Faculty of 1000

Post-publication peer review

Flattery to deceive

Posted by Callum Anderson on 14 April, 2010

Is orange juice a new superfood? Perhaps in some situations it can benefit the body. But the term ‘superfood’ often belies negligible effects in vivo.

A paper by Husam Ghanim, Chang Ling Sia, Mannish Upadhyay, Kelly Korzeniewski, Prabhakar Viswanathan, Sanaa Abuaysheh, Priya Mohanty and Paresh Dandona at the State University of New York at Buffalo (evaluated by our wonderful Faculty of course), suggests that consuming orange juice alongside a fatty, high-carbohydrate meal could limit the adverse effects of all that junk food.

On a slightly related note – while writing this post I was directed by RPG towards a list of The 40 Deadliest Fast Food Meals – and I wonder how much orange juice we might have to drink to alleviate the effects of the top entry? The article clogging, 1300 calorie, 38 grammes-of-saturated-fat-Baconator Triple from Wendy’s!

Right – back to more serious pontification now.

The paper hinges around a comparison of orange juice, water and glucose drink alongside a fatty, high carbohydrate meal and the subsequent production of reactive oxygen species by polymorphonuclear cells, measures of cytokine and endotoxin activation in mononuclear cells, and plasma levels of endotoxin and matrix metalloproteinase.

Bruce Bistrian of the Beth Israel Deaconess Medical Center says in his evaluation

Orange juice reduced the oxidative stress and prevented the formation of pro-inflammatory components, including the increase in plasma endotoxin, compared to either water or glucose. Somewhat surprisingly, there was no increase in plasma glucose with orange juice as found with the meal plus water or the meal plus glucose, despite the substantial carbohydrate and caloric load.

And he added

it is likely that the authors’ suggestion that the mechanism for the antiinflammatory actions was due to the flavonoids naringenin and hesperidin present in orange juice is correct.

So the flavonoids in orange juice may be preventing inflammation after an unhealthy meal, in short limiting the damage.

However, I would not go as far as to suggest that orange juice is particularly brilliant in this respect, especially as the highest concentrations of hesperidin are found in the white parts and peel of oranges, which do not provide a particularly appetising juice. Furthermore, this article suggests that grapefruit provides a significantly higher concentration of naringenin than orange.

But criticism aside; the mention of flavonoids in this paper got me thinking more generally about these so called superfoods. And then more specifically about a press release I saw doing the rounds recently concerning rhubarb. Scientists are inherently aware that test tube or laboratory work does not always transfer into the real world. And the rhubarb press release is a good example of why.

Rhubarb was christened as a new superfruit by some sections of the media due to its high concentration of polyphenols. And the point of these chemicals is that in test tube study, they scavenge free radicals and show other benefits when used in high concentration. But they also have currently undefined mechanisms by which they may reduce the risk of cancer or heart disease. I would be very surprised however if these benefits effectively make the transfer from vitro to vivo. Basically, the concentration levels of ingested polyphenols are usually extremely low, and may be too low in many cases to make any real difference.

A recently published paper by Balz Frei entitled Controversy: What are the True Biological Functions of Superfruit Antioxidants? highlights further problems when flavonoids in particlular find their way into the body. He says

Flavonoids are poorly absorbed into blood and rapidly eliminated from the body; thus, flavonoids have low eventual biological availability.

So really, despite having high levels of helpful chemicals; once ingested, concentration of many of these so called ‘super’ chemicals still lags way behind more common cellular antioxidants.

So eating rhubarb is not going to affect chemical levels for particularly long, because the unique chemicals simply don’t hang around for very long in the body. And this is why I really like the paper by Ghanim et al. Ghanim and his team acknowledge the short bioavaliability of flavonoids and test them in a situation where their effect is clearly measurable against the high calorie meal.

Perhaps I am being too harsh here? In the rhubarb press release, Dr Nikki Jordan-Mahy does admit that the real application of her research lies away from ‘Superfoods’. She says

But if we can extract the polyphenols they may be useful in helping to fight cancer along with chemotherapy.

And this point hits the nail on the head, we need to be thinking how to extract and concentrate these chemicals to make them worthwhile, and in the meantime, the mainstream media needs to understand that positive laboratory tests do not always signify benefits in vivo.

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