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 GLUT5 fluorescent probe fingerprints cancer cells
20.04.2018 | Michigan Technological University

nachricht Scientists re-create brain neurons to study obesity and personalize treatment
20.04.2018 | Cedars-Sinai Medical Center

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: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Getting electrons to move in a semiconductor

25.04.2018 | Physics and Astronomy

Reconstructing what makes us tick

25.04.2018 | Physics and Astronomy

Cheap 3-D printer can produce self-folding materials

25.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>