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TalkingNutrition

Providing perspectives on recent research into vitamins and nutritionals

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Eat More Fiber and Use Clinical Measurements to Monitor Health

By Michael McBurney

In a JAMA viewpoint, the opening sentence claims the US obesity epidemic costs $190 billion in health care expenditures annually. That is a tremendous cost to society and individual quality of life. Malik and associates explain the new changes to the nutrition and supplements facts panels along with the new Reference Amounts Customarily Consumed (RACCs) and serving sizes. The authors write ‘Careful monitoring of how food manufacturing changes in response to the label changes will be an important step in ensuring nutritional quality of food products.’

This is true. The Branded Food Products Database, being developed as a partnerships USDA/ARS, ILSI North America, and the ATiP Foundation, with the voluntary participation of the food industry, will expand the USDA National Nutrient Database of 8,000 foods. This database will help us to monitor changes in the foods available to consumers. However, food databases do not represent food intake.

Systematic errors in measurement of dietary patterns skew nutrient intakes and distort associations between diet and disease. Body weight, body mass index, or body fat content can be accurately measured and associated with the prevalence of disease or health care costs. The impact of changes in  body weight, or hypertension, or elevated total serum cholesterol on disease prevalence and health care costs can be measured. However, dietary associations (added sugar intake, trans fatty acid intake, etc) with any outcome should be considered with suspicion. Why? Because people do not accurately report their food intake or physical activity.

In their viewpoint, Malik et al write “Some food manufacturers have managed to exploit the food label in ways not addressed in the current revision. For example, purified additives such as inulin and cellulosic fibers (“functional fibers”) are allowed to be included in the “fiber” line to convey a healthy product, even though there is little evidence that they have the same benefits as fibers contained in foods.

I disagree. Food companies are not being exploitive by declaring soluble (inulin) or non-soluble (cellulose) fiber on a nutrition label. They are following the law [21 CFR 101.9(c)(6)(i)] to properly label sources of dietary fiber. There are FDA approved health claims for ‘functional fibers’ because evidence exists they do affect the risk of coronary heart disease (eg. oat beta-glucan, barley betafiber, and psyllium husk).

In 1929, Whitacre and colleagues showed that the addition of cellulose to a human diet affected nitrogen balance. utilization. Although the analytical approaches to measure dietary fiber and its constituents in 1929 are questionable, cellulose is an important contributor to the laxative action of bran. It is ridiculous to vilify companies for adding cellulose, or any other component of dietary fiber (hemicellulose, inulin, beta-glucan, etc) to increase the fiber content per serving.

Eat more fiber. The recommended fiber intake is now 28g per day for adults. Read labels to make healthier food and supplement choices. Ask your doctor for clinical measurements (weight, blood pressure, blood glucose, blood cholesterol, vitamin concentrations) as these are the only reliable tools to monitor nutritional status.

 Main Citations

Malik VS, Willett WC, Hu FB. The revised Nutrition Facts Label: A step forward and more room for improvement. 2016 JAMA doi: 10.1001/jama.2016.8005

Markussen MS, Veierod MB, Ursin G, Andersen LF. The effect of under-reporting of energy intake on dietary patterns and the associations between dietary patterns and self-reported chronic disease in women aged 50-69 years. 2016 Br J Nutr doi: 10.1017/S000711451600218X

Other Citations

Cawley J, Meyerhoefer C. The medical care costs of obesity: an instrumental variables approach. 2012 J Health Econ doi: 1016/j.jhealeco.2011.10.003

Whitacre J, Willard A, Blunt K. Influence of fiber on nitrogen balance and on fat in the feces of human subjects. 1929 J Nutr 2:187-195

Falcon-Lesses M. The cause of the laxative action of bran. 1929 J Nutr 2:295-310

Marlett JA, McBurney MI, Slavin JL. Position of the American Dietetic Association: Health Implications of Dietary Fiber. 02 JADA doi: 10.1016/S0002-8223(02)90228-2


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