As a pharmacist, I often receive questions about supplements, supplement safety and effectiveness. Supplements are products taken by mouth that contain one or more dietary ingredients. They’re meant to supplement the diet — not replace it — and are labeled as dietary supplements. Examples include vitamins, minerals, herbals or botanicals, amino acids and probiotics.
In this article, I’ll discuss the 10 most common supplements I’m asked about, including their purpose and some practical advice. Let’s get started!
Vitamin B-12
Functions:
- Supports central nervous system development and function
- Assists in healthy red blood cell formation
- Functions as a cofactor for two enzymes required in DNA synthesis
Recommendations:
- Adults: 2.4 mcg/day
Commonly available: Cyanocobalamin
Important note: Vitamin B-12 is water soluble and the body will eliminate any amount not absorbed.
Vitamin D (calciferol)
Functions:
- Helps the body absorb calcium
- Supports muscle movement
- Helps nerves carry messages
- Aids immunity
Recommendations:
- Adults 19-70: 15 mcg or 600 IU/day
- Adults 71+: 20 mcg or 800 IU/day
Commonly available:
- D-2 Ergocalciferol
- D-3 Cholecalciferol
Important note: Vitamin D is fat soluble and the body will store it. Excess supplementation can lead to toxicity.
Multivitamin with minerals
Functions: Contain vitamins and minerals that each have a unique role in the body
Recommendations:
- Adults 19-50: Adult men or women formula
- Adults 50+: Senior men or women formula
- Pregnant/lactating women: Prenatal formula
Important note: Multivitamins cannot replace a healthy diet, which is the best source of vitamins and minerals.
Calcium
Functions:
- Builds and maintains strong bones and teeth
- Supports muscle movement
- Helps nerves carry messages
- Helps blood vessels move blood
- Assists with the release of hormones
Recommendations:
- Follow the serving instructions as provided on the package label.
- It is best to split the total daily dose into two separate doses per day.
Commonly available:
- Calcium carbonate: Take with food to increase absorption.
- Calcium citrate: Offers better absorption and can be taken with or without food
Magnesium
Functions:
- Required for the synthesis of DNA and RNA and the structural development of bone
- Cofactor in:
- Protein synthesis
- Muscle function
- Nerve function
- Blood glucose control
- Blood pressure regulation
Recommendations:
- Adults: 310-420 mg/day
Commonly available:
- Magnesium citrate: Laxative, digestive support
- Magnesium glycinate: Calming effect, anxiety reduction, promotes sleep
- Magnesium malate: Muscle support, energy enhancement
- Magnesium oxide: Indigestion and constipation relief
Important note: Each salt form has distinct characteristics in terms of solubility and bioavailability, resulting in varying health benefits.
Fish oil
Functions:
Forms signaling molecules that support:
- Cardiovascular health
- Pulmonary function
- Immune system
- Endocrine system
Recommendations:
- Adults: 1,000 mg/day
Commonly available:
- Fish oil
- Krill oil
- Cod liver oil
Omega-3 fatty acids
Functions:
- Provide energy for the body
- Form signaling molecules that support:
- Cardiovascular health
- Pulmonary function
- Immune system
- Endocrine system
- Important for cell membrane structure
Recommendations:
- Adults 19+: 1.1-1.6 grams/day
Important note: Omega-3 fatty acids research primarily focuses on three forms.
- Alpha-linolenic acid (ALA)
- Eicosapentaenoic acid (EPA)
- Docosahexaenoic acid (DHA)
Probiotics
Functions:
- Protect against pathogens
- Aid immune system development
- Aid and improve digestion
- Support energy production
Recommendations: Follow serving as provided on the package label.
Commonly available:
- Align
- Culturelle
- Florastor
- Garden of Life
- VSL#3
Joint supplement: Glucosamine and Chondroitin
Functions: May increase the cartilage and fluid around joints and prevent their breakdown
Recommendations: Follow the serving instructions as provided on the package label.
Commonly available:
- Cosamin
- Osteo Bi-Flex
- Move Free
Fiber supplement: Psyllium
Functions:
- Psyllium seed husk absorbs water in the stomach
- Forms a gel-like mass that can:
- Stimulate the bowel in patients with constipation
- Slow down the bowel in patients with diarrhea
Recommendations:
- Take at least 8 ounces of water with every dose:
- 3-5 grams of husk
- 7 grams of seed
- Limit use to 20 weeks or less.
Risks:
- Can lead to choking or blockage in the gastrointestinal tract if not taken with 8 ounces of water
- Long-term use may affect nutrient absorption.
Dietary supplements: Best practices
- Consult your medical provider for advice before starting any new supplements.
- Consult your pharmacist to avoid potential interactions with your current medications and determine the best dosing regimen.
- Choose brands that undergo independent third-party lab testing, verifying ingredient content and freedom from harmful contaminants.
- Choose products that are in date and have been stored properly.
- Keep a journal to document any side effects or concerns to discuss with your health care provider.
- Take all prescription and supplement bottles to each office visit.
Need help finding a provider? Click on Find a Doctor above to find one near you.
References:
- National Institutes of Health Office of Dietary Supplements – Dietary Supplements: ods.od.nih.gov/factsheets/DietarySupplements-Consumer
- NIH – Vitamin B12: ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional
- NIH – Vitamin D: ods.od.nih.gov/factsheets/VitaminD-HealthProfessional
- NIH – Multivitamin/Mineral Supplements: ods.od.nih.gov/factsheets/MVMS-HealthProfessional
- NIH – Calcium: ods.od.nih.gov/factsheets/Calcium-HealthProfessional
- NIH – Magnesium: ods.od.nih.gov/factsheets/Magnesium-HealthProfessional
- NIH – Omega-3 Fatty Acids: ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional
- NIH – Probiotics: ods.od.nih.gov/factsheets/Probiotics-HealthProfessional
- National Institute of Environmental Health Sciences – Microbiome: niehs.nih.gov/health/topics/science/microbiome
- MedlinePlus – Probiotics: medlineplus.gov/druginfo/natural/807.html
- MedlinePlus – Fish Oil: medlineplus.gov/druginfo/natural/744.html
- MedlinePlus – Magnesium: medlineplus.gov/druginfo/natural/866.html
