PR release confuses muscle mass and body fat in vitamin D study

Less body fat for toddlers taking vitamin D

Our Review Summary

toddlersThis release summarizes an unexpected finding observed during follow-up of a study that looked at the impact of vitamin D3 supplementation on bone density in young children. The release claims in one section that at 3 years old, children that had been given vitamin D supplementation in infancy (during the ages of 1 month to 12 months old) appear to have reduced body fat and improved muscle mass. In another section, the release states “there were no significant differences in body composition across the different dosage groups” (the children were given either 400, 800, 1200 or 1600 IU/day). The journal article on which the release is based also states that there were no differences in body (muscle) mass between the groups of children given different doses of vitamin D.  The headline and some of the content appear to be discordant with the main findings — that higher vitamin D stores among those given supplements were associated with “around 450 grams less body fat at 3 years of age.” The release also omits cost, harms and funding sources.


Why This Matters

This is an important topic because we are in the midst of a childhood obesity epidemic and need better approaches to prevent childhood obesity. All of the children in this study received vitamin D supplements. Some were given more than others, but the researchers reported no differences in body composition (just body fat) between the various dosage groups. Yet, because the term body composition and body mass are used interchangeably, readers of the release may be left with the idea that giving kids vitamin D supplements reduces body fat and increases muscle mass. (It’s probably important here to note that the term “body composition” refers to both body fat and lean mass. The release several times refers to improved body composition when the study clearly noted there was a correlation only with reduced body fat.) We often see confusion between correlation and causation, but this release appears to wrongly claim causation for changes in body composition where there wasn’t any.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

The release does not mention cost.  A quick online search found that the standard infant dose of 400 IU/day of Vitamin D costs about $10-15 for a three-month supply in the United States. We believe news releases should mention costs, including the cost of relatively inexpensive supplements or unusual foods, with associated health claims. Children growing up in poverty are at particular risk of obesity because their families suffer from food insecurity and often purchase the least expensive (and least nutritional) foods. Expenditures for pediatric supplements for people living well below the poverty level may mean less food on the table.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?


We’ll give this a borderline Satisfactory rating because the release provides a number associated with vitamin D supplements —  450 grams less body fat. However, the release presents some of the findings in a confusing way that could be misleading to readers. It confuses blood levels of vitamin D with doses of vitamin D supplements and it reports that children with higher blood levels of vitamin D averaged around 450 grams (1 pound) less body fat, but the headline says supplements reduce body fat. The researchers clearly stated, “This long-term follow-up of a vitamin D supplementation study in children demonstrates no difference in body composition across any dosage groups (400, 800, 1200 and 1600 IU).” The release notes that “there were no significant differences in body composition across the different dosage groups”, which makes the headline claiming that vitamin D supplements reduced body fat incompatible with what the researchers actually reported.

The release does report that physical activity also made a difference, but did not offer any comparison to the claimed effects of vitamin D levels.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

There is no warning that in rare cases vitamin D overdoses can cause calcium to rise to harmful levels, which can weaken bones and cause kidney stones and other problems. Some of the reported cases have been linked to manufacturing errors which meant the drops given to children contained far more vitamin D than listed on the label.

Does the news release seem to grasp the quality of the evidence?


The release reports that the key strength of this study was that it provided a three-year follow up on children who were given different doses of vitamin D and closely studied during their first year of life. It also notes that the body scans used to assess bone density in the initial study also allowed researchers to measure the children’s muscle and fat mass. However, the release would have been stronger had it noted that the study group was homogeneous (mostly white and healthy). All were carried to term, all were normal size, and 9 out of 10 were breastfed for the first six months. So the researchers can’t say whether their results apply to the population as a whole.

Does the news release commit disease-mongering?


The news release doesn’t hype pediatric obesity.

Does the news release identify funding sources & disclose conflicts of interest?

Not Satisfactory

Even though the researchers did not disclose any conflicts in their journal article and the study was funded by a government agency, the release should have identified the funding source.

Does the news release compare the new approach with existing alternatives?


We’ll give the release a Satisfactory for noting that physical activity is another factor making “a significant difference to the children’s amount of body fat.” The release would have been improved if it had noted that diet, home and family environment can affect the healthy development of young bodies.

Does the news release establish the availability of the treatment/test/product/procedure?


The release notes that vitamin D supplementation is already widely recommended for infants.

Does the news release establish the true novelty of the approach?


The news release claims novelty through this statement: “For the first time, a connection was made between the benefits of achieving healthy vitamin D status during a baby’s first 12 to 36 months and how muscle mass develops.” We agree that the study of infants who received supplementation is the novel piece. However, it’s worth noting that there is a body of literature about the association of low vitamin D levels and obesity in the greater population.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Not Satisfactory

The claims in the headline and lead paragraphs that the study found supplementation reduced body fat and improved muscle-mass development in toddlers are unjustified, because they are simply wrong.

Total Score: 6 of 10 Satisfactory


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