This is a seriously flawed piece of health journalism, one that misinforms the public about a serious and emotional condition. It raises needless anxiety, draws excessive inferences and makes specific treatment recommendations not related to the study under discussion.
1. The study reports an inverse relationship between blood levels of vitamin D at diagnosis of breast cancer and good outcomes. Without clearly explaining that he is reaching well beyond these findings, the medical editor suggests that raising blood levels of the vitamin will have considerable health benefits. The study lacks the power to support that conclusion.
2. The medical editor further suggests that taking vitamin D3 supplements is the most efficient method of raising blood levels. It’s unclear what evidence he bases this on.
3. The segment recommends sunlight exposure as a way to increase blood levels of vitamin D, but does not provide adequate caveats about the risks of overexposure. The medical editor also suggests that even with adequate diet and sun exposure, supplements are likely to be necessary.
There would have been nothing wrong with the medical editor briefly explaining the current findings and their limits–and then saying that he, as a doctor and medical journalist, has studied the issue further and makes the following recommendations. But by conflating the study findings with his opinions and recommendations he borrows the crediblity of the researchers yet oversteps their findings.
The role of vitamin D is an exciting area of study. There is considerable disagreement about whether a cause-and-effect relationship between vitamin D levels and health outcomes has been proven, about whether raising levels has benefits, about the safest ways to raise those levels and what appropriate doses might be.
Viewers should know about these questions. And they inevitably will want to know what they should do until the questions are resolved. But if they are getting recommendations that reach beyond current scientific evidence, they should be made aware of this.
The segment does not report on the cost of either vitamin D generally or D3 specifically.
The broadcast reports that women with low blood levels of vitamin D at diagnosis were 94 percent more likely to have their cancer spread and 73 percent more likely to die than women with adequate levels. But it fails to report underlying risk of death or metastasis.
Seventy-nine percent of women with inadequate D levels at the time of diagnosis, and 69 percent with significant deficiency, were alive without metastsis about 10 years later.
The segment is also silent on the benefits of the treatment recommended. In this case there are no proven benefits of this treatment.
The segment suggests large doses of vitamin D supplements can be harmful. The medical editor specifies what he believes to be a safe range.
But the recommendations regarding sun exposure emphasize the importance of getting adequate exposure without mentioning the considerable, well-established risks of excessive "dosing" of sunlight: skin damage and skin cancer. This is a serious omission.
The study upon which this report is based is a small, observational study that describes a link between blood levels of vitamin D at the time of diagnosis and eventual outcomes. This is not sufficient quality of evidence to justify the segment’s emphasis on supplementation and sunlight exposure as ways to mitigate risk.
By implying–without evidence–that taking vitamin D3 supplements can reduce risk or improve health outcomes, including for breast cancer, the segment invites anxiety on the part of women who are not taking the supplements.
This is essentially a single-source story, with the medical editor providing all information.
In this case, however, the medical editor’s overinterpretation of evidence exposes the risks of depending on a single source, no matter how well-regarded.
The segment fails to discuss other ways to reduce breast cancer risk. A healthy diet, regular exercise and refraining from alcohol can reduce risk modestly. Appropriate screening can improve outcomes.
The segment emphasizes the importance of choosing vitamin D3 supplements, and implies they are readily available.
The segment does not imply that taking vitamin D supplements or increasing sun exposure are novel approaches.
There is no evidence the segment is based closely on a press release.