No, that’s not what the headline was on the front page of the Weak-end Herald today – it was considerably more alarmist:
An expectant mother could be putting her unborn child at risk by drinking as little as three glasses of juice a day or eating five apples.
Scientists at the University of Auckland’s Liggins Institute have found a connection between sugars such as fructose and impaired fetal development.
You only learn that this study involved rats in paragraph seven…
Now, I’m not one of those strange people who think that animal studies are a waste of time. Rats are useful little creatures in experimental research. Their physiology is reasonably similar to a human’s. They have short life cycles, meaning we can easily work out if their lives are shortened by our experiments. And, in general, animal rights people do not go all gooey over them because they are not endangered and not cute. This means that scientists can do relatively disgusting things with rats that they could not do with dogs, cats or chimps. Above all, working with rats is relatively cheap.
However, rats are not humans. This means that a result we obtain experimenting on rats really does need to be verified in humans. You can’t just extrapolate.
In the study in question, (Vickers MH, Clayton ZE, Yap C, and Sloboda DM Maternal Fructose Intake during Pregnancy and Lactation Alters Placental Growth and Leads to Sex-Specific Changes in Fetal and Neonatal Endocrine Function Endocrinology 152: 0000—0000, 2011 – publication ahead of print), the female offspring of pregnant rats fed a diet of 20% fructose had raised plasma leptin, fructose, and blood glucose levels at birth indicating a possible predisposition to both obesity and, eventually diabetes. This sounds considerably less scary than 5 apples a day (the equivalent of 20% fructose) is linked to fetal harm.
Similar results have been obtained before in rat studies but this particular study models a more “normal” consumption level of fructose (previous studies were of 50% and higher levels of fructose in the diet). While this is certainly something that needs further study, we are a long way from extrapolating this to humans. It may be that rats are particularly sensitive to fructose in their diet, or that they are not as efficient as humans in metabolising it. It may be that the source of the fructose is important, with apple consumption being better than drinking fructose-laden corn syrup. There are many factors that could lead to an entirely different result in humans.
The authors of the study cite a Finnish cohort study that found that an increase in sugar- sweetened beverages from childhood to adulthood was associated with being overweight in women but not men, bolstering the sex specificity of their findings but not otherwise adding to the idea that fructose may case metabolic problems in children. There are plenty of other studies ably demonstrating that excessive sugar consumption in childhood and adolescence predisposes people to develop diabetes in adulthood. There are plenty of reasons to moderate our sugar intake. But to blindly suggest that pregnant woman maybe putting their babies at risk by eating fruit is dubious in the extreme. Unfortunately that is exactly the message that mums will get from this article. After all, it’s on the front page. It must be important.
I can understand the desire of researchers to get their research in the news. Generate enough concern about something and you guarantee that you will get sufficient funding to continue the research to the next level. But this type of premature ejaculation of scientific results panders to excitable journalists looking for sensational headlines and predisposes them to generate messages that are entirely unhelpful, if not dangerous. I can guarantee you I am going to be spending valuable consultation time with pregnant women explaining why it is safe to eat apples, rather than spending it addressing their real concerns. Worse still, there will be pregnant women who stop eating fruit altogether, putting themselves at possible risk of vitamin deficiencies.
And all because scientists want funding and journalists want headlines. How sad.