Vitamin A
How much to get daily: 700 mcg (2,333 IU) / Don’t exceed (daily): 3,000 mcg (10,000 IU)
Why you need it: Vitamin A refers to several compounds, including retinol, retinal and retinoic acid. Along with provitamins such as beta carotene, it’s important for vision, bone growth, reproduction and cell differentiation. It also helps regulate the immune system.

What you need to know: Excess amounts of vitamin A accumulate and can be toxic. Too much can blur vision, cause headaches and vomiting, and also lead to liver, bone and central nervous system problems. Excess retinol can cause birth defects, so multivitamins should contain beta-carotene instead.

Vitamin E
How much to get daily: 15 mg (33 IU) / Don’t exceed (daily): 1,000 mg (2,222 IU)
Why you need it: It’s a powerful antioxidant that protects cells from damage and may guard against chronic disease. Vitamin E also supports immune function, DNA repair and other metabolic processes.

What you need to know: Large doses of vitamin E can thin the blood and may increase stroke risk in people with uncontrolled high blood pressure. It hasn’t actually been proven to protect the heart or prevent cancer. In fact, a recent study linked vitamin E supplements with an increased risk of lung cancer, especially among smokers.

Vitamin C
How much to get daily: 75 mg / Don’t exceed (daily): 2,000 mg
Why you need it: This antioxidant vitamin helps the body form collagen in bones, cartilage, muscle and blood vessels, and assists in the absorption of iron.

What you need to know: There is no conclusive evidence that vitamin C supplementation prevents colds, heart disease, cataracts or cancer. Very high doses may lead to gastrointestinal problems.

Vitamin D
How much to get daily: 5 mcg (200 IU) / Don’t exceed (daily): 50 mcg (2,000 IU)
Why you need it: It keeps your bones and teeth healthy by maintaining blood levels of calcium and phosphorus. Vitamin D may help protect against breast, prostate and colon cancers, and decrease the risk of osteoporosis, when combined with a healthy diet and regular exercise.

What you need to know: The Canadian Cancer Society recommends taking 25 mcg for fair-skinned people during the fall and winter and for dark-skinned people all year-round. Exceeding 50 mcg may cause vitamin D toxicity, leading to nausea, vomiting, constipation, weight loss and other symptoms.

How much to get daily: 1,000 mg / Don’t exceed (daily): 2,500 mg
Why you need it: This mineral helps maintain healthy bones and teeth.
Where to get it: Drink dairy or calcium-fortified beverages. Other food sources: vegetables, canned salmon and sardines, lentils and legumes.

What you need to know:Very high doses of calcium can lead to kidney problems, and can also interfere with the absorption of other essential minerals.

How much to get daily: 18 mg / Don’t exceed (daily): 45 mg
Why you need it: Iron is a component of many proteins and enzymes that maintain good health, including hemoglobin, which transports oxygen in the bloodstream.

What you need to know: Only women who are pregnant or have heavy periods, or vegetarians and those with diagnosed deficiencies, such as anemia, need extra amounts of iron. Supplements can interact with medications, other dietary supplements and food, and can worsen conditions like ulcers.

How much to get daily: 320 mg / Don’t exceed (daily): 350 mg
Why you need it: Essential to metabolism, this mineral also helps to maintain normal muscle and nerve function, to support healthy cardiovascular and immune systems, and to keep bones strong.

What you need to know: Too much magnesium from supplements may cause diarrhea, nausea and abdominal cramps.

Vitamin B6
How much to get daily: 1.3 mg / Don’t exceed (daily): 100 mg
Why you need it: This vitamin is involved in the synthesis of brain chemicals and red blood cells, metabolism and maintenance of blood-sugar levels.
Where to get it: Commonly found in fortified cereals, legumes, meat, poultry, fish and some fruits and vegetables.

What you need to know: Too much B6 can cause nerve damage.

Vitamin B12
How much to get daily: 2.4 mcg / Don’t exceed (daily): No upper limit established
Why you need it: B12 helps maintain healthy nerve cells and red blood cells. It’s also needed to help make DNA.