Minerals,
Vitamins and Supplements
Calcium.
Calcium recommendations for active men and pre-menopausal
women are not different than the RDA which is 800 mg for adults.
Studies from Heaney's laboratory report that calcium intake of
1500 mg/d is needed to retain calcium balance in women with low
circulating estrogens (28).
Thus higher calcium intakes may be required for amenorrheic as
well as postmenopausal athletes. Calcium intake, however, is one
of many factors associated with calcium balance, and accounts
for only ~11% of its variation .
(29)Urinary
calcium excretion, on the other hand, accounts for ~51% of the
variation in calcium balance and is influenced by dietary protein,
sodium and possibly phosphoric acid intakes. There is evidence
to suggest that vegans (and possibly vegetarians who consume little
dairy products) may have lower calcium requirements due to their
lower intakes of animal protein, total protein and sodium which
increase renal calcium excretion (7). However, until more is known
about calcium requirements in this group, it is prudent that all
athletes meet the RDA for calcium. Low calcium intake has been
associated with an increased risk of stress fractures (30)
and low bone density particularly in amenorrheic females athletes
.
(31)Eumenorrheic
athletes can meet calcium requirements by including several servings
of dairy products and/or calcium-containing plant foods daily.
Calcium-rich plant foods include kale, collard and mustard greens,
broccoli, bok choy, legumes, calcium-set tofu, fortified soymilk,
TVP, tahini, calcium-fortified orange juice, almonds, and blackstrap
molasses. Depending on their energy intake and food choices, female
vegan athletes may need to use fortified foods or calcium supplements
to meet their calcium requirements, particularly if amenorrhea
is evident. Well absorbed calcium supplements such as calcium
carbonate are appropriate when the athlete does not have access
to, or cannot afford calcium-fortified foods.
