Vitamins and Supplements 101: An expert breaks down the vitamins you actually need — and how to make them most effective

Shelley Weinstock, PhD, CNS earned her undergraduate degree from Bard College in Chemistry and her PhD from the Massachusetts Institute of Technology in Nutritional Biochemistry. She completed her postdoctoral research at the Harvard School of Public Health and then was on the Faculty at Barnard College at Columbia University. She is a Board-Certified Nutrition Specialist (CNS). She is currently in private practice and consults on research projects for academia, non-profits, and for-profit companies. Some of her clients include MIT and the Bill and Melinda Gates Foundation, Omeat, VitaKey, Glosslab, Kraft. She serves on scientific boards of companies, is a Fellow of the American College of Nutrition, and has numerous scientific papers and invited lectures.

“Take your vitamins!”

Even though that’s a saying many of us have heard before, the reason why taking those vitamins is important may not be as well-known.

Sure, you might know that vitamins and supplements can help support your diet and ensure you’re getting your daily essentials, but you may have questions about the specifics: Which vitamins are right for you? What high-quality ingredients do you look for? Are there any precautions to consider?

To cut through some of the misconceptions around vitamins and supplements, we partnered with Dr. Shelley Weinstock, PhD, a Board-Certified Nutrition Specialist, to create a Q&A for beginners looking to explore the world of vitamins and supplements.

Read below to learn more about what she shared:

On a basic level, what are vitamins and minerals and what are the differences between them? Vitamins and minerals are substances required by our bodies to carry out a myriad of normal cellular processes. They are not synthesized by our cells and must be consumed in foods and absorbed into our bodies via the gastrointestinal tract. Vitamins are organic molecules and are either fat soluble, and can be stored in our body fat, or water soluble, and unable to be stored with excess excreted in the urine. Some examples are Vitamins A, D, E, K (fat soluble) and B vitamins and vitamin C (water soluble). Minerals are inorganic elements such as calcium, magnesium, iron, zinc, sodium, iodine, and potassium. The government has established recommended dietary intakes (DRI’s) of vitamins and minerals.

What are some reasons people may need to take supplements? Adequate vitamin and mineral intake can be obtained by eating a healthy diet. However, many Americans do not adhere to the recommendations for a healthy diet as described by the USDA Dietary Guidelines for Americans. In addition to poor diet, there may be other reasons that some people need supplements, such as malabsorption issues, age, pregnancy, certain medical conditions. In general, a good multivitamin can be excellent insurance that one is meeting their requirements, especially in people over 50. As we age, several things affect consumption and absorption of nutrients. As an example, B12 absorption can go down with age. Those with dietary restrictions for any reason may need to supplement their diets. A person who is vegan may need B12 and omega 3’s. A prenatal vitamin will be prescribed during pregnancy. A person who survived a heart attack may be prescribed fish oil supplements. Someone on PPI’s (e.g.omeprazole) may need B12 and Calcium. Lastly, men’s and women’s needs may also differ. For example, premenopausal women need more iron than men.

What would you say are the top three most important vitamins people should be taking? For a generally healthy person who eats a good diet, the most important nutrients could be omega 3’s since they are anti-inflammatory and may support heart health, joints, and more. Folic acid and other B-vitamins are also important especially for women of childbearing age. Lastly, vitamin D, since many people are deficient in D and research shows its benefits.

Is there harm in taking a multivitamin every day?
If vitamin and mineral requirements are not met through diet, then a multivitamin can help to provide those nutrients. Multivitamins are generally regarded as safe although sometimes there can be gut related side effects that are often temporary. It’s a good idea to take a multivitamin with food to avoid potential side effects. It is important to know that the government does not regulate these the same way as they do drugs, so quality is very important. If a multivitamin has above the DRI recommendations, then it may not be safe.

Are there any supplements that warrant extra caution? Some vitamins are fat-soluble vitamins (A, D, E, K) and are stored in the body and can accumulate over time. Tolerable upper intake levels (UL) have been determined for vitamin and minerals and should be adhered to. For example, too much vitamin A for a pregnant woman could cause a birth defect.

Any specific food and drug interactions to look out for with common supplements? It’s always important to check with your doctor to determine if there are potential negative interactions with your medications and any supplements since there are many. For example, vitamin E can interfere with blood thinning medications and calcium can reduce the efficacy of some antibiotics.

Should you tell your healthcare provider what supplements you’re taking? You should absolutely let your doctor know what supplements you are taking. A Registered Dietitian (RD) or Certified Nutrition Specialist (CNS) can help you to determine which supplements are best for you.

What should people look for in a supplement in regard to ingredients and quality? It is important to know that the government has standards for dietary supplements but does not regulate them the same way they monitor drugs. Therefore, the quality of products can vary. Look for third party certified products, which should be indicated on the label, to be sure that you are ingesting the ingredients and amounts indicated on the label.

Could you expand on the importance of GMP-certified and third party tested supplements? GMP or Good Manufacturing Practice is a system for ensuring that products are consistently produced and controlled according to quality standards. Third party certification means that products are tested for harmful levels of contaminants and that they contain the ingredients listed on the label and nothing else.

Do you have any tips on use and storage? Do vitamins have a shelf life? Generally, vitamins have about a two-year shelf life after production. They are not harmful to take after that but decrease in strength, so they may not be as effective. All supplements should be stored away from heat, light, and moisture, and some supplements, such as probiotics, may need refrigeration.

Ready to say hello to a healthier you? Our line of vitamins and supplements are made with high-quality ingredients and are all GMP-certified (that means we consistently adhere to quality standards), so you never have to miss a day of feeling healthy and proactive. Fuel a healthier you each day with Vitamin D3, Omega-3 Fish Oil, Vitamin B6, and Vitamin B12, and browse options for pregnancy-related vitamins.


1. Vitamins and Minerals. Harvard School of Public Health: The Nutrition Source.URL . Accessed June 29, 2022.

2. NIH, Office of Dietary Supplements. URL. Accessed June 29, 2022.

3. Dietary Guidelines for Americans. URL. Accessed June 29, 2022.

4. Multivitamin/mineral Supplements Facet Sheet for Health Professionals. NIH. URL. Accessed June 29, 2022.

5. Nutrient recommendations, Dietary Recommended Intakes (DRI’s). NIH. URL. Accessed June 29, 2022.

6. Mixing medications and dietary supplements can endanger your health. U.S Food and Drug Administration.URL. Accessed June 29, 2022.

7. Current GMP practices for dietary supplements. U.S Food and Drug Administration. URL. Accessed June 29, 2022.

8. Questions and answers on dietary supplements. U.S Food and Drug Administration. URL. Accessed June 29, 2022.

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