Archive for May 12th, 2009

Adolescence is the transition period between childhood and adulthood, a
time of life that begins at puberty. For girls, puberty typically occurs be-tween ages 12 and 13, while for boys it occurs between ages 14 and 15. It
is one of the fastest growth periods of a person’s life. During this time, physical
changes affect the body’s nutritional needs, while changes in one’s
lifestyle may affect eating habits and food choices. Nutritional health during
adolescence is important for supporting the growing body and for preventing
future health problems.
Increased Nutritional Needs
The physical changes of adolescence have a direct influence on a person’s
nutritional needs. Teenagers need additional calories, protein, calcium,
and iron.
Calories. Adolescents need additional calories to provide energy for
growth and activity. Boys ages 11 to 18 need between 2,500 and 2,800 calories
each day. Adolescent girls need approximately 2,200 calories each day.
This is a significant increase from childhood requirements. To meet these
calorie needs, teens should choose a variety of healthful foods, such as lean
protein sources, low-fat dairy products, whole grains, fruits, and vegetables.
Protein. Protein is important for growth and maintenance of muscle. Adolescents
need between 45 and 60 grams of protein each day. Most teens easily
meet this requirement with their intake of beef, pork, chicken, eggs, and
dairy products. Protein is also available from certain vegetable sources, including
tofu and other soy foods, beans, and nuts.
Calcium. Adequate calcium intake is essential for development of strong
and dense bones during the adolescent growth spurt. Inadequate calcium
intake during adolescence and young adulthood puts individuals at risk for
developing osteoporosis later in life. In order to get the required 1,200 milligrams
of calcium, teens are encouraged to consume three to four servings
of calcium-rich foods each day. Good sources include milk, yogurt, cheese,
calcium-fortified juices, and calcium-fortified cereals.
Iron. As adolescents gain muscle mass, more iron is needed to help their
new muscle cells obtain oxygen for energy. A deficiency of iron causes anemia,
which leads to fatigue, confusion, and weakness. Adolescent boys need
12 milligrams of iron each day, while girls need 15 milligrams. Good sources
of iron include beef, chicken, pork, legumes (including beans and peanuts),
enriched or whole grains, and leafy green vegetables such as spinach, collards,
and kale.
Eating and Snacking Patterns
Adolescents tend to eat differently than they did as children. With afterschool
activities and active social lives, teens are not always able to sit down
for three meals a day. Busy schedules may lead to meal skipping, snacking
throughout the day, and more eating away from home. Many teens skip
breakfast, for example, but this meal is particularly important for getting
enough energy to make it through the day, and it may even lead to better
academic performance. When teens skip meals, they are more likely to grab
fast food from a restaurant, vending machine, or convenience store. These
foods are high in fat and sugar and tend to provide little nutritional value.
In addition, eating too many fast foods can lead to weight gain and, in some
cases, diabetes and heart disease.

Eating meals and snacking away from home puts the responsibility for
good food choices right in adolescents’ hands. Snacks should be low in both
fat and added sugar. Some healthful snack ideas include fresh fruit, sliced
vegetables with low-fat dip, low-fat yogurt, low-fat string cheese, peanut
butter and crackers, baked chips, granola bars, and graham crackers. Juices,
fruit drinks, and sodas are usually very high in calories from natural or
added sugar, so they should be consumed in moderation. The Food Guide
Pyramid is an appropriate guide for adolescents’ food choices, even when
snacking.
Potential Nutrition-Related Problems
Adolescents are at risk for obesity, obesity-related chronic diseases, and
eating disorders.
Obesity, Diabetes, and Heart Disease. All over the world, adolescent
obesity is on the rise. This has led to an increase in obesity-related diseases
like diabetes and heart disease. Experts believe this rise in obesity is
due to lack of physical activity and an increase in the amount of fast food
and “junk food” available to adolescents. Staying active and eating foods that
are low in fat and sugar promote a healthy weight for teens.
Eating Disorders. Adolescents tend to be very conscious of appearances
and may feel pressure to be thin or to look a certain way. Fear of gaining
weight may lead to overly restrictive eating habits. Some teens resort to selfinduced
vomiting or laxative use to control their weight. Both boys and girls
are affected by eating disorders. Teens who suspect they have a problem
with body image or eating habits should talk to a trusted adult.
High-Risk Groups
Certain groups of adolescents may be at risk for nutritional inadequacies.Pregnant Teens. When a teenager becomes pregnant, she needs enough
nutrients to support both her baby and her own continued growth and
physical development. If her nutritional needs are not met, her baby may
be born with low birth weight or other health problems. For the best outcome,
pregnant teens need to seek prenatal care and nutrition advice early
in their pregnancy.
Athletes. Adolescents involved in athletics may feel pressure to be at a particular
weight or to perform at a certain level. Some young athletes may be
tempted to adopt unhealthful behaviors such as crash dieting, taking supplements
to improve performance, or eating unhealthful foods to fulfill their
hearty appetites. A balanced nutritional outlook is important for good health
and athletic performance.
Vegetarians. A vegetarian diet can be a very healthy option. However,
adolescents who follow a vegetarian diet, whether for religious or personal
reasons, need to carefully plan their intake to get the protein and minerals
they need. Strict vegetarians (those who do not eat eggs or dairy products),
also known as vegans, may need nutritional supplements to meet their needs
for calcium, vitamin B12, and iron.
Conclusion
Adolescence is a time of growing up both physically and socially. During
these years, the nutrition choices people make will affect not only their current
health, but their future health as well.

Additives and Preservatives
Additives are defined by the United States Food and Drug Administration
(FDA) as “any substance, the intended use of which results or may reasonably
be expected to result, directly or indirectly, in its becoming a component
or otherwise affecting the characteristics of any food.” In other words,
an additive is any substance that is added to food. Direct additives are those
that are intentionally added to foods for a specific purpose. Indirect additives
are those to which the food is exposed during processing, packaging,
or storing. Preservatives are additives that inhibit the growth of bacteria,
yeasts, and molds in foods.
Additives and preservatives have been used in foods for centuries. When
meats are smoked to preserve them, compounds such as butylated hydroxyanisole
(BHA) and butyl gallate are formed and provide both antioxidant
and bacteriostatic effects. Salt has also been used as a preservative for centuries.
Salt lowers the water activity of meats and other foods and inhibits
bacterial growth. Excess water in foods can enhance the growth of bacteria,
yeast, and fungi. Pickling, which involves the addition of acids such as vinegar,
lowers the pH of foods to levels that retard bacterial growth. Some
herbs and spices, such as curry, cinnamon, and chili pepper, also contain antioxidants
and may provide bactericidal effects.

Uses of Additives and Preservatives in Foods
Additives and preservatives are used to maintain product consistency and
quality, improve or maintain nutritional value, maintain palatability and
wholesomeness, provide leavening, control pH, enhance flavor, or provide
color. Food additives may be classified as:
1. Antimicrobial agents, which prevent spoilage of food by mold or microorganisms.
These include not only vinegar and salt, but also compounds
such as calcium propionate and sorbic acid, which are used in
products such as baked goods, salad dressings, cheeses, margarines, and
pickled foods.
2. Antioxidants, which prevent rancidity in foods containing fats and damage
to foods caused by oxygen. Examples of antioxidants include vitamin
C, vitamin E, BHA, BHT (butylated hydroxytolene), and propyl
gallate.
3. Artificial colors, which are intended to make food more appealing and
to provide certain foods with a color that humans associate with a particular
flavor (e.g., red for cherry, green for lime).
4. Artificial flavors and flavor enhancers, the largest class of additives, function
to make food taste better, or to give them a specific taste. Examples
are salt, sugar, and vanilla, which are used to complement the flavor
of certain foods. Synthetic flavoring agents, such as benzaldehyde
for cherry or almond flavor, may be used to simulate natural flavors.
Flavor enhancers, such as monosodium glutamate (MSG) intensify the
flavor of other compounds in a food.
5. Bleaching agents, such as peroxides, are used to whiten foods such as
wheat flour and cheese.
6. Chelating agents, which are used to prevent discoloration, flavor
changes, and rancidity that might occur during the processing of foods.
Examples are citric acid, malic acid, and tartaric acid.
7. Nutrient additives, including vitamins and minerals, are added to foods
during enrichment or fortification. For example, milk is fortified with
vitamin D, and rice is enriched with thiamin, riboflavin, and niacin.
8. Thickening and stabilizing agents, which function to alter the texture of
a food. Examples include the emulsifier lecithin, which, keeps oil and
vinegar blended in salad dressings, and carrageen, which is used as a
thickener in ice creams and low-calorie jellies.
Regulating Safety of Food Additives and Preservatives
Based on the 1958 Food Additives Amendment to the Federal Food, Drug,
and Cosmetic (FD&C) Act of 1938, the FDA must approve the use of all
additives. The manufacturer bears the responsibility of proving that the additive
is safe for its intended use. The Food Additives Amendment excluded
additives and preservatives deemed safe for consumption prior to 1958, such
as salt, sugar, spices, vitamins, vinegar, and monosodium glutamate. These
substances are considered “generally recognized as safe” (GRAS) and may
be used in any food, though the FDA may remove additives from the GRAS
list if safety concerns arise. The 1960 Color Additives Amendment to the
FD&C Act required the FDA to approve synthetic coloring agents used in foods, drugs, cosmetics, and certain medical devices. The Delaney Clause,
which was included in both the Food Additives Amendment and Color Additives
Amendment, prohibited approval of any additive that had been found
to cause cancer in humans or animals. However, in 1996 the Delaney Clause
was modified, and the commissioner of the FDA was charged with assessing
the risk from consumption of additives that may cause cancer and making
a determination as to the use of that additive.
The FDA continually monitors the safety of all food additives as new
scientific evidence becomes available. For example, use of erythrosine
(FD&C Red No. 3) in cosmetics and externally applied drugs was banned in 1990 after it was implicated in the development of thyroid tumors in male
rats. However, the cancer risk associated with FD&C Red No. 3 is about 1
in 100,000 over a seventy-year lifetime, and its use in some foods, such as
candies and maraschino cherries, is still allowed. Tartrazine (FD&C Yellow
No. 5) has been found to cause dermatological reactions ranging from itching
to hives in a small population subgroup. Given the mild nature of the
reaction, however, it still may be used in foods.
Nitrites are also a controversial additive. When used in combination
with salt, nitrites serve as antimicrobials and add flavor and color to meats.
However, nitrite salts can react with certain amines in food to produce nitrosamines,
many of which are known carcinogens. Food manufacturers
must show that nitrosamines will not form in harmful amounts, or will be
prevented from forming, in their products. The flavoring enhancer MSG is
another controversial food additive. MSG is made commercially from a natural
fermentation process using starch and sugar. Despite anecdotal reports
of MSG triggering headaches or exacerbating asthma, the Joint Expert
Committee on Food Additives of the United Nations Food and Agriculture
Organization, the World Health Organization, the European Community’s
Scientific Committee for Food, the American Medical Association, and the
National Academy of Sciences have all affirmed the safety of MSG at normal
consumption levels.
In the United States, food additives and preservatives play an important
role in ensuring that the food supply remains the safest and most abundant in
the world. A major task of the FDA is to regulate the use and approval of thousands
of approved food additives, and to evaluate their safety. Despite consumer
concern about use of food additives and preservatives, there is very little
scientific evidence that they are harmful at the levels at which they are used.
In Europe, food additives and preservatives are evaluated by the European
Commission’s Scientific Committee on Food. Regulations in European
Union countries are similar to those in the United States. The Food
and Agricultural Organization (FAO) of the United Nations and the World
Health Organization (WHO) Expert Committee on Food Additives work
together to evaluate the safety of food additives, as well as contaminants,
naturally occurring toxicants, and residues of veterinary drugs in foods. Acceptable
Daily Intakes (ADIs) are established on the basis of toxicology and
other information.

Food addiction is a nonmedical term that refers to a compulsion to eat specific
foods, usually those that are high in sugar or starch. Although this term
is used to describe intense cravings to seek out specific foods, these foods
are not, in and of themselves, physically addictive in the way a drug might
be. Instead, the need to pursue and consume these foods may be representative
of a psychological disturbance, extreme anxiety, or emotional distress.
SEE ALSO Eating Disorders; Eating Disturbances.

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