One of my adult patients drinks diet cola all day long. What should I teach my patient about this choice of beverages?—S.F., N.Y.
Mary Ann Yantis, PhD, RN, and Kate Hunter, RD, LD, reply: Many people believe that diet soda is healthier than the regular, calorie-containing kind, but the literature isn't clear on this. The FDA, which regulates artificial sweetener use in the United States, currently considers the use of aspartame, sucralose, saccharin, and acesulfame potassium to be safe and not linked to the incidence of cancers.1 (Because stevia is classified as an herbal, it's not regulated by the FDA.)
About 86% of Americans consume low-calorie, reduced-sugar, or sugar-free foods and beverages.2 Because of super-sized drinks and the widespread use of artificial sweeteners in food products, many people may be reaching or exceeding the acceptable daily intake of artificial sweeteners set by the FDA.2 For instance, a person weighing 150 lb (68 kg) can drink 30 to 32 cans of diet lemon-lime soda containing acesulfame potassium daily but only 6 cans of diet cola containing sucralose. For more details, see http://www.mayoclinic.com/health/artifical-sweeteners/my00073.
Many people believe that drinking diet soda will help them reduce body weight and lower the risk of obesity and diabetes, but the evidence is unclear. Some studies in humans indicate that sugar substitutes can help with short-term weight loss, yet an equal number suggest that they don't.2
In one study, research subjects who consumed more than one daily serving of diet soda had a 36% greater risk of metabolic syndrome: a cluster of risk factors (including hyperglycemia, hypertension, abdominal obesity, and hypertriglyceridemia) that significantly increases the risk of heart disease, stroke, and diabetes.3
This study also found that people who consume diet soda daily have a 67% higher risk of type 2 diabetes compared with those who didn't consume diet soda, possibly due to artificial sweeteners' effect on insulin resistance and glucose metabolism.3 Artificial sweeteners are 200 to 13,000 times as sweet as sugar, and this enhanced sweetness is mildly addictive.2 Sweet taste triggers the dopamine signal, the same pathway triggered by drugs of abuse such as cocaine.2 If artificially sweetened sodas increase cravings, a person may need more sweets to feel satisfied, leading to excessive calorie consumption and weight gain.4
The Framingham Osteoporosis Study found diet and regular cola drinks are associated with decreased bone mineral density in women but not in men.5 The caffeine and phosphorous in cola may interfere with normal calcium absorption, increasing the incidence of osteoporosis and the risk of fracture.
Diet soda is considered devoid of any nutritional benefit and may displace more nutritionally rich beverages in the diet, such as milk, which contains calcium, vitamin D, and protein, or water for hydration. Consuming diet drinks is associated with dental erosion because of their acidic pH level.6 Because aspartame is composed of two amino acids, aspartic acid and phenylalanine, it's not recommended for those with phenylketonuria.7
Assess your patient's dietary intake, paying special attention to their usual intake of diet or regular sodas and foods containing artificial sweeteners. Discuss the health risks of diet soda, then refer the patient to a registered dietitian or the primary healthcare provider for long-term support.
1. National Cancer Institute. Artificial sweeteners and cancer
2. Whitehouse CR, Boullata J, McCauley LA. The potential toxicity of artificial sweeteners. AAOHN J
3. Nettleton JA, Lutsey PL, Wang Y, Lima JA, Michos ED, Jacobs DR Jr. Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA). Diabetes Care
4. Swithers SE, Davidson TL. A role for sweet taste: calorie predictive relations in energy regulation by rats. Behav Neurosci
5. Tucker KL, Morita K, Qiao N, Hannan MT, Cupples LA, Kiel DP. Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis Study. Am J Clin Nutr
6. Lussi A, Jaeggi T. Erosion—diagnosis and risk factors. Clin Oral Investig
. 2008;12(suppl 1):S5-S13.
7. Mayo Clinic. Phenylketonuria. Treatments and drugs