Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nutritionists wake up to mealy methods

23.04.2002


Fortification and false memory could foil food and drug trials



When nutritionist Andrea Pontello went shopping for apple juice she got a "wake-up call". Apple juice is normally low in vitamin C, but she found that 9 out of 11 brands had been boosted with additional vitamins.

Supplementation could scupper clinical trials for antioxidants, she realized, if participants’ intake of vitamins C and E from fortified foods is not taken into account.


Antioxidants mop up reactive molecules that damage cells. They are being widely tested for their benefits on conditions from Alzheimer’s disease to ageing.

Pontello, of the University of California, Irvine, went back to the grocery store to scan more food labels. Oatmeal, yoghurt, eggs, salad dressing, even mineral water can be loaded with vitamins at levels equivalent to those in a vitamin supplement, she told the Experimental Biology 2002 meeting in New Orleans on Saturday.

Participants in trials are normally asked to eliminate supplements from their diet. But one portion of fortified cornflakes contains 60 milligrams of vitamin C, Pontello found, and a fruit-juice smoothie packs up to 250 milligrams. People on a normal diet might unknowingly reach or exceed the 60 milligrams of vitamin C in a typical multivitamin pill, thus confounding trial results.

"Investigators need to use better methods to see what people are taking in," Pontello said. The extent of the fortification phenomenon is so far unclear.

But nutrition researchers at the New Orleans meeting were unfazed by the potential of such effects to scupper their studies. "We will not negate as much as reanalyse the data," says Michele Forman, who studies clinical nutrition at the National Cancer Institute’s Center for Cancer Research. Antioxidant trials carried out before food supplementation became widespread are still valid, she points out.

Factoring in the range of antioxidants and their levels in different food brands will need "a tremendous amount of effort", adds Forman. It may be an effort that researchers have to make.

Forgotten food

Nutrition trials are also complicated by participants under-reporting what they eat. Amy Subar, also of the National Cancer Institute, announced the results of an international project to assess the scale of the problem.

Around a third of men and women aged 40-69 who were assessed in suburban Maryland significantly under-reported their energy intake, the project found. The study is the first large-scale effort to compare the food consumption described in questionnaire responses with an unbiased measure using ’biomarkers’.

Urinary nitrogen levels reveal protein intake. Measuring the amount of oxygen and hydrogen isotopes left in urine after drinking labelled water relates to the metabolic turnover of these isotopes, and can be used to calculate total energy expenditure.

Researchers already try to correct for under-reporting using corroborating interviews that prompt people to recall food intake. But the new study shows that this method does little to circumvent the problem.

Studies that have tested the relationships between diet and types of cancer might be affected, said statistician and team member Victor Kipnis of the National Cancer Institute. "The real effect could be obscured." But specific biomarkers for key diet components such as fat, fibre, and fruit and vegetables do not yet exist.

Future studies may have to adjust for under-reporting, suggests Forman.

HELEN PEARSON | © Nature News Service

More articles from Health and Medicine:

nachricht Organ-on-a-chip mimics heart's biomechanical properties
23.02.2017 | Vanderbilt University

nachricht Researchers identify cause of hereditary skeletal muscle disorder
22.02.2017 | Klinikum der Universität München

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>