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Q:Is grass-fed beef
included in the recommended limit on red meat consumption?
A: Yes. The most recent recommendations based on a
research-grounded, peer-reviewed report on how diet can influence
cancer risk advise no more than 18 ounces per week of red meat.
That includes beef, pork, lamb and goat. Nutrient content of
grass-fed beef does differ in several ways from grain-fed beef:
It tends to be lower in saturated fat and slightly higher in
omega-3 fat and conjugated linoleic acid (CLA), the latter two
both considered healthy types of fat. Content of some vitamins
and minerals differ, and interesting discussion is underway about
possible environmental differences. The population studies that
form part of the basis for the recommended limit on meat consumption
don’t differentiate between people consuming grass- or grain-fed
beef, and it is likely that grain-fed beef is by far most represented.
However, the report only makes recommendations supported by biological
evidence of how a cancer link works. A switch from grain- to
grass-fed beef does not resolve concerns about red meat, such
as the high amount of heme iron found in red meat. Regardless
of your choice, for now it makes sense to keep all the red meat
you eat within the recommended 18-ounce per week limit. |
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Q: Can you explain how
to check the vitamin A content information on food and supplement
labels against recommended amounts, since they seem to be listed
in different units?
A: It can be confusing! When the current vitamin A
recommendations were released in 2001, we switched from a system
that referred to International Units (IU) to one that uses micrograms
of Retinol Activity Equivalents (RAEs). Vitamin A from animal
sources, such as milk, meat, and eggs, is well absorbed in the
body in the form of retinol. Beta-carotene, which comes from
plant sources, is another form of vitamin A. When vitamin A comes
from retinol, the current recommended amounts translate to 2330
IU for women and 3000 IU for men. Nutrition Labels also express
vitamin A as %DV (Percent of Daily Value), which tries to show
what proportion of the amount recommended in a healthy adult
diet is in one serving. But the DV for vitamin A is based on
the old, higher recommendations: 5000 IU. The 2001 recommendations
for vitamin A were lowered because research linked excess amounts
of retinol with bone weakening. So when it comes to vitamin A,
don’t aim for 100% DV. You will meet current recommendations
when foods and supplements add up to about 60% DV. Some food
and supplement labels do separate vitamin A into its sources:
retinol and beta-carotene. Although the studies linking bone
weakening relate to retinol, studies have found high levels of
beta-carotene from supplements – not food – also raise
health concerns for some populations.
Q: Is it true that coffee
blocks calcium absorption?
A: Caffeine-containing coffee does seem to slightly
decrease absorption of calcium, but the effect amounts to about
2 to 5 milligrams (mg) less calcium for each six-ounce cup of
coffee. The recommended amount of calcium for adults (ages 19
to 50) is 1,000 mg daily, so even multiple cups of coffee add
up to relatively small amounts. You may have heard of this effect
from past studies that linked coffee consumption to lower calcium
levels and weaker bone strength. These studies were few and relatively
short-term. More recent studies show past findings were often
more about coffee-drinkers getting less calcium, rather than
a sign of any biological effect of the coffee itself. |
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