5. Dietary Supplements and Cancer

What does dietary reference values (DRV) consist of?

• Average requirements (used for research)

• Population reference intakes (used for recommendations)

• Adequate intakes

How is average requirement intake defined?

Intake level meeting personal requirement of 50% of the population

Population reference intake

Intake level sufficient for almost entire population (~97.5%)

This is the value found under RI% on vitamin bottles

Adequate intake

Intake level assumed to meet the needs of virtually everyone in the population (derived if average requirement and population reference intake cannot be determined)

Tolerable upper intake level

= highest intake level at which no harmful overdosage effects are to be expected from long-term exposure, this is NOT ideal intake level

Vitamin B6

• Cofactor of >150 reactions

• Never damage

Why is there a strict tolerable upper intake for vit B6

• Can cause peripheral neuropathy

Three forms of vitamin B6

• There are three types that are present mostly in our diet

What are ABC and D

Link between beta carotene and lung cancer

It was found that there was a 60% increase in the risk of lung cancer in smokers who took beta carotene.

• This was against the hypothesis because vitamin A is an antioxidant

• Therefore supplements should not be used for cancer prevention as no beneficial effects have been found.

Folic acid vs. folate

Folate = natural (vegetables & fruits)

Folic acid = Synthetic version

Benefit of folic acid

When you want to get pregnant, it is beneficial to take 400 mg until you are 12 weeks pregnant

Effect of folic acid on cancer patients

• Folic acid can help with the efficiency of chemo therapy

• However, too much may also affect the healthy parts of your body if chemo works too well

Antioxidants and cancer

• Caused fewer toxicities

• However, if the antioxidants help repair, then they might also repair the cancerous cells

• Therefore, balance: you want antioxidants but not too many so that it prevents the effectiveness of the treatment.

Multivitamin use after cancer

• At 3-5 tablets per week, the mortality risk was lower

• However, more than 10 tablets increased the mortality risk