Packaged and processed foods sold in the United States started carrying standardized nutrition labels in 1994 when the Nutrition Labeling and Education Act (NLEA) took effect. The major goal was to increase access to nutrition information and improve consumers' ability to make healthful food choices. Since NLEA took effect, technological change has introduced new sources of nutrition information and the consumption of food away from home has continued to increase. But have these measures been effective?

A new report examines how the consumers' use of nutrition labels have changed over the decade by looking at the trend in use of various nutrition label components and demographic groups. The U.S. experience may help policymakers in other countries who are considering mandatory nutrition labeling to achieve public health goals.

The study reveals that in the decade from 1996 to 2006, consumer use of nutrition labels declined. It declined 3% for the Nutrition Facts panel, 11% for the ingredient list, and 10% for the panel's information about calories, fat, cholesterol, and sodium. In fact, only fiber and sugar did not decline over the 10-year period. Sugar held steady while fiber increased by 2% - a telling result.

The decrease in use of the nutrition label was greatest for individuals in the 20-29 year-old bracket.

If you are wondering how the government possibly misunderstood the information desires of consumers, you need look no further that the new UK Food Standards Agency (FSA) report "Consumer Priorities for Sustainable Development "

Not satisfied with spontaneous answers to questions about what is important to consumers when buying food, the FSA researchers prompted them with specific responses. They then combined both the spontaneous and prompted answer for the final result. For example, only 7% of UK consumers were concerned with salt, but after prompting, an additional 27% said they were concerned. This resulted in a grand total of 34%. Talk about fudging!

Is it any wonder we always fail to recognize the consumers' genuine desires?

The New England Journal of Medicine recently published a long-term follow-up study to determine the impact of tight control over blood pressure among patients with Type II Diabetes. Researchers at the United Kingdom Prospective Diabetes Study (UKPDS) wanted to see whether the risk reductions achieved during periods of tight control over blood pressure would be sustainable after those controls were relaxed.

Out of 5000 patients with newly diagnosed type II diabetes, they randomly assigned more than 1000 that had hypertension to either tight or more relaxed blood-pressure control regimes. Patients with blood pressures greater than or equal to 160/90 mm Hg were randomly allocated to tight-control, aiming for less than 150/85 mm Hg with either an angiotensin-converting enzyme inhibitor or a Beta-blocker or to less-tight-control aiming for less than 200/105 mm Hg. Patients who underwent post-trial monitoring were asked to attend annual UKPDS clinics for the first 5 years, but no attempt was made to maintain their previously assigned therapies.

What was the result? After the trial, blood-pressure levels fell in the less-tight-control group and rose in the tight-control group, with no significant differences between the groups after 2 years. In line with this equalization of blood pressures, there were no significant risk reductions observed between the groups 10 years after the trial.

Differences in blood pressure between the two groups during the trial disappeared within 2 years after termination of the trial. Significant relative risk reductions found during the trial for any diabetes-related end point, diabetes-related death, microvascular disease, and stroke in the group receiving tight, as compared with less tight, blood-pressure control were not sustained during the post-trial follow-up.

For more than a quarter of a century, the Department of Health and Human Services and the Department of Agriculture have jointly published a new version of the "Dietary Guidelines for Americans" every five years. In 2010, the sixth edition of this publication will come out.

With reference to the consumption of salt, the Dietary Guidelines has served the public poorly. The fact of the matter is that the figures are based entirely upon expert opinion, not scientific trials. This was confirmed in the paper delivered at the Institute of Medicine workshop "The Development of DRIs 1994-2004: Lessons Learned and New Challenges" held in Washington September 18-20, 2007 by Dr. Peter Greenwald, Director of Cancer Prevention at the National Cancer Institute of the National Institutes of Health . Dr Greenwald described how most of the figures behind the recommended dietary intakes were based upon expert opinion - the lowest quality of medical evidence - rather than randomized controlled double blind clinical trials - the highest level of evidence.

The next iteration of the Dietary Guidelines will be the sixth in the series. Are we destined to continue basing our dietary recommendations on the lowest level of evidence? What would happen if Americans actually adhered to the dietary guidelines? The only evidence we have thus far is not particularly reassuring. In two studies on healthy young adults, carried out in very different geographic locations, college students were limited to 2300 mg Na/day - the Upper Limit for sodium recommended by the Institute of Medicine (1), (2). In both cases, all the students taking part in the trial experienced elevated aldosterone levels, and in the case of the Shapiro et al. study, they all showed evidence of arterial stiffness.

These are the only experimental results we have relating to the Institute of Medicine recommendations for sodium intake. Surely, it behooves us to test whether the IOM's recommendations are safe for Americans or not. If they once more appeared in the Dietary Guidelines, based solely on expert opinion, consumers would be justifiably bound to abandon confidence in the science behind these recommendations.

It is time to step up to the plate and have the Institute of Medicine recommendations tested experimentally

We need to establish a trial with a significant group of healthy young adults who are comprehensively counseled on how to limit their sodium intake to 2300 mg/day. As a lead-in to the trial, their baseline blood pressures, 24-hr urinary sodium, and plasma renin and aldosterone levels would be accurately determined. Once the trial began and the young adults maintained their sodium intakes at 2300 mg/day, these parameters will be checked on a weekly basis. The trial will continue for 30 days and a final analyses of blood pressures, urinary sodium, renin and aldosterone would be taken.

Such a trial would give us an excellent understanding of the impact of maintaining a consumption level of 2300 mg/day of sodium or less - on blood pressure as well as renin/aldosterone levels. It would be the first large-scale trial into the effect of adhering to the IOM recommendation for sodium and will be critically important in establishing the next edition of the Dietary Guidelines. Such a trial would not be overly costly and would, for once, remove considerable doubt regarding the validity of the IOM recommendations.

(1) Kodama N, Nishimuta M, Suzuki K., "Negative balance of calcium and magnesium under relatively low sodium intake in humans," J Nutr Sci Vitaminol (Tokyo), 2003, Jun;49(3):201-9.

(2) Shapiro, Y., Boaz, M., Matas, Z., Fux, A., & M. Shargorodsky, "The association between the renin-angiotensin-aldosterone system and arterial stiffness in young healthy subjects," Clinical Endocrinolog,. 2008 Apr;68(4):510-2.