some calcium.
So let's switch gears, that's
bone health and just to kind of
summarize, there is does
appear the relationship between bone
marrow density and fracture risk and
dairy intake, but it probably isn't
that strong is what people
think.
Calcium is a critical nutrient,
although the amount that we need is
a little bit controversial around
controversy around that, depending
on what part of the world you're in.
And vitamin D, we haven't talked
about that, but that's probably a
more critical nutrient than in
calcium regarding bone health.
So a question for you.
Dairy products appear to decrease
the risk of which of the following
conditions.
And yeah, so we'll use Dr. Kadesh,
his method for all of the above is
there. Go ahead and take it.
And this is one of the things that I
was a little surprised when I
started looking into the literature.
This is a fairly
recent review.
You can see here they looked at
all kinds of different studies.
Large number of events
related to total dairy consumption,
cardiovascular disease incidence,
coronary heart disease incidence,
stroke, type two diabetes,
hypertension and metabolic syndrome.
There was a beneficial effect
of total dairy consumption
on stroke.
Hypertension, Type two diabetes,
borderline significance
and metabolic syndrome.
So overall,
dairy consumption does seem to have
a beneficial effect on
cardiovascular risk factors.
If you look at individual
dairy products, it's it's it's
interesting, again, they looked at
large number of studies.
Coronary heart disease incidence
appears to be beneficially affected
by cheese.
That was surprising to me.
Milk has a beneficial effect
on hypertension and stroke.
And yogurt beneficial effect
on type two diabetes and you can
say, well, what's going on here?
Nobody really knows what the diff.
Why the difference among the
different dairy products?
The hypothesis that is
the food matrix
of all the nutrients in each
of these products may differ
slightly.
And that might be why the
effect is different.
But it is interesting,
I think, in looking at this.
There was a meta analysis
of five randomized controlled trials
comparing hard cheese with butter
and serum lipids, the
polyunsaturated to saturated
fatty acid ratio was similar
in these trials and
compared with butter cheese reduced
LDL by six point eight percent
and HDL by three point four percent.
But compared with tofu or fat
modified cheese, cheese increased
LDL is expected.
So there's something, again, maybe
with the food matrix separate
from the individual fatty acids
where cheese is more beneficial
than butter.
This is also interesting if you look
at the difference between
full fat and low fat dairy
products, there isn't a clear
difference in many of these C.V
health outcomes that you saw.
And of course, we've been telling
people eat low fat dairy products
for quite some time.
But again, if you look at the data,
both are either neutral or
beneficial, as we saw previously.
There is a recent article in JAMA
that looked at this and a couple of
prominent nutritional
epidemiologists must firing
from Tufts.
And Frank, you from Harvard weighed
in on this, and
that's fine, said I'm not sure that
there's a lot of data
to support either full
fat or low fat dairy products.
He wouldn't recommend necessarily
recommend low fat, overfull fat, but
either one doesn't seem to be as
benefit her.
He wasn't sure that dairy was
necessary despite the data you saw
earlier.
But we do know
from years of research
that there's other data
that suggest that saturated fat will
increase serum cholesterol.
The Keyes equation, etc.
So
there may be some benefit in
decreasing saturated
fat fat by consuming low fat dairy.
But again, the data that
we have don't clearly state this.
There was a recent study published
in Lancet that was a worldwide
study looking at
dairy products that was assessed
by a food frequency questionnaire
and a number of different countries,
very large study.
And more than two servings a day of
dairy was associate with lower total
mortality, cardiovascular mortality,
major cardiovascular disease and
stroke.
And once again, a whole fad appeared
to be as beneficial as low fat dairy
products.
There's a lot of controversy about
this study
in general with population studies.
You have to look at measurement
errors, but
there is a low baseline intake in
some of the country's higher
socioeconomic status was associate
with greater dairy intake.
Some of the countries didn't even
consume a lot of dairy.
And then how the dairy products are
consumed in
France. People made cheese alone.
And in the United States, we usually
combine it with other foods.
And again, populations may react
differently to very Tu's and there's
always unrecognized confounding, so
you have to take these these data
with, I think with a little grain of
salt, but nonetheless did show a
beneficial effect.
Question which the following cancers
has been associated most strongly
with dairy products.
OK.
Let's take a look at this correct
answer, actually, is, B, prostate
cancer.
Some of the background in this
growth hormone is fed to cows to
increase milk production.
This increases IGF one in milk
and we consume the milk.
It mildly increases serum IGF
one in humans.
It's mainly found in milk processing
of other milk to other dairy
products decreases.
IGF one and IGF
one stimulates growth
and differentiates and
differentiation in cells and
inhibits cellular apoptosis.
And so several studies have shown
a correlation between elevated serum
concentrations of IGF one and
increased prevalence of breast,
prostate and colorectal cancer.
Or if you if you look a little bit
deeper, the evidence.
Recent review said the evidence is
not consistent
and suggested that dairy
products at a slight protective
effect. Interestingly enough, in
this review.
While the data are sparse, cultured
milk, yogurt and low fat dairy
products seem to provide the most
benefit.
And this review did note a small
increased risk of prostate cancer
from dairy products.
There is another independent meta
analysis on prostate cancer.
And you can see here it wasn't a
huge risk, but
it was statistically significant
for different dairy products,
increasing the risk of prostate
cancer.
And again, there's some controversy
here.
Non-dairy calcium or supplemental
calcium intakes were not.
So she would total prostate
cancer risk, although supplemental
calcium was associated with
increased risk of fatal prostate
cancer. So how do you
reconcile these data?
It's not entirely clear.
In any case, it may be
an increased risk, but the effect of
that risk is pretty small.
Look at derian body weight
in population studies, dairy intake
increases body weight.
And randomised controlled trials.
Dairy increases body weight when
energy is not restricted.
However, in randomized controlled
trials,
dairy decreases body weight.
Body fat and weight circumference
when accompanied by energy
restriction.
Now, if anybody's heard of A2 milk
here, how many people raise your
hands?
This few people.
So this is interesting.
In milk proteins,
there's 20 percent whey protein, 80
percent casein, 30
percent of this casein is beta
casein. And there are two types.
A one beta casein is found in milk
from cows of northern European
origin. A two is found
in milk from southern France,
Channel Islands and Africa.
And supposedly 5000 years
ago, there was a single mutation
in a two beta casein that caused
a one beta casein
to form.
Regular milk contains both of these,
while A2 milk contains
only this A2 beta casein,
which is more primitive,
I guess, form a beta casing.
If you look further,
VCM seven is an opioid
peptide released during the
digestion of a one beta
casein.
And a few studies have suggested
that this compound may be
linked to Type one diabetes and
possibly heart disease.
But the data are not consistent
and controversial.
There is some evidence, a little bit
more evidence that A1 data Kaseem
is associated with more
gastrointestinal symptoms
than a two beta casein.
So not all dairy intolerance
may be due to lactose and they've
done a few studies looking at this
and people who drank the A2
milk seem to do a little bit with
regarding Jeyes
symptoms.
This is available in New Zealand,
Australia, UK, China and
the US. And it's being
marketed fairly,
especially in Australia, I believe.
So if you see that that's the
rationale might be beneficial
for symptoms, but probably not
with other conditions.
So in conclusion, dairy products
may raise bone density slightly,
particularly in those with a low
calcium intake, have
a slight benefit on fracture risk.
Cohort studies suggest they are
either neutral or favorable with
regard to CV risk factors
and disease.
And there seems to be a pretty
similar benefit on health outcomes
from whole fat or low fat dairy
products for some outcomes,
although other data suggests that
less saturated fat is beneficial.
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