6 controversial foods—and what to know about them
Is a gluten-free diet really healthier for? Can processed meat contribute to cancer?
Jan, 2026
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If you follow nutrition news, it seems like there’s a new food trend blaring across headlines each week. To add to the confusion, sometimes the same superfood lands on the must-eat and must-avoid lists at the same time. You’d be forgiven for questioning the foods and ingredients in your own pantry and fridge.
Does soy really increase breast cancer risk? Is going gluten-free worth doing if you don’t have celiac disease? Can coconut oil help you lose weight—or is it loaded with calories and unhealthy fats? Here are six of the most debated foods and what the research says about them.
Written byOlivia DeLong.
Medically reviewed byMegan Burke, MD.
Sources: Stacy Simon. Soy and Cancer Risk: Our Expert’s Advice. American Cancer Society. April 29 + 13
- Stacy Simon. Soy and Cancer Risk: Our Expert’s Advice. American Cancer Society. April 29, 2019.
- Wei Y, Lv J, Guo Y, et al. Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose-response meta-analysis. Eur J Epidemiol. 2020 Jun;35(6):567-578.
- Fan Y, Wang M, Li Z, et al. Intake of Soy, Soy Isoflavones and Soy Protein and Risk of Cancer Incidence and Mortality. Front Nutr. 2022 Mar 4;9:847421.
- Harvard T.H. Chan School of Public Health. Straight Talk about Soy. Accessed May 27, 2022.
- Diez-Sampedro A, Olenick M, Maltseva T, Flowers M. A Gluten-Free Diet, Not an Appropriate Choice without a Medical Diagnosis. J Nutr Metab. 2019;2019:2438934. Published 2019 Jul 1.
- World Health Organization. Cancer: Carcinogenicity of the consumption of red meat and processed meat. 2015.
- American Institute for Cancer Research. Limit Consumption of Red and Processed Meat. Accessed June 9, 2022.
- Holly Strawbridge. Artificial sweeteners: sugar-free, but at what cost? Harvard Health Publishing. January 29, 2020.
- Debras C, Chazelas E, Srour B, et al. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study. PLoS Med. 2022 Mar 24;19(3):e1003950.
- Singh N, Singh Lubana S, Arora S, Sachmechi I. A Study of Artificial Sweeteners and Thyroid Cancer Risk. J Clin Med Res. 2020 Aug;12(8):492-498.
- U.S. Food and Drug Administration. Questions and Answers on Monosodium glutamate (MSG). Content current as of: January 4, 2018.
- Harvard T.H. Chan School of Public Health. Coconut Oil. Accessed June 9, 2022.
- American Heart Association. Advisory: Replacing saturated fat with healthier fat could lower cardiovascular risks. Published: June 15, 2017.
- American Dental Association. Mouth Healthy. Oil pulling. 2018.
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