Choosing a Multi-Vitamin

We hope to meet our nutritional needs by eating a well-balanced diet. During the period of diagnosis, treatment and recovery, your nutritional needs may change. It can be helpful to schedule an individual appointment with one of the cancer center dietitians to review your diet and assure that your nutritional needs are being met. To schedule a nutrition appointment, call your UCSF cancer center physician's office.

Who May Need a Multi-Vitamin Supplement

The following situations may make it difficult for you to meet your nutritional needs without adding vitamin and mineral supplements to your diet.

  • If you have had loss of appetite, taste, or smell, or have had surgery to the head and neck area resulting in difficulty with swallowing.
  • If you're female, postmenopausal, and not on hormone replacement therapy or tamoxifen, you may need to supplement with calcium, vitamin D, and/or vitamin K2 to protect against osteoporosis.
  • If you have cancer of the digestive tract, such as intestinal, pancreatic, liver, and gallbladder cancer, you may have impaired digestion and absorption of nutrients.
  • If you eat fewer than 1,200 calories per day or your diet is limited because of food intolerances.
  • If you follow a special diet that eliminates certain food groups, or if you eat a vegetarian diet that omits all animal products, you may need additional vitamin B12, calcium, and/or zinc.
  • If you have been told that you have poor wound healing due to nutrient deficiencies, additional vitamin C, zinc, and/or protein may be helpful.
  • If you are over age 50, your nutritional requirements for certain nutrients increase (such as vitamin B12 and vitamin D). Thus, you may need supplementation, particularly if you have loss of appetite and eliminate certain food groups.

How to Choose a Multi-Vitamin

If you decide that a multivitamin is for you, the number one thing to remember is to carefully read the label to make sure that the supplement is appropriate for you.

  • Check the Daily Value (DV). The DV is a government standard that specifies the minimum daily requirements that helps prevent a deficiency disease for healthy people. The DV is based on a caloric intake of at least 2,000 calories per day. In general, females have this caloric requirement or less per day, and males may have greater caloric needs.
  • Check the serving size. Look for how many tablets are needed to provide the stated nutrients. You may need to swallow up to six tablets a day to get the amounts listed on the label. A one or two per day multi may be preferred.
  • Skip the iron in a multivitamin. For cancer patients, it is advisable to ask your medical team about whether or not you should take iron in a multivitamin. Generally speaking, unless you have iron-deficient anemia, are at risk of anemia, or have had recent surgery, it is best to avoid extra iron because excess iron can have oxidative effects. Iron supplements can cause constipation and will require you to increase your fiber and fluid intake.
  • Opt for a multivitamin using methylated B vitamins. These will be better absorbed, particularly for those who have a genetic variant in any of the methylation related genetic single nucleotide polymorphisms (SNPs). Seek to find vitamin B12 in the form of methylcobalamin, adenosylcobalamin, and/or hydroxycobalamin. The most bioavailable form of vitamin B6 is pyridoxial-5-phosphate (P5P). And be sure to choose a folate that reads methylated folate, such as 5-methyltetrahydrofolate (5-MTHF).
  • Chelated or not? Chelated ("key-lated") minerals may be better absorbed by 5-10% because they are protected from substances in foods that can bind with it. For example, the phytic acid in grains or the oxalates in spinach can bind with minerals like calcium, lessening the absorption. Chelated minerals, however, may be more expensive than non-chelated minerals. Evaluate the price of the chelated mineral to determine if it is worth the additional cost. To improve absorption, take your supplement with food.
  • Read specialized formulas (i.e., those for women, men, seniors, etc.) carefully to see that they provide the recommended DVs. Since the dosage in each formula is not regulated, there is considerable variation among formulas. For example, most women's formulas have additional calcium but may lack the DV for vitamin D, which improves the absorption and utilization of calcium. Senior formulas may not contain the appropriate amount of DV for vitamin B12 or vitamin D.
  • Look for the expiration date!
  • Avoid megadoses. Megadoses of fat-soluble vitamins, such as vitamins, A, D, and E, and minerals should be used with caution as excess dosages can be stored in your liver, adding further demand to your liver. Additionally, there could be consequences with taking excessive dosages of some minerals, including selenium, copper, and zinc.
  • Avoid added agents like coloring (such as yellow #5), and additional fillers.
  • Look for 100% of the DV for Vitamins B1 (thiamin), B2 (riboflavin), niacin, Vitamins B6, B12, A, C, D, E and folic acid. Beta-carotene and vitamin A, both of which act as strong antioxidants, are in most multi-vitamin supplements. Beta-carotene is converted to vitamin A, but will not cause vitamin A toxicity.
  • If you do intend on using additional supplements of the antioxidants such as vitamin C or E, it may be advantageous to take these separately. Most of the multi-vitamins do not provide adequate amounts of the antioxidants. However, higher dosages of vitamin C (greater than 1000 mg) may act as prooxidants and promote oxidative damage. Additionally, high amounts of vitamin C may cause diarrhea, gas or stomach upset. It may be advisable to take smaller dosages more often. If you’re interested in taking high dose vitamin C, please consult with your healthcare practitioner on how to do so safely.
  • Look for minimal amounts of phosphorus. We easily get enough from our diets. Too much can prevent calcium absorption.
  • Look for "USP" on a label. This specifies that the supplement meets the standards of the U.S. Pharmacopoeia, meaning that they have undergone testing for dissolvability that mimics what happens in your body.

General Tips

  • Discuss any vitamins or supplements that you are taking with your medical team to ensure that there are no adverse interactions with your treatment. Many practitioners recommend stopping any high dose supplements during the time you are receiving chemotherapy or radiation therapy.
  • Take supplements with food unless specifically instructed otherwise. Doing so assists with absorption, since multivitamins, as a rule, work better when taken with food.
  • Supplements are available in liquid form or chewable form to ease any problems with swallowing. Determine what is the best form for you to take.
  • Treat nausea prior to taking a multivitamin. Remember to take the multivitamin with meals rather than on an empty stomach
  • Keep in mind that a multivitamin simply serves as additional assurance. It is not a substitute for eating well.

Special Considerations

Chemotherapy Agents

Use of certain chemotherapy medications may require additional supplementation. Be sure to ask your medical team before supplementing. Cisplatin use may require additional magnesium and potassium. Good food sources of magnesium include whole grains, nuts, legumes, dark green leafy vegetables and meat. Good dietary sources of potassium include strawberries, red peppers, bananas, oranges, potatoes, and apricots. Look for 100% of DV or more for magnesium. Usually, your multi-vitamin will not contain potassium. You may need additional supplementation in addition to the amount in your multivitamin. Your medical team will determine this based on your blood levels.

Chronic Illness

Chronic illness can lead to poor eating habits or deplete your nutrient stores. Extra-strength formulas may be important if you have a long-term digestive problem or have liver or gallbladder problems. Be sure to consult with your medical team on your individual needs before taking supplements.

Fast Foods or Processed Foods

These food groups contain an unusually high amount of sodium and possibly phosphorus. Be sure to look for lower amounts of phosphorous in your multi-vitamin. Too much phosphorus will interfere with calcium absorption.

Daily Values

Daily values reflect the recommended levels of intake for most vitamins and minerals and you will see these on a multivitamin label. If you take a multivitamin and other supplements, make sure to keep the combined levels within the safe tolerable upper intake levels.


Daily Values*

Tolerable Upper Levels**


1.5 mg



1.7 mg



20 mg

35 mg

Vitamin B6

2 mg

100 mg

Vitamin B12

6 mcg



0.3 mg


Pantothenic Acid

10 mg


Vitamin A

5,000 IU

10,000 IU, 3,000 mcg or RE

Vitamin C

60 mg

2,000 mg

Vitamin D

400 IU

2,000 IU or 50 mcg

Vitamin E

0 IU

1,000 mg; Discuss with physician if on anticoagulant therapy.


400 mcg

1,000 mcg or 1 mg


1,000 mg

2,500 mg


18 mg

45 mg


70 mcg

400 mcg


1,000 mg

4,000 mg


150 mcg

1,100 mcg


400 mg

350 mg (from nonfood sources)


15 mg

40 mg


2 mg

10 mg


2 mg

11 mg


120 mcg



75 mcg

2,000 mcg

* mg = milligrams; mcg = micrograms; IU = international units

** Tolerable upper intake levels listed are for adults (19+ years). If "None" is listed, no upper limit has been determined due to lack of data, not because these nutrients are safe to consume at any level of intake. All nutrients can have adverse effects when intakes are excessive.

For additional information or resources, please visit the Patient and Family Cancer Support Center (Mission Bay) at 1825 Fourth Street, First Floor or The Ida and Joseph Friend Patient and Family Cancer Support Center (Mount Zion) at 1600 Divisadero Street, B-101on the first floor, or call (415) 885-3693.

The information in this publication is designed for educational purposes only and is not intended to replace the advice of your physician or health care provider, as each patient's circumstances are individual. We encourage you to discuss with your physician any questions and concerns that you may have.

Ida & Joseph Friend Cancer Resource Center [Reprints Require Permission]