Minerals
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1. Do I need to supplement with magnesium during training?
No. For training or competition of less than half a day your solid food intake, and
therefore magnesium intake, may be low. However, the amount of magnesium losses in
perspiration is also low (0.5 mM, or ~15 mg / Qt or L). A small amount of
supplementation will ensure that you are kept at baseline levels, but focusing on
magnesium supplementation by itself has been shown to produce osmotic diarrhea and
dehydration.
2. Are there any minerals I need to be particularly careful about when
supplementing?
Yes. Zinc (>1 x RDA), manganese (>2 x RDA), chromium picolinate (>5 x RDA), and
selenium (>10 x RDA). These minerals, when taken over the Recommended Daily
Allowance (by the amounts shown in parenthesis), cause copper deficiency,
neurological damage, DNA / genetic damage, and reduced protein synthesis,
respectively. Chromium is generally safe but is not safe if taken in the form of
picolinate. Zinc and manganese are the only two minerals whose RDA is close to, or
even overlaps with, documented toxicity. I am unaware of any studies documenting
toxicity for any mineral or vitamin when they are ingested as part of regular food.
Toxicity comes from supplementation or food contamination. Zinc is in shellfish, meat, &
whole grains. Manganese is in whole grains, legumes, nuts, vegetables, & fruit.
Selenium is in whole grains, meat, fish, dairy. Chromium is in mushrooms, prunes,
asparagus, & whole grains. These lists only include foods with the highest amounts (in
ranked order). Whole grains really win here. When you have a choice between whole
grains (fibrous bread, pasta, and rice) and the bleached versions, the choice is clear. I
recommend against supplementing (possibly to toxic levels) just to make up for
nutrient-deprived food.
No. For training or competition of less than half a day your solid food intake, and
therefore magnesium intake, may be low. However, the amount of magnesium losses in
perspiration is also low (0.5 mM, or ~15 mg / Qt or L). A small amount of
supplementation will ensure that you are kept at baseline levels, but focusing on
magnesium supplementation by itself has been shown to produce osmotic diarrhea and
dehydration.
2. Are there any minerals I need to be particularly careful about when
supplementing?
Yes. Zinc (>1 x RDA), manganese (>2 x RDA), chromium picolinate (>5 x RDA), and
selenium (>10 x RDA). These minerals, when taken over the Recommended Daily
Allowance (by the amounts shown in parenthesis), cause copper deficiency,
neurological damage, DNA / genetic damage, and reduced protein synthesis,
respectively. Chromium is generally safe but is not safe if taken in the form of
picolinate. Zinc and manganese are the only two minerals whose RDA is close to, or
even overlaps with, documented toxicity. I am unaware of any studies documenting
toxicity for any mineral or vitamin when they are ingested as part of regular food.
Toxicity comes from supplementation or food contamination. Zinc is in shellfish, meat, &
whole grains. Manganese is in whole grains, legumes, nuts, vegetables, & fruit.
Selenium is in whole grains, meat, fish, dairy. Chromium is in mushrooms, prunes,
asparagus, & whole grains. These lists only include foods with the highest amounts (in
ranked order). Whole grains really win here. When you have a choice between whole
grains (fibrous bread, pasta, and rice) and the bleached versions, the choice is clear. I
recommend against supplementing (possibly to toxic levels) just to make up for
nutrient-deprived food.
© Clyde F. Wilson