Do Supplements Augment or Replace Meals?

Source: Tufts University
June 20, 2002 (Reviewed: June 29, 2004)

In theory, nutritional supplements such as Ensure, Boost, and Sustacal offer an easy way to increase calorie and protein intake in debilitated seniors who do not eat enough to maintain their body weight. But just prescribing these formulas isn't enough, as a study in the American Journal of Clinical Nutrition shows, since they may replace - rather than supplement - the calories consumed at meals.

Researchers at the St. Louis Health Sciences Center in Missouri recruited 30 healthy men and women; half were over age 70 and half were between the ages of 20 and 40. Two mornings a week for several weeks, each consumed one of four liquids: 300 ml of water or a dietary supplement that supplied 300 calories as carbohydrate, protein, or fat. This was followed immediately by a meal. The study was a within-subject, repeated-measures design, so participants served as their own controls.

In the next phase of this study, the participants again consumed the liquids, but then waited for at least one hour before they ate their meal. In both phases, participants rated how hungry they were before the meal was served. The researches then determined intakes of carbohydrate, protein, fat, and total calories consumed by the participants at each meal.

Timing is everything

As might be expected, all participants ate less when consumption of one of the calorie-containing beverages was followed immediately by a meal. This effect was more pronounced in seniors than in the younger participants. On the other hand, energy and micronutrient intake was higher in all participants when the meal was delayed by an hour.

These results seem obvious - everyone is less hungry at mealtime when they eat something immediately before the meal - but this study highlights a common problem in how liquid nutritional supplements are used in a clinical setting. Too often, the supplements are consumed in place of - rather than addition to - regular meals.

Why do seniors eat less?

Several factors work against some seniors' ability to consume an adequate amount of food. The most obvious is chronic illness, which can sap both appetite and the energy needed to prepare meals. The senses of taste and smell decline with age, and certain medications can make this problem worse, making foods - including nutritional supplements - "taste funny." To compound the problem, gastric emptying slows with age, so not only are older people often satisfied with less food, it takes them longer to get hungry again after a meal.

Points to consider

• In prescribing a supplement for a patient, ask that it be given at least one hour before or after meals.
• Work with a dietitian or other healthcare provider to insure that the patient is able to consume the supplement and still eat an adequate amount of food at mealtime.
• Nutrition supplements come in a variety of flavors and can be served chilled or at room temperature. A dietitian can help the patient find a flavor they can tolerate.

Source

• Effect of liquid dietary supplements on energy intake in the elderly. MM. Wilson, R. Purushothaman, J. Morley, Am J Clin Nutr, 2002, vol. 75, pp. 944--947

Related Links
Weight Loss a 'Slippery Slope' for Seniors
Nutrients May Enhance Immune Function in the Elderly
Mini site: International Academy of Nutrition and Aging
Mini site: Basel Geriatric Corner
To quickly access additional accurate information on this and other nutrition-related topics, visit Tufts University's Nutrition Navigator

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