|Thin Bones Seen In Boys with Autism and Autism
Results of an early study suggest that dairy-free diets and unconventional
food preferences could put boys with autism and autism spectrum
disorder (ASD) at higher than normal risk for thinner, less dense
bones when compared to a group of boys the same age who do not
The study, by researchers from the National Institutes of Health
and Cincinnati Children's Hospital Medical Center, was published
online in the Journal of Autism and Developmental Disorders.
The researchers believe that boys with autism and ASD are at risk
for poor bone development for a number of reasons. These factors
are lack of exercise, a reluctance to eat a varied diet, lack of
vitamin D, digestive problems, and diets that exclude casein, a
protein found in milk and milk products. Dairy products provide
a significant source of calcium and vitamin D. Casein-free diets
are a controversial treatment thought by some to lessen the symptoms
Funding for the study was provided by the NIH's National Institute
of Child Health and Human Development and National Center for Research
Resources. The research team that conducted the study was led by
Mary L. Hediger, Ph.D., a biological anthropologist in NICHD's
Division of Epidemiology, Statistics and Prevention Research.
"Our results suggest that children with autism and autism
spectrum disorder may be at risk for calcium and vitamin D deficiencies," Dr.
Hediger said. "Parents of these children may wish to include
a dietitian in their children's health care team, to ensure that
they receive a balanced diet."
Dr. Hediger stressed that the current study results need to be
confirmed by larger studies. Until definitive information is available,
however, it would be prudent for parents of children with autism
and ASD to include a dietitian in their care, particularly if the
children's diets do not include dairy products or they are not
otherwise eating a balanced diet, she said.
Because girls are much less likely to have autism or ASD than
are boys, the researchers were unable to enroll a sufficient number
of girls within the short time frame of the study to allow them
to draw firm conclusions. Dr. Hediger added that if a girl with
autism or ASD is not eating diary products or eating a balanced
diet, it would be prudent for a dietitian to be included in her
health care team.
Autism is a complex brain disorder involving communication and
social difficulties as well as repetitive behavior or narrow interests.
Autism is often grouped with similar disorders, which are often
referred to collectively as autism spectrum disorders. The underlying
causes of autism and ASD are unclear. There is no cure for the
disorders and treatments are limited.
When the boys were enrolled in the study, the researchers asked
the boys' parents if the boys were taking over-the-counter or prescription
medications, were taking any vitamin or mineral supplements, or
were on a restricted diet.
During the study, researchers X-rayed the hands of 75 boys between
the ages of 4 and 8 years old who had been diagnosed with autism
or ASD. The researchers then measured the thickness of the bone
located between the knuckle of the index finger and the wrist and
compared its development to a standardized reference based on a
group of boys without autism.
Dr. Hediger said that the research team measured cortical bone thickness.
She added that this procedure was done as a substitute for a conventional
bone scan, which measures bone density. Bone density is
an indication of bones' mineral content. Less dense bones may indicate
a risk of bone fracture.
The researchers used the measure of bone thickness because many
of the boys were unable to remain still long enough for the conventional
scan, which requires individuals to lie immobile for an extended
period of time. To successfully complete the bone scan, many of
the boys would have required sedation — a step the researchers
were reluctant to take for an early study.
The hand X-ray, Dr. Hediger explained, offers an approximate indication
of bone density. She added, however, that because the researchers
were unable to use a conventional bone scan, the results of the
current study should be confirmed by additional studies using conventional
The investigators found that the bones of the boys with autism
were growing longer but were not thickening at a normal rate. During
normal bone development, material from inside the bone is transferred
to the outside of the bone, increasing thickness, while at the
same time, the bones are also growing longer.
At 5 or 6 years of age, the bones of the autistic boys were significantly
thinner than the bones of boys without autism and the difference
in bone thickness became even greater at ages 7 and 8.
The bone thinning was particularly notable because the boys with
autism and ASD were heavier than average and would therefore be
expected to have thicker bones.
The researchers do not know for certain why the boys had thinner
than normal bones. A possible explanation is lack of calcium and
vitamin D in their diets. Dr. Hediger explained that a deficiency
of these important nutrients in the boys' diets could result from
a variety of causes. Many children with autism, she said, have
aversions to certain foods. Some will insist on eating the same
foods nearly every day, to the exclusion of other foods. So while
they may consume enough calories to meet their needs — or
even more calories than they need — they may lack certain
nutrients, like calcium and vitamin D.
Other children with autism may have digestive problems which interfere
with the absorption of nutrients. Moreover, many children with
autism remain indoors because they require supervision during outdoor
activity. Lack of exercise hinders proper bone development, she
said. Similarly, if children remain indoors and are not exposed
to sunlight, they may not make enough vitamin D, which is needed
to process calcium into bones.
The boys in the study who were on a casein-free diet had the thinnest
bones. In fact, the 9 boys who were on a casein-free diet had bones
that were 20 percent thinner than normal for children their age.
Boys who were not on a casein-free diet showed a 10 percent decrease
in bone thickness when compared to boys with normal bone development.
The study authors wrote that bone development of children on casein-free
diets should be monitored very carefully. They noted that studies
of casein-free diets had not proven the diets to be effective in
treating the symptoms of autism or ASD.
Only 9 boys on casein-free diets were available to participate
in the study, Dr. Hediger said. When conducting a scientific study,
it's easier to obtain statistically valid results by studying a
larger number of individuals than with a smaller number of individuals.
However, the dramatic difference in the boys' bone thickness when
they were either on a casein-free diet or an unrestricted diet
and when compared to normally developing bones strongly suggest
that the bone thinning the researchers observed was statistically
The researchers recommended that larger studies be conducted to
confirm their results.
Until those studies can be conducted, Dr. Hediger offered the
following advice: "Our study shows that it couldn't hurt — and
would probably help — if parents of children with autism
or autism spectrum disorder consulted with a dietitian during their
children's routine medical care to make sure that their diets are
General information about autism and ASD is available from the
NICHD's Web site, at http://www.nichd.nih.gov/publications/pubs/autism/overview/index.cfm.
The NICHD sponsors research on development, before and after birth;
maternal, child, and family health; reproductive biology and population
issues; and medical rehabilitation. For more information, visit
the Institute's Web site at http://www.nichd.nih.gov/.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.