What Are Nutritional Supplements?, Do They Work?



Nutritional Supplements


The definition of a nutritional supplement is broad—it covers any product added to the diet.

In most health and wellness references, the terms “nutritional supplements” and “dietary supplements” are interchangeable.

No matter which term you use, an important thing to remember about supplements is that, unlike medications, they are not controlled by the U.S. Food & Drug Administration. Therefore, they are not required to prove effectiveness before they are marketed.

However, the FDA monitors the information on the labels of nutritional supplements for accuracy and makes sure that the supplements’ labels do not make false claims about benefits.

The government can take action manufacturers of nutritional supplements if the companies claim that the products can treat or cure diseases or if there is evidence that any supplements are unsafe.

Nutritional supplements can refer to many products that many adults in the United States take daily or occasionally.

Some examples include vitamin C cough drops, multivitamin tablets, or calcium chews.

Nutritional supplements also include herbal products such as echinacea, which some people take to improve the immune system and avoid or treat colds, and specialized supplements such as glucosamine, which some people take to relieve joint pain.

The Institute of Medicine recommends that adults aged 50 years and older consume vitamin B-12 through fortified foods (many pieces of bread and cereals) or a multivitamin.

Nutritional supplements have labels listing the contents, including the amount of active ingredient (such as vitamin C) per serving and other ingredients such as fillers and flavors.

Although supplements can be helpful to people who aren’t getting enough of certain essential nutrients, they should not substitute for a healthy diet.


Scientific studies support the effectiveness of some supplements to manage certain conditions, such as taking calcium and vitamin D to help reduce bone loss.

Also, the Centers for Disease Control and Prevention advises women of reproductive age to take 400 mcg of folic acid per day to minimize the risk of congenital disabilities, as many pregnancies are unplanned.

However, many foods are already fortified with some of the popular nutritional supplements, such as vitamin A, iron, and calcium, and nutritional supplements are not necessary for most healthy people.

For those who do take supplements, more is not better, and too much of some nutrients can increase the risk of side effects ranging from headaches and nausea to liver damage. Follow the product label recommendations for dosing.

Individuals who could benefit from nutritional supplements include those who don’t eat well or do not eat enough for various reasons; those who follow vegan, vegetarian, or other restrictive diets that eliminate large categories of foods;

those who do not consume seafood, which provides omega-3 fatty acids important for heart health; those who have lactose intolerance or otherwise don’t consume enough dairy foods;

those who have medical conditions such as gastrointestinal disorders or allergies that prevent them from consuming and retaining enough nutrients,

those with heavy menstrual bleeding (which can cause excess loss of iron); and those who are unable to digest and absorb nutrients because of surgery.

Some supplements may cause side effects because of how they interact with prescription medications, or they may make prescription medications less effective.

For example, vitamin K supplements have been shown to make blood thinner medication less effective, so patients on blood diluting medications should not take these supplements without consulting a doctor.

Women who are expectant or nursing also should check with their doctors before taking nutritional supplements.

Although nutritional supplements have their place, it is important not to underestimate the value of whole foods.

Whole foods provide three key benefits that nutritional supplements do not:

  • Micronutrients. Whole foods are complex and contain micronutrients needed for good health that cannot be replicated in a supplement.
  • Fiber. Whole foods contain dietary fiber that can help improve digestion and nutrient absorption and reduce the risk for conditions including diabetes and heart disease.
  • Antioxidants. Whole foods boost the immune system with antioxidants in a way that antioxidant supplements have not been proven to do. The antioxidants in foods help slow a natural process in the body, leading to cell and tissue damage.



“Dietary Supplements: What You Need to Know.” National Institutes of Health Office of Dietary Supplements. June 17, 2011. https://ods.od.nih.gov/HealthInformation/DS_WhatYouNeedToKnow.aspx (accessed November 27, 2018).

“Supplements: Nutrition in a Pill?” Mayo Clinic. October 25, 2017. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/supplements/art-20044894 (accessed November 28, 2018).

“Vitamin B12.” National Institutes of Health Office of Dietary Supplements. November 29, 2018. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/ (accessed February 19, 2109).