DR.DENNIS BIER & USDA DIET GUIDELINES
Director of the Children's Nutrition Research Center, Baylor
University, Houston Texas
by Sean Henahan, Access Excellence
Every five years the USDA releases new dietary
guidelines. Every time they do this the guidelines are different
from the ones before. This is because a panel of experts from
across the country considers thousands of new studies and forms
a consensus based on that data. I spoke with one of the panel
members, Dennis Bier, M.D. about the new guidelines. Check the
resource guide at the end of the interview for more
Would you tell us something about the process by which the new
guidelines were determined?
A: The dietary guidelines are regulated by
public laws that require the USDA and Department of Health and
Human Services to revaluate the previous guidelines and
determine whether changes are needed based on new scientific
information. These agencies, with advice from government,
scientific, industry and consumer groups, appoint a committee of
leading experts from around the country representing a variety
The 11 member committee met several times to discuss whether the
scientific information concerning human nutrition had changed
since the last guidelines. The committee considered large stacks
of scientific literature that had appeared since the last
guidelines. The committee also received written testimony from
more than 200 scientific groups, consumer groups, industry
sources and other interested parties. Public testimony was also
The committee, which is made up of people with a broad range of
opinions, then argued the issues to a point where a consensus
was formed. I think it is an extraordinarily open and fair
The guidelines appear to put a strong emphasis on the benefits
of antioxidant vitamins. While recommending nutritional sources
of antioxidants, the guidelines stop short of recommending that
most Americans take vitamin supplements. Why is this?
A:In the last five years there has been a vast
amount of new data about the potential value of antioxidants in
terms of aging, cancer and prevention of chronic disease.
Antioxidants are required by all cells, performing a metabolic
function of disposing of oxygen free radicals. It is clearly
essential that we get enough of them. What we don't know with
any degree of certainty is how much added health benefit there
is from taking more than the essential amount. Further, it is
not even entirely clear what the minimally essential amounts of
some antioxidant compounds are. There are many new antioxidants
recently identified in foods that we are only beginning to learn
about. So it is very difficult to recommend that any one eat
lots of the few antioxidants available as supplements, since the
preponderance of available scientific information does not point
convincingly to an added benefit over consuming apparently
adequate amounts in a balanced diet .
The reason for recommending food rather than supplements is that
there are numbers of antioxidant compounds in food that you
won't get by taking specific antioxidant supplements. So the
committee believes that we don't know enough to be able to
recommend one antioxidant over another or the proper
proportions of a mixture of antioxidant supplements. The prudent
course is to eat food that contains antioxidants in the amounts
and proportions occurring in nature, optimizing your diet that
The guidelines provide very little endorsement for taking
supplements of any kind. Is this the same situation?
A:The committee's position is that if you eat
an adequate diet there is limited information except in selected
groups that supplementing nutrient intake, over and above that,
confers any particular benefit. Taking pills alone leaves out
many of the known and unknown nutrients and non-nutrient
components in foods that are known or believed to be helpful.
For example, an athlete may excessively load up on a diet
composed of virtually all carbohydrates, while reducing his or
her intake of essential fatty acids that occur in some fats and
the essential amino acids that occur in proteins. The athlete
may take vitamin supplements thinking this will optimize the
diet, but in fact it will not since the essential fatty and
amino acids will still be missing.
We also said that taking supplements within the range of the RDA
(recommended daily allowance) is not considered to be harmful.
It is in the area of mega-supplements where there may be
One area that should be strongly emphasized is folic acid in
women of child-bearing age. This message has not reached the
general population. There are very clear data that adequate
folate intake prior to and at the time conception as well as
during the first month of pregnancy (when many women do not yet
know they are pregnant) will reduce the incidence of neural tube
defects in the infant's developing brain. Therefore it is
essential for young women to make sure they are receiving enough
folic acid in their diets. If they are not, or if there is any
question about their intake level, they should be sure to take a
folic acid supplement of 400 micrograms daily.
Another example of where supplements may be required would be
elderly shut-ins who are not getting much sunlight. They may
need supplemental vitamin D to help maintain bone strength.
similarly, pregnant women with poor iron intake may require iron
The guidelines are designed for people over two year of age. Are
there any guidelines for those under two years?
A:There are no federal standard dietary
guidelines for children under the age of two. Indeed, one of
the recommendations of the dietary guideline advisory committee
was that this issue should be considered within the next five
year period before the next issue of the guidelines is due.
The guidelines emphasize that any ethnic diet can be healthy.
Why the new emphasis on ethic diets?
A:The guidelines recognize that America is
becoming more ethnically diverse. Most ethnic diets contain a
large variety of healthy food choices, and we wanted to
The guidelines also for the first time say that a vegetarian
diet is OK, but with certain caveats.
A:The primary concern about vegetarian diets
for kids or adults are B12, which can only be obtained from
animal sources, and calcium and vitamin D, which most Americans
obtain from dairy products. One must also make sure to get
enough of the essential minerals, particularly iron and zinc.
While these minerals are present in plants, there is some
question about the bioavailability, e.g. iron in meat is
absorbed into the body considerably better than iron in plants.
But there is no question that children can grow and develop
normally on a vegetarian diet as long as the nutrients content
The new guidelines talk a lot about fat, cholesterol and body
weight. How do these fit together?
A:The guidelines have much to say about fat in
the diet, controlling fat intake, maintaining weight, and
increasing physical activity. A large amount of the calories in
our diet come from foods containing fat. One of single most
important messages in the new guidelines concerns the importance
of maintaining body weight and increasing physical activity. It
is extremely important that young people leaving high school
should realize that they should not continue getting fatter, but
should maintain physical activity and watch their weight.
The other concept we tried to emphasize, is that there are good
reasons to limit fat intake. Often the foods that contain
saturated fats also contain cholesterol. Saturated fat has an
independent effect on what happens to blood cholesterol. By
watching the foods that contain both, you tend to reduce the
intake of both. But you also have to be aware that even after
reducing fat intake, you still have to watch your total caloric
What is the consensus on the relationship between eating sugar
A:We haven't heard the last of this topic. Some
people think high sugar intake promotes attention deficit
hyperactive disorder while others are not convinced. The
committee looked at a lot of blinded studies considering this
question and the majority have failed to show any effect of
sugar on hyperactive behavior. Thus, it is hard to confirm this
presumed effect of sugar in carefully controlled clinical
studies. However, I assume we have not heard the last of this
issue yet since many parents remain convinced that there is an
effect. It is hard to confirm this effect in a clinical study.
What other nutrition issues do you see being considered prior to
the next guidelines five years from now?
A:The guidelines are the basis for many
government educational and implementation tools like the food
guide pyramid. The USDA has not yet decided whether the new
guidelines have changed enough to require changes in the
pyramid. For example, a representative of the National Bean
Council came and testified before the committee. They reaffirmed
that beans are vegetables and should be placed in the broader
part of the pyramid containing vegetables, rather than near the
narrow tip of the pyramid in the meat group, where beans are now
included since beans, like meat, are a good alternate source of
protein. this is a logical position and the new dietary
guidelines emphasizes the dual role of beans.
Some of the continually developing issues of antioxidants will
also become more important as data from new studies become
available. another area where discussion is likely concerns
specific population groups. for example, guidelines for elderly
adults and children may be developed. the various roles of
salt, sugar and alcohol in the diet are also likely to continue
to receive attention. these issues will surface again as new
scientific information becomes available to the committee
charged with formulating the next guidelines in the year 2000.
Related information on the
Internet (updated: August 2003)
USDA's Food and Nutrition Information Center
Guidelines- complete text
for Nutrition Policy and Promotion