Vitamin/Supplement

Function/Intended Benefit

Safety Considerations

Vitamin A

Night vision, cell growth and maintenance, the health of the skin

Toxicity can occur if levels are too high, leading to headaches, peeling skin, and bone thickening.

Vitamin D

Calcium absorption, bone and tooth health, heart and nerve function

Toxicity can occur if levels are too high, leading to kidney failure, metastatic calcification, and anorexia.

Vitamin E

Protection of cells (including skin and brain), formation of blood cells

N/A

Vitamin K

Blood clotting, bone growth

Can counteract blood clotting medications, reducing their efficiency

Vitamin B1

Carbohydrate metabolism, heart, nerve, and muscle function

N/A

Vitamin B2

Fat and protein metabolism

N/A

Vitamin B3

Carbohydrate and fat metabolism

Toxicity can occur if levels are too high, leading to red, itching skin with tingling.

Vitamin B6

Enzyme assistance in the amino acid synthesis

Toxicity can occur if levels are too high, leading to peripheral neuropathy.

Vitamin B12

Protein and fat metabolism, nerve-cell maintenance, cell development

N/A

Vitamin C

Immunity, iron absorption, the structure of bones, muscle, and blood vessels

N/A

St. John’s wort

Treatment for depression, anxiety, and sleep disorders

Some studies found it ineffective in its intended benefits (similar results to a placebo).

No long-term safety studies have been conducted.

Black cohosh

Relief of menopause symptoms, including hot flashes, night sweats, headaches, heart palpitations, and mood changes

Large doses can cause vomiting, dizziness, and headaches.

Long-term studies have yet to be conducted (recommended to take for less than 6 months).

Melatonin

Melatonin is a naturally occurring hormone in the brain. Also can be taken as a supplement to potentially help with sleep regulation and combat aging (studies validate the support of sleep regulation but do not support anti-aging benefits).

Can result in drowsiness and headaches

May interfere with conception

Willow bark

Pain relief (one of the main ingredients of aspirin comes from willow bark)

Do not exceed 240 mg/day

Not safe for those who cannot tolerate aspirin

Glucosamine sulfate

Promote healthy cartilage formation to maintain or replace wear and tear on joints

No safety concerns

Recent studies found glucosamine sulfate to be no more effective than a placebo in knee osteoarthritis.

Gingko biloba

Improve memory and mental function by increasing blood flow to the brain

Extremely high doses can lead to nausea, vomiting, and diarrhea.