The Truth About Over-the-Counter Supplements: Do They Really Work?

Image Citation: [1]

Written by Max Mislow ‘28

Edited by Parsa Lajmiri ‘26

Every year, Americans spend over $60 billion on dietary supplements [2]. From fat-burning pills to "debloating" drinks, the supplement industry thrives on promising quick fixes. However, many of these products fail to deliver the results they claim and often lack substantial scientific backing. In this article, we’ll break down some of the most popular yet ineffective supplements and examine the research (or lack thereof) behind their claims.

Fat Burners: Do They Actually “Burn Fat”?

Fat burners promise to speed up metabolism and help users shed weight effortlessly. However, most rely on ingredients that have minimal fat-burning effects in real-world conditions. Caffeine and green tea extract are two common ingredients in fat burners. Caffeine works by stimulating the central nervous system, increasing adrenaline levels, and promoting a temporary rise in metabolic rate [3]. However, this effect is mild, short-lived, and diminishes with regular use as the body adapts. Green tea extract contains catechins, which have been shown to aid in fat oxidation, but the overall fat-loss effect is too minimal without a calorie deficit and exercise [4]. L-Carnitine is often marketed as a "fat oxidizer" because it helps transport fatty acids into mitochondria, where they can be used for energy [5]. However, studies have shown that in individuals who are not carnitine deficient, supplementation does not lead to increased fat burning or weight loss [6]. The body naturally regulates carnitine levels, and adding more through supplementation does not enhance fat metabolism in a meaningful way. Capsaicin, the compound found in chili peppers, has been studied for its thermogenic effects, as it can slightly raise body temperature and energy expenditure. However, the increase in calorie burn is minimal, and consuming capsaicin in supplement form does not produce the dramatic weight loss results often claimed by manufacturers [7]. Fat burners won’t replace a calorie deficit and exercise. At best, they provide a mild metabolic boost that won’t significantly impact fat loss, and should never replace a balanced diet paired with consistent exercise.

Vitamin Supplements: Are They Necessary?

Many people take multivitamins and individual vitamins believing they will improve overall health. However, studies suggest these supplements provide little benefit unless there is a pre-existing deficiency. Multivitamins are commonly used to "fill in the gaps" of a diet, but research has shown that for individuals who already consume sufficient nutrients, they do not lower the risk of chronic diseases or improve overall health outcomes [8]. The body tightly regulates nutrient absorption, so excess intake is often excreted without providing additional benefits [9]. Vitamin C is often taken to boost immunity, with the belief that it prevents colds. However, research has shown that while vitamin C may slightly reduce the duration of cold symptoms, it does not prevent illness in most people [10]. The body excretes excess vitamin C, making high doses unnecessary for general health [10]. Vitamin D plays a critical role in calcium absorption and bone health. While supplementation is necessary for individuals with low sun exposure or diagnosed deficiencies, excessive intake can lead to toxicity, causing hypercalcemia (excess calcium in the blood) and other complications [11]. B Vitamins are commonly marketed as energy boosters, but in reality, they do not directly increase energy levels unless a deficiency exists. B vitamins are essential for converting food into energy, but consuming extra beyond what the body needs does not provide additional energy [9]. Ultimately, if your diet is well-balanced, vitamin supplements likely provide little to no additional benefit.

Testosterone Boosters: Do They Actually Increase Testosterone?

Natural testosterone boosters are popular among men looking to enhance muscle growth, energy, and fat loss. However, most of these supplements lack strong scientific backing. Tribulus terrestris is frequently included in testosterone boosters due to claims that it enhances testosterone levels and libido. While some animal studies have shown potential benefits, human studies consistently fail to demonstrate a significant increase in testosterone levels in healthy men [12]. The compound may have minor effects on libido but does not appear to impact muscle growth or strength [13]. Fenugreek contains compounds that may inhibit enzymes responsible for converting testosterone into estrogen. Some small studies suggest it may modestly impact libido and free testosterone levels, but the overall effects on muscle mass and strength remain inconclusive [14]. D-Aspartic Acid gained attention after early studies suggested it could increase luteinizing hormone (LH), which signals the testes to produce testosterone. However, larger and more rigorous studies have failed to confirm these findings, showing no consistent or meaningful increase in testosterone levels [15]. ZMA (Zinc, Magnesium, and Vitamin B6) is often marketed as a natural testosterone booster, particularly for athletes. However, unless an individual is deficient in zinc or magnesium, supplementation does not result in increased testosterone production [16]. In those with normal nutrient levels, taking ZMA provides no hormonal benefits [16]. Most testosterone boosters fail to raise testosterone levels significantly. Unless you have a nutrient deficiency, these supplements are unlikely to help.

Image Citation: [17]

The Problem With Supplement Claims: No FDA Approval and Lack of Testing

Unlike prescription medications, dietary supplements are not subject to FDA approval before hitting the market. This means manufacturers can make bold claims without proving their products are effective. To take this issue even further, many over-the counter supplements contain some amount of unapproved and unregulated pharmaceutical ingredients [18]. Third-party testing through organizations like the NSF and USP can help verify ingredient purity and label accuracy, but even then, effectiveness is another issue entirely [2]. The best thing to do is to be mindful about what supplements you put in your body and only purchase them from a reputable supplement manufacturer with an NSF or USP seal on the bottle.

Final Thoughts:

The supplement industry is filled with bold claims, but scientific evidence often tells a different story. While some supplements can be beneficial in specific cases (e.g., vitamin D for those with low sun exposure or zinc for those deficient), many do not live up to their marketing hype. If you're looking for real results, focus on a solid diet, consistent training, and adequate recovery instead of relying on expensive, mostly ineffective pills that promise magical results.

References

1. Bluth R. Hidden Drugs And Danger Lurk In Over-The-Counter Supplements, Study Finds [Internet]. California Healthline. 2018 [cited 2025 Mar 3]. Available from: https://californiahealthline.org/news/hidden-drugs-and-danger-lurk-in-over-the-counter-supplements-study-finds/

2. Office of Dietary Supplements - ODS Director’s Message - April [Internet]. [cited 2025 Mar 3]. Available from: https://ods.od.nih.gov/About/DirectorsMessageApr2024.aspx

3. Nehlig A, Daval JL, Debry G. Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Res Brain Res Rev. 1992;17(2):139–70.

4. Gholami F, Antonio J, Iranpour M, Curtis J, Pereira F. Does green tea catechin enhance weight-loss effect of exercise training in overweight and obese individuals? a systematic review and meta-analysis of randomized trials. J Int Soc Sports Nutr. 21(1):2411029.

5. Healthline [Internet]. 2023 [cited 2025 Mar 3]. L-Carnitine: Benefits, Side Effects, Sources, and Dosage. Available from: https://www.healthline.com/nutrition/l-carnitine

6. Virmani MA, Cirulli M. The Role of l-Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation. Int J Mol Sci. 2022 Feb 28;23(5):2717.

7. Szallasi A. Capsaicin for Weight Control: “Exercise in a Pill” (or Just Another Fad)? Pharmaceuticals (Basel). 2022 Jul 11;15(7):851.

8. Ward E. Addressing nutritional gaps with multivitamin and mineral supplements. Nutr J. 2014 Jul 15;13:72.

9. Is There Really Any Benefit to Multivitamins? [Internet]. 2024 [cited 2025 Mar 3]. Available from: https://www.hopkinsmedicine.org/health/wellness-and-prevention/is-there-really-any-benefit-to-multivitamins

10. Chambial S, Dwivedi S, Shukla KK, John PJ, Sharma P. Vitamin C in Disease Prevention and Cure: An Overview. Indian J Clin Biochem. 2013 Oct;28(4):314–28.

11. Mayo Clinic [Internet]. [cited 2025 Mar 3]. Vitamin D. Available from: https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-20363792

12. Fernández-Lázaro D, Mielgo-Ayuso J, del Valle Soto M, Adams DP, González-Bernal JJ, Seco-Calvo J. The Effects of 6 Weeks of Tribulus terrestris L. Supplementation on Body Composition, Hormonal Response, Perceived Exertion, and CrossFit® Performance: A Randomized, Single-Blind, Placebo-Controlled Study. Nutrients. 2021 Nov 7;13(11):3969.

13. Clemesha CG, Thaker H, Samplaski MK. ‘Testosterone Boosting’ Supplements Composition and Claims Are not Supported by the Academic Literature. World J Mens Health. 2020 Jan;38(1):115–22.

14. Wankhede S, Mohan V, Thakurdesai P. Beneficial effects of fenugreek glycoside supplementation in male subjects during resistance training: A randomized controlled pilot study. J Sport Health Sci. 2016 Jun;5(2):176–82.

15. Roshanzamir F, Safavi SM. The putative effects of D-Aspartic acid on blood testosterone levels: A systematic review. Int J Reprod Biomed. 2017 Jan;15(1):1–10.

16. Wilborn CD, Kerksick CM, Campbell BI, Taylor LW, Marcello BM, Rasmussen CJ, et al. Effects of Zinc Magnesium Aspartate (ZMA) Supplementation on Training Adaptations and Markers of Anabolism and Catabolism. J Int Soc Sports Nutr. 2004 Dec 31;1(2):12–20.

17. Ensuring Compliance with FDA Regulations for Dietary Supplements [Internet]. 2023 [cited 2025 Mar 3]. Available from: http://www.rlfoodtestinglaboratory.com/ensuring-compliance-with-fda-regulations-for-dietary-supplements

18. Tucker J, Fischer T, Upjohn L, Mazzera D, Kumar M. Unapproved Pharmaceutical Ingredients Included in Dietary Supplements Associated With US Food and Drug Administration Warnings. JAMA Network Open. 2018 Oct 12;1(6):e183337.