Q: Does the phytochemical content vary among different types of onions?
A: Phytochemicals are natural compounds found in plants that may
offer protection from a variety of diseases, including cancer. Onions are major
contributors to our consumption of the largest group of phytochemicals –
flavonoids – that act as powerful antioxidants. Phytochemical content of plant
foods always varies somewhat with growing conditions, but yellow and red onions
tend to contain much higher levels of flavonoids such as quercetin, when
compared to white onions, Vidalias and other sweet onions. Like garlic and
shallots, onions contain sulfur-containing phytochemicals that seem to provide
protection at several steps during the process of cancer development.
Researchers have not documented any
differences in content of these sulfur compounds among different types of
onions at this time.
You are best
advised to choose your onions based on their intended use, rather than their
phytochemical make-up. Yellow onions, by far the most common type, are
full-flavored and great for cooking – especially when recipes require longer
cooking times or when you want more flavor.
Many chefs consider red onions best for use raw in salads or sandwiches,
or for quick cooking recipes, like kabobs.
White onions have a sweet flavor and are the classic choice for
traditional Mexican cuisine.
Q: How much selenium do we need, and what foods supply it?
A: Selenium is a mineral and one of many antioxidants in our food
supply that may help lower risk of cancer. While no dosage amount has been
identified for its potential role in cancer prevention, the Recommended Dietary
Allowance (RDA) for its role in normal cellular function is 55 micrograms (mcg)
for adult men and women. Seafood, meat and grains are the major dietary
sources. You get 35 to 75 mcg in a three-ounce portion of fish, about 25 mcg in
a 3-ounce portion of poultry or meat, and 15-35 mcg in one cup of pasta or rice
or two slices of bread. Vegetables and fruits generally supply only small
amounts that add up as you eat more; one exception is the 18 to 36 mcg in a cup
of cooked mushrooms. Also note that you can get the entire RDA in one Brazil
nut. While most everyone in the U.S. gets well over the RDA, it’s important not
to overdo it. The National Academy of Science warns that too much selenium can
cause nerve damage, hair loss and digestive disturbances. To avoid potential
problems, the maximum amount of selenium (from food and supplements) considered
safe is 400 mcg – a level only likely to be reached with excessive fortified
foods and supplements.
Q: Which cocktail is lower in calories: a martini or a margarita?
A: Each of those drinks can be made in many variations that change
the calorie load.
A small martini might
weigh in with about 120 calories – slightly lower than a margarita – but even a
small addition like lime juice can brings calories closer to 160.
In addition, some people make margaritas with
sweet and sour mix and extra juice, or martinis with extra flavors (chocolate
liqueur, for example), all of which add calories.
And don’t forget that alcohol in itself is a
concentrated source of calories, so increased portions make calories increase
Although one standard drink is
defined as one-and-a-half ounces of 80-proof liquor, many drinks contain double
that amount or more. Just because it’s served in one glass does not mean it’s
considered “one drink.” For weight control (and other health and safety
concerns) be mindful of what and how much you drink, perhaps alternating
alcohol with club soda or other low-calorie, nonalcoholic options.
Publication Date: September 1, 2008
Sarah Wally, (202) 328-7744
The American Institute for Cancer Research
(AICR) is the cancer charity that fosters research on the relationship of
nutrition, physical activity and weight management to cancer risk, interprets
the scientific literature and educates the public about the results. It has
contributed more than $86 million for innovative research conducted at
universities, hospitals and research centers across the country. AICR has
published two landmark reports that interpret the accumulated research in the
field and is committed to a process of continuous review. AICR also provides a
wide range of educational programs to help millions of Americans learn to make
dietary changes for lower cancer risk. Its award-winning New American Plate
program is presented in brochures, seminars and on its Web site, www.aicr.org.
AICR is a member of the World Cancer Research Fund International.
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