Fish Intake Biomarker

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

One of the difficulties in doing nutrition research is to try to accurately assess what people eat. Not what they say they eat, or not what we eat during a three-day food record where someone basically follows us around with a clipboard, but what we actually eat, on average, when no one’s looking.

That’s why scientists love biomarkers—things you can actually physically measure in the blood or urine to tell you how much of a certain food someone is eating.

So, for example, there are these unique phytonutrients in cruciferous vegetables—like broccoli, kale, collards—that help prevent cancer. But you can’t just ask people if they eat their greens, because people want to look good, and so, they fib a little.

Well, not any more, though; now, there’s a urine test you can do to see if people are actually telling the truth. Some employers test for drugs; now you can test for greens—it’s like a broccoli breathalyzer!

The important thing is that now researchers can more accurately measure intake. Last year, scientists discovered a biomarker for fish consumption—like a tuna test. They take a sample of your blood, and without asking you a single question about your diet, can tell how much fish you’ve been eating.

What’s the biomarker? Arsenic. Arsenic turned out to be the best indicator. Blood arsenic appears to be a useful biomarker for total fish and seafood intake.

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• S. J. Genuis. Nowhere to hide: Chemical toxicants and the unborn child. Reprod. Toxicol., 28(1):115-116, 2009.
• M. Kristensen, K. S. Krogholm, H. Frederiksen, S. H. Bugel, and S. E. Rasmussen. Urinary excretion of total isothiocyanates from cruciferous vegetables shows high dose-response relationship and may be a useful biomarker for isothiocyanate exposure. Eur J Nutr, 46(7):377-382, 2007.
• A. L. Brantsaeter, M. Haugen, Y. Thomassen, D. G. Ellingsen, T. A. Ydersbond, T. A. Hagve, J. Alexander, and H. M. Meltzer. Exploration of biomarkers for total fish intake in pregnant Norwegian women. Public Health Nutr, 13(1):54-62, 2010.

Image thanks to Joseph via Flickr.

• animal products
• arsenic
• broccoli
• collard greens
• cruciferous vegetables
• fish
• fish oil
• greens
• kale
• seafood