NEW YORK (Reuters Health) - Breastfeeding is credited with a
long list of benefits, but one downside of extended and
intensive breastfeeding may be a higher risk of cavities in
baby's first teeth, according to a new study.

The more frequently a mother breastfed her child beyond the
age of 24 months during the day, the greater the child's risk of
severe early tooth decay, researchers found.

"The No. 1 priority for the breastfeeding mother is to make
sure that her child is getting optimal nutrition," lead author
Benjamin Chaffee of the University of California, San Francisco
told Reuters Health.

Chaffee completed the study as a doctoral student at the
University of California at Berkeley.

He and his team looked at a possible link between
longer-term breastfeeding and the risk of tooth decay and
cavities in a survey of 458 babies in low-income families in the
city of Porto Alegre, Brazil.

Because the study lasted more than one year, most babies
were eating various kinds of solid food and liquids in addition
to breast milk.

The World Health Organization (WHO) recommends that babies
are fed breast milk exclusively for the first six months of
their lives, with solid foods added to the diet at that point.
However, the WHO also recommends continued breastfeeding up to
age two and beyond, the authors note.

For the study, the researchers checked in on babies when
they were about 6, 12 and 38 months old. At six months, the
study team gathered data on the number of breast milk bottles
the baby drank the day before and any other liquids, like juice.

Two trained dentists examined all of the babies at each of
the visits.

Nearly half of the children had consumed a prepared infant
formula drink by age 6 months, the researchers write in the
Annals of Epidemiology, but very few still drank formula by age
1.

The researchers found that about 40 percent of children
breastfed between ages 6 and 24 months had some tooth decay by
the end of the study. For babies breastfed for longer than two
years and frequently, that number rose to 48 percent.

It is possible that breast milk in conjunction with excess
refined sugar in modern foods may be contributing to the greater
tooth decay seen in babies breastfed the longest and most often,
the authors speculate in their report.

More research is needed to determine what's going on, but
the findings are in keeping with professional dental guidelines
that suggest avoiding on-demand breastfeeding after tooth
eruption, they write.

"There are two aspects of breastfeeding - the actual human
milk, which has some, but very little, ability to promote tooth
decay," said William Bowen, professor emeritus in the Center for
Oral Biology at the University of Rochester Medical Center in
New York.

"The second is the physical aspect of breastfeeding, or even
bottle-feeding, and that's where the problem arrives," he said.

Bowen was not involved in the new study.

When a baby sucks on a mother's breast or from a bottle, the
baby's teeth are sealed off from saliva in the mouth. This
physical barrier prevents the saliva from breaking down
bacteria, and increases the chances of tooth decay, Bowen said.

Even though participants in the study came from poor
backgrounds, "bad habits can form at any socioeconomic level,"
Bowen told Reuters Health.

About 16 percent of babies in the U.S. were still
exclusively breastfed at age 6 months last year, according to
the National Center for Chronic Disease Prevention and Health
Promotion.

The good news, Bowen said, is that it's very easy to clean
an infant's teeth.

A simple wipe in the mouth with a water-dampened cloth or
Q-tip can effectively remove food before the baby's first teeth,
he said, adding: "It's important to get the excess food out of
the mouth."

One not-so-good habit is allowing infants to stay on a
mother's nipple throughout the night, Bowen said. This usually
means very little saliva circulates in the baby's mouth, which
can increase the risk of decay.

The primary caregiver of the baby should also maintain good
dental health because the bacteria that cause tooth decay in a
baby usually come from the primary caregiver, Bowen explained.

The American Academy of Pediatric Dentistry recommends that
parents take their child to its first dental visit when the
first tooth appears, or no later than its first birthday.

"Finding the right age to wean a baby off breast milk can be
a decision made with the support of a pediatrician," Chaffee
said, adding that dental health is one consideration that could
play a role.

Brushing teeth might help, Chaffee said, The study
researchers collected data on tooth brushing habits, but did not
investigate a specific link between cleaning teeth after the
last feeding and caries.

"But anything that removes carbohydrates and sugars from the
oral cavity should help prevent too decay," Chaffee said.