Taking a multivitamin may be a good ‘insurance’ plan for those who are not a diet that includes a rainbow of fruits/veggies every day. If you do take a multi, check your bottle label to make sure that you are reaching optimal daily allowances (ODA) versus the bottom line required daily allowances (RDA) that most multi’s feature. If scurvy (the absolute deficiency disease related to vitamin C) was a problem in North America, perhaps taking 50mg of Vit-C in a multi might advantage. Otherwise, the reason you take hudreds of milligrams is to help with the vitality of your immune system, skin, and to protect you against cancer among other things.
If you discover that your multi is falling short, it may benefit you to take the “ACES” separately and together. Also, ensure that you are not consuming the cheap synthetic and possibly harmful forms of vitamins which may in fact do more harm than good!
Why “ACES” together? In order to neutralize free radicals (the reason you’re told to eat more blueberries and take your vitamins), antioxidants need to work like a team of firemen putting out a fire: some man the pumper truck, some are up the ladder, some are at the hose. Some move right in close to the fire to put out the flames, where others help the victims of smoke inhalation back away from the fire. You can’t get away with sending only one antioxidant – say Vitamin E – into the fray: that would be like having all the firemen rush to the end of the hose, with no one left to turn on the water. Using single antioxidants in high doses can actually do you more harm than good. There’s a synergy between these antioxidants that slows aging and prevents disease.
No one disputes the value of antioxidants in diet, especially where nature provides them in useful combinations. Recent studies have suggested that high doses of certain antioxidants (especially taken without considering for necessary synergy) may have marginally increased mortality in some studied groups.

Vitamin A (Beta-carotene)

Best Food Sources: Dark orange, red, yellow and green vegetables and fruits such as broccoli, kale, spinach, sweet potatoes, carrots, red and yellow peppers, apricots, cantaloupe and mangos.
Best Supplement Form: Beta Carotene (as part of a mixed carotenoid product).
ODA (optimal daily allowance): 15,000 IU daily for the average adult
Little known fact: Preformed vitamin A (identified on vitamin labels as “retinol” or “vitamin a palmitate”) can weaken bones.

Vitamin C

Best Food Sources: Berries, dark green vegetables (spinach, asparagus, green peppers, Brussels sprouts, broccoli, watercress, other greens), red and yellow peppers, tomatoes and tomato juice, mangos, papaya and guava.
Best Supplement Form: calcium ascorbate (slight advantage over ascorbic acid is that it is easier on the stomach)
ODA (optimal daily allowance): 250mg daily for the average adult
Little known fact: For most healthy individuals, the body can only hold and use about 250mg of vitamin C a day, but smokers, those taking oral contraceptives/estrogens, tetracyclines, and barbiturates, as well as those with personal diagnosis of mental illness including schizophrenia, all need far more vitamin-C

Vitamin E

Best Food Sources: Vegetable oils such as olive, soybean oil, nuts and nut butters, seeds, whole grains, wheat, wheat germ, brown rice, oatmeal, soybeans, sweet potatoes, legumes (beans, lentils, split peas) and dark green leafy vegetables.
Best Supplement Form: whole complex, including mixed tocopherols and mixed tocotrienols (avoid dl-alpha-tocopherol, which is the synthetic form.)
ODA (optimal daily allowance): 400 to 800 IU daily for the average adult
Little known fact: vit-E can dramatically reduce the benefits of cholesterol medication and can act as an anti-coagulant (thins the blood)

Selenium

Best Food Sources: Brazil nuts, brewer’s yeast, oatmeal, brown rice, chicken, eggs, dairy products, garlic, molasses, onions, salmon, seafood, tuna, wheat germ, whole grains, most vegetables.
Best Supplement Form: the organic form of selenium, such as yeast bound selenium or selenomethionine (avoid the inorganic form sodium selenite as vit-C interferes with its absorption)
ODA (optimal daily allowance): 200mcg (micrograms) daily for the average adult
Little known fact: Brazil nuts are such an abundant source of selenium – one nut provides about 200 mcg – that the NIH warns that Brazil nuts should be eaten “only occasionally” because of their unusually high selenium levels