In this portion, we're going to look at the effect of Dietary Fiber and how it
pertains to heart disease risk. Dietary fiber is the plant matter that is
indigestible in human body. And we classify fibers as being either
soluble or insoluble. While there's definitely benefits to both
soluble and insoluble fiber, if you had to choose one over the other, it would be
soluble fiber that's most associated with reduced heart disease risk.
Viscous soluble fibers modestly help to lower LDL cholesterol levels, so that's
the mechanism by which they're related to heart disease risk.
Soluble fibers occur in conjunction with diets that are low in saturated fat and
trans fat and cholesterol. So you already know about the benefits of
cutting out or cutting down on those components of your diet.
Here's something that you can add more to your diet.
Soluble fiber dissolves in water, it forms a gel like substance.
Well, many grains, and whole grains, do contain, both soluble and insoluble
fiber. Oats have the highest proportion of
soluble fiber of any grain. Other good sources of soluble fiber
include foods like oatmeal, oat bran, beans, peas, rice bran, barley, citrus
fruits, strawberries, and apple pulp. Sometimes, people ask you know, should I
eat more soluble or more insoluble fiber, and to be honest most people for that
they are just splitting hairs. You should focus on eating more foods
that contain naturally occurring sources of fiber and you will naturally be
getting both more soluble and more insoluble fiber but for the sake of heart
disease we are going to focus today on soluble fiber.
How does soluble fiber impact your heart health? Soluble fiber helps to improve
hyperlipidemia through the combined effects of the following 3 things.
Soluble fiber helps to delay gastric emptying.
When you eat a food containing soluble fiber, it takes your body a longer time
to digest that food than it would if it didn't have the soluble fiber in it.
It helps to increase the excretion of bile acids.
And to reduce, the hepatic synthesis of cholesterol, which I'll explain in a
moment. Let's look at the gastric emptying
component. Soluble fiber works, to help reduce heart
disease, by the mechanism, of reducing gastric emptying, in the following way.
Soluble fibers take longer to digest. And this plays a role on satiety and
weight control. We know that if you feel full, well, we,
we surmise that if you feel full, you're going to eat less.
If you eat less, you're going to weigh less.
If you have a healthy weight, you're going to be at lower risk for heart
disease. There's also the potential that the
gastric emptying component may have a beneficial effect on insulin sensitivity.
And insulin sensitivity is linked to heart disease risk.
The second mechanism by which soluble fiber works is to increase the excretion
of bile acids. Soluble fiber binds with bile acids in
your small intestine, and helps remove it from the body.
This reduces the rate of bile acid recycling.
The loss of bile acids in your stool stimulates your liver to increase its
uptake from the circulation and to replenish your supply.
The result is that your serum total and LDL cholesterol levels drop down.
But, it's important to note that your HDL and triglyceride levels are generally
unaffected. The third potential mechanism by which
soluble fiber helps to impact heart health is by decreasing your liver's
synthesis of cholesterol. Some soluble fibers belong to a class of
compounds called oligosaccharides. These oligosaccharides are fermented in
the lower portion of your gut into short chained fatty acids, and.
Acids. These short chained fatty acids enter
your circulatory system. And maybe inhibit, or basically tell your
liver to make less cholesterol. So perhaps you've heard that cholesterol
comes both internally and externally. It can come from the foods, if you eat
animal foods in your diet. But your body can also make it.
and perhaps, the more planned foods, with soluble fiber that you make,actually in
turn is helping to reduce the amount of cholesterol that your liver is making
inside of you.Insoluble fibers, to some degree do play a role on heart help as
well.They promote motility in your gut and increase your stool bulk.They also,
They're also linked to lower rates of cardiovascular disease.
All be it, less so then soluble fiber. They help promote satiety which is linked
to a healthy weight. They may help lower your blood pressure
or your risk of blood clots and they may help lower inflammation as well.
So, all of those things do positively impact your heart health.
What's the bottom line here? You should work on eating more sources of fiber from
things like fruits, vegetables, whole grains, and legumes, and not really worry
exactly about how much soluble or insoluble fiber you're getting.
A lot of foods, for example an apple, or a half a cup of dried oatmeal, has f
grams of fiber. Two of those are soluble And two are
insoluble. You get the heart healthy benefits from
the combination of the soluble, you get a little bit more of the gut health
benefits from the insoluble. At the end of the day, both of those are
good things. So the recommendation is to increase the
amount of fiber that you get from foods. Note that these proposed mechanisms have
not been proven from supplemental sources of fiber.
So you can't eat a crappy diet and then turn around and eat a lot of soluble and
insoluble fiber supplements, and think that you're going to get the same
benefits. You have to focus on the foods.
In the United States, the Food and Drug Administration has approved the following
health claim. Now, at first glance, it looks like a
mouthful, and it is, but we're going to break it down piece by piece.
The approved health claim says, that diets that are low in saturated fat and
cholesterol and rich in fruits, vegetables, and grain products that
contain some types of fiber, and in-particular soluble fiber may reduce
the risk of heart disease, a disease that is associated with many factors, okay so
there's not just one thing you can pick out of your diet and say that is going
to. Heart disease in me.
But the important components here are reducing your saturated fat, increasing
your soluble fiber. And keeping in mind that diet is really
just one component of heart disease. You gotta cut back or cut out the
smoking, you need to exercise more. there are some other lifestyle.
Components in there. But when you're looking at diet, go down
on your fat. Go up on your fiber.
What sort of foods have fiber in them? Fruits, vegetables, whole grains,
legumes, nuts and seeds. But, many of the foods that are typical,
or are large components of the western diet are actually quite low in fiber.
Take a look at these. Think about your own diet.
In the last 24 hours have you consumed dairy foods? Meat and poultry, eggs, any
sort of beverage, unless it's 100% fruit juice which doesn't even have a lot of
fiber, most beverages have no fiber, oils and fats have no fiber as well.
You might notice that these food contain protein.
But so do most of these foods. Again, working on the focus to reduce our
animal products, and increase our plant products, not only helps to improve the
fat profile of our diet, but we also can get all of the protein that we need.
Not to mention you get a lot more fiber, when you're eating, from this side, of
the food list. How much fiber a day do we need, well,
there are all sorts of different recommendations, but in the United
States, the Institute of Medicine recommends that for males, if 50 or
younger, they should have 38 grams of fiber, 51 or older, 30 grams of fiber;
females under age 50, 25 grams, and those over, 21 grams.
Why do males generally have higher fiber needs than do females? Well there seems
to be a link between the amount of fiber that individuals eat and their risk for
colon cancer. There's a lot of conflicting data in the
literature, but for the most part, males are at a higher risk for developing colon
cancer. And as a result, their fiber intake needs
are higher. Not to mention, that men, usually have
higher calorie needs, so as a proportion of their calories, you would see that the
total grams of fiber goes up. Since there's all sorts of different
recommendations, we'll kind of pick a target in the middle, which is 30 grams
of fiber a day. And most of us would be well-served to
eat 30 grams of fiber a day. The average American actually only eats
15 grams a day. How can you get 30 grams a day? And how
can you get twice as much as the typical American eats? Well, let's take a look at
this meal plan. Let's say, for breakfast, you have an egg
with a slice of whole wheat toast, and a pear.
You get 8 grams of fiber there. At lunch, you do a cup of lentil soup.
Some brown rice, and a couple boiled greens for another 15 grams.
At snack time, you go for yogurt, which doesn't have any fiber, but if you add a
cup of berries to that, you get 6 grams of fiber.
At dinner, a small portion of chicken breast because there's no fiber in meat,
a 1/2 cup of soba noodles, and a cup of carrots gives you another 4 grams.
And then after dinner, you're hungry again for that ice cream.
No fiber in there. But if you add up your whole day, you see
you got 33 grams of fiber. The key is that every time you eat you
want to have 4, 5 or 6 grams of fiber. If you do that and you eat 3, 4 or 5
times a day, 4 or 5 more so, you're going to be able to meet those 30 gram Per day.
Usually you can't just sit down and eat 30 grams of fiber in one meal.
But if you focus on having whole grains, fruits and vegetables or legumes at every
meal and snack you can easily get to that 30 gramm recommendation.
What does the research say about the role and the relationship between fiber and
heart disease. One of the best known studies, is a
Harvard study from 1986, that looked at almost 44,000 male health professionals,
who were aged 40-75 years old, and didn't have any heart disease or diabetes.
They completed a detailed, 131 item questionnaire, that looked at and
analized the total amount of dietary fiber they were eating.
Eating from food. They were followed at the 6 year period
and there was an inverse association to be found between the amount of fiber that
they took in and their risk for heart attack.
What the researchers found was that a high total dietary fiber intake was
linked to a 40% lower risk of coronary heart disease.
And, furthermore, the researchers found that yes, while fruits and vegetables
were important, that cereal fiber, from grains, was particularly beneficial.
If you're interested in learning more about the role of dietary fiber, in heart
disease, I recommend that you check out these three resources.