chapter
chapter
9
11
Minerals
and
B Vitamins
Exercise
Important in
Energy Metabolism
Prof Jennifer Broxterman, RD, MSc
FN3373: Nutrition for Physical Activity
Lecture
9
Author name here for Edited books
Exercise-Related
Functions, Dietary
Requirements, &
Food Sources
Iron
• Primary functions:
– Transport oxygen in red blood cells
– Also important for energy metabolism during exercise
• Dietary sources:
– Heme: meat, fish, poultry (higher bioavailability)
– Non-heme: grains, legumes, vegetables, fruit
• RDA:
– 8 mg/day (men), 18 mg/day (premenopausal women)
Copper
• Primary functions:
– Required for proper iron metabolism & hemoglobin
production
– Also important for energy metabolism
• Cofactor for the enzymes of the electron transport pathway
• Required for superoxide dismutase (SOD)
– Synthesis and maintenance of collagen
• Dietary sources:
– Meat, seafood, vegetables, legumes, peanut butter,
nuts/seeds, wheat bran cereals, whole grain products
• RDA:
– 900 μg/day (men & women)
Zinc
• Primary functions:
– Required for the structure and function of more than
300 enzymes in the human body
– Superoxide dismutase is a zinc-dependent enzyme
– Required for nucleic acid and protein synthesis, cellular
differentiation & replication, and muscle function
– Exerts regulatory actions in the production, storage,
and secretion of various hormones
– Important in wound healing & skin integrity
– Also necessary for skeletal & brain development,
proper taste acuity, reproduction, and immune and
gastrointestinal function
Zinc
• Dietary sources:
– Shellfish, red meat (i.e. beef), nuts, legumes
• RDA:
– 11 mg/day (men), 8 mg/day (women)
– UL: 40 mg/day
• Zinc deficiency:
– Growth retardation, delayed wound healing,
impaired immune function, decreased taste acuity,
anorexia, and a variety of skin ailments and lesions
Magnesium
• Primary functions:
– Cofactor for over 300 enzymes
• Mg is needed by enzymes that catalyze reactions in cellular
energy production and storage, protein synthesis, DNA & RNA
synthesis, cell growth and reproduction, maintenance of
electrolyte balance, stabilization of mitochondrial membranes
– Required for the glycolytic pathway, the synthesis &
oxidation of fatty acids and proteins, ATP hydrolysis,
and the formation of cyclic adenosine monophosphate
(cAMP)
– Control of neuromuscular transmission, cardiac
excitability, vasomotor tone, and blood pressure
Magnesium
• Dietary sources:
– Green leafy vegetables, whole grains (germ & bran),
seeds, legumes
• RDA:
– Men: 400 mg/d (19-30 yo); 420 mg/d (31-70 yo)
– Women: 310 mg/d (19-30 yo), 320 mg/d (31-70 yo)
– UL for supplemental Mg = 350 mg/d
• Magnesium deficiency:
– Rare in healthy individuals
Chromium
• Primary functions:
– Potentiate the effect of insulin
– Constituent of glucose tolerance factor (GTF)
– Important for growth, synthesis of DNA & RNA, and
proper immune function
• Dietary sources:
– Processed meats, whole grains, wheat germ, readyto-eat bran cereals, green beans, broccoli,
mushrooms, spices, beer & wine
Chromium
• AI:
– 35 μg/day (men), 25 μg/day (women)
– UL not established
Table 11.1
Mineral Status in Athletes
& Rationale for Increased
Need for Active Individuals
Zinc Intake
• Most infants, children, and adults consume the
recommended amount of zinc (IOM, 2001)
• Females athletes are more likely to have
inadequate Zn intakes compared to males
– Usually attributed to their overall lower energy intake
and lower intakes of Zn-rich foods (i.e. protein-rich
animal products)
• Athletes participating in sports that emphasize
leanness generally have lower mean Zn
intakes than athletes in other sports
Zinc & Athletic Performance
• Acute & chronic exercise affects Zn metabolism
– Endurance vs. resistance training
– Urinary zinc losses
– Chronic exercise
• Health and performance consequences?
– Muscular fatigue
– Carbonic anhydrase
• Supplementation advice
Magnesium Intake
• Mg intakes average 78% of the RDA (for men)
and 65% (for women).
• Mg intakes in male athletes is high
• Mg intake is compromised in female athletes
with sub-clinical EDs
Magnesium & Athletic Performance
• Prolonged or intense exercise results in sig.
decrease to serum magnesium levels
–
–
–
–
–
Serum Mg concentrations in marathon runners
Urinary Mg concentrations
Sweat losses of Mg
Adipocytes
Transient shift of Mg into skeletal muscle tissue
• Supplementation advice
Chromium Intake
• Chromium intake data
– No reliable nutrient databases for chromium
– Chromium supplementation studies
Chromium & Athletic Performance
• Chromium research in athletes:
– Little research on chromium status in active
individuals
– Exercise increases chromium concentrations
– Urinary chromium losses
– “Natural” way to enhance LBM
• Supplementation advice
Sports Nutrition Case Study
due next class for 3373
• Next class, be prepared to hand in your hard
copy of the Group Sports Nutrition Case Study
& Meal Planning Assignment at the front when
you arrive to class
• Make sure it is stapled properly together
(if not, go downstairs to the Brescia Library and
use their stapler before handing your
assignment in)