The
Skinny on Carbohydrates: What They Are and Why We Need Them
For too many Americans, carbohydrates -- or carbs -- have become something
to avoid in the daily diet. But as nutrition experts know, carbohydrate
is an essential macronutrient that provides fuel for the brain and
muscles and contains the fiber needed for proper gut function. Moreover,
many foods primarily composed of carbohydrates have been demonstrated
through numerous scientific studies to lower the risk for certain
cancers, stroke, heart disease and high blood pressure. In addition,
these foods play an important role in the control body of weight,
especially when combined with exercise, which is why the leading medical
and nutrition authorities recommend weight loss programs that are
rich in foods containing carbohydrate, such as from whole grains,
fruits, vegetables and low-fat dairy products.
What exactly are carbohydrates, where are they found and why do our
bodies need them? The following provides a layman's explanation of
this essential macronutrient and its role in the functioning of the
body and in improved health.
What Are Carbohydrates?
Carbohydrates are in a wide variety of foods and are one of the three
major macronutrients that supply the body with energy, fat and protein
being the others. But unlike fat and protein, carbohydrates are efficiently
converted into glucose, which is used directly by the muscles and
brain. That is why the Institute of Medicine (IOM), part of the National
Academy of Sciences, recently issued a recommendation that children
and adults get a minimum of 130 grams of carbohydrate a day to maintain
maximum brain function. This amount is more than six times more than
what the initial phase of the Atkins Diet allows (20 grams of carbohydrate
a day).
Besides being the most easily accessible energy source for muscles
and organs of the body, carbohydrates play an important role in the
construction and maintenance of the body's tissues, organs and cells,
including nerve cells. At the same time, carbohydrates are found in
a wide range of foods that bring a variety of other important nutrients
to the diet, such as vitamins and minerals, phytochemicals, antioxidants
and dietary fiber. A diet high in these nutrients has been associated
with a lower risk for certain cancers, cardiovascular disease and
stroke, and diabetes, among other medical conditions.
Carbohydrates are grouped into two main categories: 1) simple carbohydrates,
which contain simple sugars, such as glucose and fructose, found in
fruits, berries, some vegetables, table sugar and honey; and 2) complex
carbohydrates, found in many plant-based foods, whole grains and low-fat
dairy products. For optimal health, nutrition and public health authorities
recommend consuming a wide range of carbohydrate-containing foods
with an emphasis on fruits, vegetables, whole grains and low-fat dairy
products. For both weight control and good health, experts advise
caution in over consuming processed foods where sugar is added, such
as soft drinks, pastries and other sweets.
Carbohydrates and Improved
Health
There have been major advances in the understanding of how carbohydrates
influence nutrition and promote better health. Of special significance
is the role that carbohydrates play in gut function, disease prevention
and body weight regulation.
Because many carbohydrates contain dietary fiber, one of the most
important benefits of eating carbohydrates is the health effects associated
with consuming fiber-rich foods. Commonly called roughage, fiber is
an indigestible complex carbohydrate found in plants and has no calories
because the body cannot absorb it. Fiber-containing carbohydrates
come in two forms -- water-insoluble and water-soluble -- based on
their physical characteristics and effects on the body. Each form
functions differently and provides different health benefits.
Although most consumers just associate fiber with preventing constipation,
a high fiber diet has been linked with a lower risk of heart disease
in a large number of studies that have followed people for many years.
In a Harvard study of more than 40,000 male health professionals,
researchers found that a high fiber intake reduced the risk of coronary
heart disease by 40 percent, compared to a low fiber intake. Fiber
has also been linked with a reduced risk of diabetes, diverticular
disease and may be protective against colon cancer. Moreover, fibers
called cellulose and hemicelluloses take up space in the GI tract
without yielding calories, promoting the feeling of fullness, which
is helpful to those watching their weight.
Carbohydrates prevent disease in other ways besides being the sole
source of fiber. Packaged along with fiber in fruits and vegetables
-- which are primarily carbohydrates -- they are rich in antioxidants
and contain a number of phytochemicals that have been linked to a
lower risk of certain cancers, stroke, heart disease and high blood
pressure.4 Based on an extensive review of more than 4,500 research
studies around the world, in 1997, the American Institute for Cancer
Research (AICR) and the World Cancer Research Fund issued the expert
report, Food, Nutrition and the Prevention of Cancer: a global perspective,
which concluded that "a simple change, such as eating the recommended
five servings of fruit and vegetables each day, could by itself reduce
cancer rates more than 20 percent."According to the research
conducted to date, carotenoids and other antioxidants and various
phytochemicals that are packaged in carbohydrate-containing foods
are key players in reducing cancer risk and more likely, it is the
combination of these compounds that confer protection.
Besides protecting against cancer, researchers have also found that
diets rich in fruits and vegetables can lower the risk of heart disease
and stroke. One large Harvard study of both men and women found that
those who ate eight or more servings of fruits and vegetables a day
had a 20 percent lower risk of heart disease than those who ate fewer
than three servings daily. Another Harvard study of nearly 80,000
women and 40,000 men found that people who ate five servings of fruits
and vegetables a day had a 30 percent lower risk of ischemic stroke,
the most common type of stroke.
The other important health benefit associated with carbohydrates is
regulating body weight, an area of research that seems to have gotten
lost in the low-carb craze. According to the recent report from the
World Health Organization (WHO) and the Food and Agriculture Organization
of the United Nations, Carbohydrates in Human Nutrition, people eating
a diet high in fruits, vegetables, whole grains and low-fat dairy
products are less likely to accumulate body fat than those following
a low-carbohydrate, high fat diet.8 The WHO report lists three possible
reasons:
* High carbohydrate diets have lower energy density than their counterparts,
meaning that carbohydrates have less calories weight for weight than
fat;
* Studies have found that both in the form of starch and sugars, carbohydrates
aid satiety, which leads people to eat less;
* Research also shows that very little dietary carbohydrate is converted
to body fat mainly because it is a less efficient process for the
body. Instead, most carbohydrates are burnt for fuel while the fiber
in carbohydrate foods is not digested at all.
How Much Do We Need?
Recognizing the many health benefits associated with carbohydrates
-- and especially diets rich in fruits, vegetables, whole grains and
low-fat dairy foods -- the Dietary Reference Intakes Report issued
by the Institute of Medicine in 2002 recommended that Americans get
the majority of their calories a day from carbohydrates. Specifically,
the IOM report states that:
* Adults should get 45 percent to 65 percent of their calories from
carbohydrates, 20 percent to 35 percent from fat, and 10 percent to
25 percent from protein.
* The minimum amount of carbohydrate that children and adults need
for proper brain function is 130 grams a day.
* Added sugars should comprise no more than 25 percent of total calories
consumed. The IOM report was designed for normal weight individuals;
overweight people need far less.
* For adults 50 years and younger, the recommended total intake for
dietary fiber is 38 grams for men and 25 grams for women. For those
over 50, it is 30 grams and 21 grams respectively.
Summing It Up
For maintaining good health and weight control, nutrition and public
health authorities agree that the bulk of a person’s calories
should come from carbohydrates and especially, from fruits, vegetables,
whole grains and low-fat dairy products. Of equal importance, experts
stress the importance of variety so that people will have access to
all the essential nutrients and fiber available through carbohydrate-containing
foods.
By Partnership for Essential Nutrition
