Reprinted
from ABC website where it is was published on 25.7.18
Its common wisdom that
a healthy diet is key to having a healthy heart, but exactly what that diet
looks like still has some people scratching their heads.
A research paper out on Tuesday aims to answer
the common nutrition questions people ask their heart health specialists.
The Journal of the American College of Cardiology study
aims to act as a guide for cardiologists who, despite having patients look to
them as a source of information on heart-healthy diets, don't get a lot of
nutrition training in their formal studies, according to lead author Andrew
Freeman.
"The vast majority of cardiologists, and
actually lots of medical doctors surprisingly, have very little practical,
day-to-day nutrition knowledge," Dr Freeman said.
Cardiovascular health benefits of controversial
foods.
(Journal of the American College of Cardiology:
Andrew Freeman)
The authors looked at previous studies to see
where the balance of evidence fell on specific foods like dairy, energy drinks
and fermented foods, and nutrients such as omega-3 and vitamin B12.
The bottom line, according to Dr Freeman, was
that whole, plant-based foods where nutrients are delivered in their natural
form seem to be healthiest.
"A
heart-healthy diet and, I would argue, a healthy diet overall really, is a
predominantly plant-based, whole food, minimally-processed, no added salt, no
added sugar type of a diet. And everything else is sort of the details,"
he said.
"For instance, people are very wary about if
there's sugar or carbs in fruits and vegetables and those really don't seem to
be harmful. Whereas if we extract those and have that added sugar, those do
seem to be harmful.
"Same thing when we pull out caffeine to
make energy drinks, versus caffeine that's naturally occurring in coffee and
tea — one's harmful and one's not so harmful."
So what's the verdict on the heart-healthy
credentials of each of the products the authors investigated? Let's take a
look.
Dairy:
Dairy products are a good source of vitamins,
minerals and protein — but they also can contain high levels of saturated fat
and salt, which can contribute to heart disease risk.
"It was very widely split on whether [dairy
carries] harm or benefit. It's very confusing and confounding," Dr Freeman
said.
"But all the authors agree that dairy
appears to be the number one source of saturated fat and salt in the American
diet."
Achieving a healthy intake of dairy is possible
if you make good choices within the Australian dietary guidelines of two and a
half serves a day, according to advanced accredited practicing dietician
Melanie McGrice.
"It depends on the type of dairy products
you're talking about," she said.
"If you're talking about full cream milk
versus low fat milk you're talking about a 1 per cent difference in fat …
whereas if you're talking about the difference between, say, milk and cream,
then you're talking about a 50 per cent fat difference.
"As long as people stick to lower-fat types
of dairy product like milk, yoghurt and even cheese, then they're going to be
fairly safe in terms of cardiovascular disease."
Added sugars:
Links between added sugars and increased risk of
cardiovascular disease started to surface in the 1950s, and the weight of
evidence has built steadily since, the authors wrote.
Studies they looked at showed added sugars,
especially the fructose portion of table sugar or syrups used in food
manufacture, contributed to fatty deposits in arteries, even if the person
consuming the sugar wasn't gaining weight.
But, as Dr Freeman said, naturally occurring
sugars in whole foods like fruit and vegetables don't seem to have the same
detrimental effects.
Legumes:
Lentils, chickpeas, soybeans and their ilk have a
range of heart-healthy benefits, the study found, including a reduced risk of
death from all causes, reduced risk of coronary heart disease, and better blood
glucose control. For this reason, the authors issued an enthusiastic
endorsement of legumes.
But Dr Freeman admitted getting people excited
about brewing up a batch of lentils was harder than selling a new breakthrough
drug or procedure.
"Which is sexier? The latest statins or
percutaneous and minimally invasive valves, or peas and carrots? There's not a
lot of money in peas and carrots and, if given an option, there are lots of
people who would rather take a pill or have a procedure than to change
something drastic in their lifestyle," he said.
"But I would tell you if you go to certain
parts of the world where diets are predominantly legumes, you know, beans,
rice, vegetables, heart disease is extremely low."
Tea, coffee:
Added sugar and fat notwithstanding, both coffee
and tea are linked to cardiovascular health, the study found.
Coffee sometimes gets a bad rap for increasing
blood pressure, but the authors noted this wasn't a problem in people who drank
it regularly. In fact, it contains antioxidants that are linked to good health,
and habitual coffee drinking is associated with a lower risk of death from
cardiovascular disease.
Similarly, both black and green tea have a high
antioxidant content and have been shown to benefit cardiovascular health.
But if you think getting caffeine in any form is
going to help your heart, think again.
"Coffee and tea seem to be somewhat
healthful, whereas the energy drinks, which have extracted the caffeine out of
the plant and created a synthetic cocktail, seem to be somewhat harmful,"
Dr Freeman said.
Energy drinks were linked to cardiovascular
issues, including arrhythmia, elevated blood pressure, seizures and even death.
While the previous studies the authors looked at
weren't of the highest quality, they warned people to avoid energy drinks just
in case.
Alcohol:
Anyone with even a casual interest in health news
would be familiar with the seemingly contradictory advice around alcohol
consumption. The problem is it's a complex issue with so many variables, as the
authors of this review noted.
Low to moderate alcohol consumption is associated
with a reduced risk of cardiovascular disease, and wines specifically contain
compounds that have been shown under certain conditions to have beneficial
effects.
But don't start drinking if you're currently a
teetotaler just to get a health benefit, the authors cautioned, because
drinking carries risks too.
"There is also some risk of falls, certain
cancers, and liver disease," they wrote.
"As such, it is not recommended that
individuals initiate alcohol consumption for [cardiovascular] benefit, and for
those already drinking, consumption should be limited to recommended amounts, preferably
consumed with meals."
Fermented foods:
In terms of food fads of the moment, fermentation
would have to be among some of the most popular. But do fermented foods help
your heart?
The evidence isn't strong enough to routinely
recommend them, the authors said, but some studies suggest benefits for risk
factors for cardiovascular disease such as high blood pressure and cholesterol.
Ms McGrice suspected the recent surge in
popularity of fermented foods meant the research simply hadn't caught up yet.
And while there may not be clear evidence linking
fermented foods and heart health, there was evidence for other health benefits.
"It's gut health. What we're seeing now is
with benefits in our gut microbiome that that's having an influence on
inflammation all around the body," Ms McGrice said.
"There's certainly a link between fermented
foods and improving the gut microbiome. What we're finding is that improvement
in the gut microbiome has far-ranging benefits, but its really hard to isolate
exactly what those are.
"And there may be benefits for
cardiovascular disease, but they haven't been detailed yet."
Omega-3s and vitamin B12:
Fish is a good source of omega -3 fatty acids,
but not the only source.
Alongside food groups, the study also looked at
omega-3s and vitamin B12, which have both been shown to have heart health
benefits. What was the best way to get these nutrients, the authors wondered?
For omega-3s, which can be found in both fish and
plants, the evidence was unclear.
"It appears omega-3s are essential to the diet;
the question is … which is a better source?" Dr Freeman said.
"And the jury's still out on that but when
you look at fish, even in the best places, they seem to be contaminated more
and more."
The authors concluded either source was probably
beneficial, especially if it came from a whole food rather than a supplement.
As for B12, the authors recommended supplementing
for people who were deficient in the vitamin. But they said there wasn't much
evidence to support using supplements as a preventative measure for
cardiovascular disease.
"When you look
all the data in sum, a particularly plant-based diet with minimal processing is
really where the health is," Dr Freeman said.
"And it's probably not how most people want
to eat all their meals, but it's actually very doable and very tasty.
"It's just a matter of having the
clinicians, the doctors, and their associated professionals understanding how
to get patients motivated to do this sort of thing."
