Nutrition Hotline: this issue's Nutrition Hotline considers the number of children in the United States who are vegetarian, examines why the amount of calcium in greens varies among sources, and advises vegans with herpes zoster about foods containing lysine and arginine.
J.N., via e-mail
ANSWER: The news story you saw was probably from the Centers for Disease Control and Prevention (CDC). It was based on a study about the use of complementary and alternative medicine by adults and children in the U.S. in 2007. Vegetarian diets are considered to be complementary and alternative medicine, apparently.
Here's how the survey questions for parents of children (<18 years old) were worded.
* "During the past 12 months, did [your child] use a vegetarian diet to treat a specific health problem or condition other than weight control or weight loss?"
* "During the past 12 months, did [your child] use any of the following special diets for two weeks or more for health reasons?" [Vegetarian diet is one of the choices listed.]
As you can see, many parents whose children follow vegetarian diets for religious, ethical, animal rights, environmental, or other masons would answer "no" to these questions and not be counted. We suspect that this is one reason why our most recent poll found that 3 percent of 8- to 18-year-olds are vegetarian. Also, the CDC survey included children age 0 to 17 years. Possibly older children are more likely to follow a vegetarian diet, so differences in ages could explain some of the difference in results between the surveys. Therefore, while the CDC survey does give an indication of how many 0-to 17-year-olds use a vegetarian diet to treat a health problem, it really does not provide an accurate count of how many children are vegetarian.
One other consideration is that the CDC survey left it up to the person being surveyed to define a vegetarian diet. As readers know, this could certainly affect results. The VRG specifically asks if those being surveyed "never" eat meat, fish, or poultry, and those who answer "yes" are counted as vegetarians. We think that this presents a more accurate count of true vegetarians. For more information on polls, see <www. vrg.org/nutshell/faq.htm#poll>.
QUESTION: "I was researching on the web the milligrams of calcium contained in various greens (cooked and raw). When doing this, I noticed variation among sites so I thought I would go to two reputable sources (VRG and the American Dietetic Association) to get the correct answer, but I found variation there, too. Does VRG have a suggestion on which websites to rely upon for milligrams of calcium in various cooked greens?"
G., via e-mail
ANSWER: Because greens are a natural product and are not formulated in a laboratory like, say, a vitamin pill, the amount of any nutrient in them, including calcium, will vary. Factors that can affect this variation include their growing conditions (type of soil, any fertilizers used, amount of nutrients in water used for irrigation or rain water), their storage conditions (which would affect vitamins more than minerals like calcium), the variety of vegetable, any processing, and even what part of the plant is used. For instance, broccoli florets have a different nutrient content than broccoli stems.
When a database of nutrient content of foods is developed, ideally a number of samples of each food are taken and the average value is used in the database. The most respected database is that of the United States Department of Agriculture (USDA). This is where both the American Dietetic Association (ADA) and The VRG go to get the numbers that you see in materials. However, even within the USDA database there can be differences. For instance, the calcium listed for collard greens that are picked and then cooked is lower than that listed for collard greens that are frozen and then cooked. There is no logical explanation for why freezing would 'increase' the amount of calcium in collard greens, so I must conclude that the variation is due to differences in how the collards were grown or their variety. Therefore, depending on which form (raw/cooked versus frozen/cooked) of collard greens a group reported, you would see different values. In addition, the USDA database is updated regularly, so sometimes websites will still have older numbers listed.
We suggest that you use the USDA database. The database is free and is located at <www.nal.usda.gov/ fnic/foodcomp/search/>. It has values for both raw and cooked greens.
QUESTION: "For vegans, there seems to be a problem with lysine versus arginine for those diagnosed with herpes, particularly herpes zoster. Lysine is said to fight herpes, but lists of lysine-rich foods feature meat and especially dairy. Arginine is said to feed herpes, but lists of arginine-rich foods feature all the good foods for vegans. What to eat!? Thanks for any insights."
ANSWER: What we commonly think of as herpes is an infection caused by the Herpes Simplex Virus. Oral herpes causes cold sores around the mouth and face, while genital herpes is a sexually transmitted disease and affects the genital area. Herpes zoster, also called shingles, is caused by a different virus, the Herpes Varicella-Zoster virus. This is the same virus that causes chicken pox.
Lysine, an amino acid, is frequently claimed to control outbreaks of both herpes and shingles. Some studies with lysine supplements (not a high-lysine diet) have shown that lysine supplements can reduce the frequency of recurrences or shorten the time to heal from an outbreak. Other studies, also using lysine supplements, have not shown any benefits. In other words, it is not certain whether lysine can help with herpes. No studies have used high-lysine diets.
A concern with lysine supplements is that taking large amounts of lysine may throw other amino acids out of balance and interfere with the absorption of other nutrients, such as vitamins and minerals.
As far as vegan foods, foods such as tofu and beans especially do provide lysine. While the amounts in a serving of these foods may not be as high as in a serving of meat, a vegan eating reasonable amounts of lysine-containing foods has no trouble getting generous amounts of lysine.
Foods high in arginine are sometimes believed to trigger outbreaks of herpes; however, I could find no scientific studies to support this.
Meats also contain substantially more arginine than vegetarian foods. For example, half a chicken breast has 1.8 grams of arginine, while 1 cup of kidney beans has 0.95 grams. Three ounces of cooked hamburger has 1.34 grams of arginine, while 1 cup of brown rice has 0.38 grams and a cup of broccoli has 0.31 grams.
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|Date:||Jul 1, 2009|
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