Skip to main content Accessibility help
×
Home

How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review

  • Norman J. Temple (a1)

Abstract

Large numbers of randomised controlled trials (RCT) have been carried out in order to investigate diet–disease relationships. This article examines eight sets of studies and compares the findings with those from epidemiological studies (cohort studies in seven of the cases). The studies cover the role of dietary factors in blood pressure, body weight, cancer and heart disease. In some cases, the findings from the two types of study are consistent, whereas in other cases the findings appear to be in conflict. A critical evaluation of this evidence suggests factors that may account for conflicting findings. Very often RCT recruit subjects with a history of the disease under study (or at high risk of it) and have a follow-up of only a few weeks or months. Cohort studies, in contrast, typically recruit healthy subjects and have a follow-up of 5–15 years. Owing to these differences, findings from RCT are not necessarily more reliable than those from well-designed prospective cohort studies. We cannot assume that the results of RCT can be freely applied beyond the specific features of the studies.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review
      Available formats
      ×

Copyright

Corresponding author

* Corresponding author: N. J. Temple, fax +1 780 675 6186, email normant@athabascau.ca

References

Hide All
1. Jacobs, DR & Temple, NJ (2012) Methods in nutrition research. In Nutritional Health: Strategies for Disease Prevention, 3rd ed. pp. 127 [NJ Temple, T Wilson and DR Jacobs, editors]. New York, NY: Humana Press.
2. Maki, KC, Slavin, JL, Rains, TM, et al. (2014) Limitations of observational evidence: implications for evidence-based dietary recommendations. Adv Nutr 5, 715.
3. Blumberg, J, Heaney, RP, Huncharek, M, et al. (2010) Evidence-based criteria in the nutritional context. Nutr Rev 68, 478484.
4. Temple, NJ (2014) Nutrition research and human disease: a critical appraisal of mechanistic research, cohort studies, and randomized trials. J Nutr Health Sci 2, 101.
5. Appel, LJ, Moore, TJ, Obarzanek, E, et al. (1997) A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med 336, 11171124.
6. Forman, JP, Stampfer, MJ & Curhan, GC (2009) Diet and lifestyle risk factors associated with incident hypertension in women. JAMA 302, 401411.
7. He, FJ & MacGregor, GA (2002) Effect of modest salt reduction on blood pressure: a meta-analysis of randomized trials. Implications for public health. J Hum Hypertens 16, 761770.
8. He, FJ & MacGregor, GA (2009) A comprehensive review on salt and health and current experience of worldwide salt reduction programmes. J Hum Hypertens 23, 363384.
9. Mente, A, O’Donnell, MJ, Rangarajan, S, et al. (2014) Association of urinary sodium and potassium excretion with blood pressure. N Engl J Med 371, 601611.
10. Malik, VS, Pan, A, Willett, WC, et al. (2013) Sugar-sweetened beverages and weight gain in children and adults: a systematic review and meta-analysis. Am J Clin Nutr 98, 10841102.
11. Te Morenga, L, Mallard, S & Mann, J (2012) Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. BMJ 346, e7492.
12. Pol, K, Christensen, R, Bartels, EM, et al. (2013) Whole grain and body weight changes in apparently healthy adults: a systematic review and meta-analysis of randomized controlled studies. Am J Clin Nutr 98, 872884.
13. Koh-Banerjee, P, Franz, M, Sampson, L, et al. (2004) Changes in whole-grain, bran, and cereal fiber consumption in relation to 8-y weight gain among men. Am J Clin Nutr 80, 12371245.
14. Liu, S, Willett, WC, Manson, JE, et al. (2003) Relation between changes in intakes of dietary fiber and grain products and changes in weight and development of obesity among middle-aged women. Am J Clin Nutr 78, 920927.
15. Du, H, van der A, DL, Boshuizen, HC, et al. (2010) Dietary fiber and subsequent changes in body weight and waist circumference in European men and women. Am J Clin Nutr 91, 329336.
16. Guallar, E, Stranges, S, Mulrow, C, et al. (2013) Enough is enough: stop wasting money on vitamin and mineral supplements. Ann Intern Med 159, 850851.
17. Watkins, ML, Erickson, JD, Thun, MJ, et al. (2000) Multivitamin use and mortality in a large prospective study. Am J Epidemiol 152, 149162.
18. Neuhouser, ML, Wassertheil-Smoller, S, Thomson, C, et al. (2009) Multivitamin use and risk of cancer and cardiovascular disease in the Women’s Health Initiative cohorts. Arch Intern Med 169, 294304.
19. Pocobelli, G, Peters, U, Kristal, AR, et al. (2009) Use of supplements of multivitamins, vitamin C, and vitamin E in relation to mortality. Am J Epidemiol 170, 472483.
20. Mursu, J, Robien, K, Harnack, LJ, et al. (2011) Dietary supplements and mortality in older women: the Iowa Women’s Health Study. Arch Intern Med 171, 16251633.
21. Park, SY, Murphy, SP, Wilkens, LR, et al. (2011) Multivitamin use and the risk of mortality and cancer incidence: the multiethnic cohort study. Am J Epidemiol 173, 906914.
22. Lee, EH, Myung, SK, Jeon, YJ, et al. (2011) Effects of selenium supplements on cancer prevention: meta-analysis of randomized controlled trials. Nutr Cancer 63, 11851195.
23. Lippman, SM, Klein, EA, Goodman, PJ, et al. (2009) Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA 301, 3951.
24. Zhuo, H, Smith, AH & Steinmaus, C (2004) Selenium and lung cancer: a quantitative analysis of heterogeneity in the current epidemiological literature. Cancer Epidemiol Biomarkers Prev 13, 771778.
25. Etminan, M, FitzGerald, JM, Gleave, M, et al. (2005) Intake of selenium in the prevention of prostate cancer: a systematic review and meta-analysis. Cancer Causes Control 16, 11251131.
26. Asano, T & McLeod, RS (2002) Dietary fibre for the prevention of colorectal adenomas and carcinomas. The Cochrane Database of Systematic Reviews, CD003430.
27. Aune, D, Chan, DS, Lau, R, et al. (2011) Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies. BMJ 343, d6617.
28. Mozaffarian, D & Wu, JH (2011) Omega-3 fatty acids and cardiovascular disease: effects on risk factors, molecular pathways, and clinical events. J Am Coll Cardiol 58, 20472067.
29. Rizos, EC, Ntzani, EE, Bika, E, et al. (2012) Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA 308, 10241033.
30. Zheng, J, Huang, T, Yu, Y, et al. (2012) Fish consumption and CHD mortality: an updated meta-analysis of seventeen cohort studies. Public Health Nutr 15, 725737.
31. James, MJ, Sullivan, TR, Metcalf, RG, et al. (2014) Pitfalls in the use of randomised controlled trials for fish oil studies with cardiac patients. Br J Nutr 112, 812820.
32. Cook, NR, Cutler, JA, Obarzanek, E, et al. (2007) Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP). BMJ 334, 885888.
33. Zeng, R, Xu, CH, Xu, YN, et al. (2015) The effect of folate fortification on folic acid-based homocysteine-lowering intervention and stroke risk: a meta-analysis. Public Health Nutr 18, 15141521.
34. Parker-Pope, T (2011) The women’s health initiative and the body politic. New York Times, 9 April. http://www.nytimes.com/2011/04/10/weekinreview/10estrogen.html?pagewanted=all&_r=0 (accessed August 2013).
35. Ascherio, A, Rimm, EB, Stampfer, MJ, et al. (1995) Dietary intake of marine n-3 fatty acids, fish intake, and the risk of coronary disease among men. N Engl J Med 332, 977982.
36. Temple, NJ (2015) The possible importance of income and education as covariates in cohort studies. F1000Research 4, 690.
37. Jacobs, DR (2012) Challenges in research in nutritional epidemiology. In Nutritional Health: Strategies for Disease Prevention, 3rd ed. pp. 2942 [NJ Temple, T Wilson and DR Jacobs, editors]. New York, NY: Humana Press.
38. Stringhini, S, Sabia, S, Shipley, M, et al. (2010) Association of socioeconomic position with health behaviors and mortality. JAMA 303, 11591166.

Keywords

How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review

  • Norman J. Temple (a1)

Metrics

Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed