Nutrition Overview
Your understanding of nutrition can be your key to optimal health. This
article covers the essential nutrition information that you need for health:
dietary guidelines, dietary reference intakes, food guide pyramid, calories,
carbohydrates, protein, fats, vitamins, minerals, and phytochemicals.
The Council on Food and Nutrition of the American Medical Association defines
nutrition as "the science of food; the nutrients and the substances therein;
their action, interaction, and balance in relation to health and disease; and
the process by which the organism (i.e. body) ingests, digest, absorbs,
transports, utilizes, and excretes food substances." The purpose of our diet is
to consume foods that provide the six essential nutrients: carbohydrates,
protein, fat, vitamins, minerals, and water. The correct amount and variety of
food provides the correct amount of nutrients for health and weight management.
Dietary Reference Intakes
One thing that we all have in common is that we all eat. What, when, why, and
how much we eat varies from person to person. We often choose our foods based on
taste, familiarity, cost, and/or availability. What we choose to eat is not
necessarily what our bodies need us to eat. A diet that is deficient in
nutrients is one that can lead to health and weight problems. Fortunately,
guidelines have been established to assist us with providing our body with the
nutrients that it needs.
Research to determine the appropriate amount of nutrients for health began in
the 1940s. This need arose after men were being rejected from the military
during World War II due to the effects of poor nutrition on their health. The
first Food and Nutrition Board was formed to evaluate the nutrition intakes of
large populations. Since then, the Food and Nutrition Board has undergone many
changes and published comprehensive guidelines on nutrition for disease
prevention.
The latest and most comprehensive nutrition recommendations are contained in
the so-called Dietary Reference Intakes (DRIs). DRIs were created in 1997 and
have changed the way that diets are evaluated. The primary goal of these
guidelines was to not only prevent nutrient deficiencies but also reduce the
risk of chronic diseases such as cancer, cardiovascular disease, and
osteoporosis. DRIs have been set for macronutrients (carbohydrates, proteins,
and fats), micronutrients (vitamins and minerals), electrolytes and water, the
role of alcohol in health and disease, and bioactive compounds such as
phytoestrogens and phytochemicals.
There are four types of DRI reference values:
- Estimated Average
Requirements (EARs): the nutrient intake that is estimated to meet the needs of
50% of the individuals in a given gender and age group
- Recommended Dietary
Allowances (RDAs): These tend to be the most well-known guidelines. They were
set for the nutrient intake that is sufficient to meet the needs of nearly all
individuals (about 97%) in a given gender and age group. Many people often
incorrectly refer to these as the recommended "daily" allowances and believe
that it is their goal to reach the RDA each day. It was not meant to be used as
a guide for an individual's daily needs. The RDAs were established to be used in
setting standards for food-assistance programs, for interpreting food record
consumption of populations, and for establishing guidelines for nutrition
labels.
- Adequate Intakes (AIs): the nutrients for which there is not enough
information to establish an EAR
- Tolerable Upper Limits (Upper Levels or ULs):
a nutrient's maximum level of daily intake that is unlikely to cause adverse
health effects in nearly all individuals (97% to 98%) of the population
Due to the complexity of analyzing diets, the DRIs have been primarily used
by researchers and registered dietitians. The programs used to analyze diets
have now become available to the public. You can keep track of everything that
you eat and drink on one of the internet sites that offer one of these programs,
and you will get detailed information about your intake in comparison to the
DRIs. When keeping track of your diet, you want to use a Web site that uses the
USDA National Nutrient Database for Standard Reference as their source of
nutrition information.
You do not need to reach the guidelines for every nutrient, every day of the
week, so do not be alarmed when you fall short or go over in nutrients every now
and then. But when you are consistently having a problem reaching your
recommendations, it's best to work with a
Dietary Guidelines for Americans
Following a healthy diet can be as simple as following the guidelines, the
Dietary Guidelines for Americans, that is. These guidelines have been updated
and released every five years since 1980 by the U.S. Department of Health and Human
Services (HHS) and the Department of Agriculture (USDA). The goal of these
guidelines is to promote health and reduce the risk for major chronic disease
for people 2 years and older. The Guidelines also address ways to maintain a
healthy weight.
The key recommendations are:
Adequate nutrients within calorie needs:
- Consume a variety of
nutrient-dense foods and beverages within and among the basic food groups while
choosing foods that limit the intake of saturated and trans fats, cholesterol,
added sugars, salt, and alcohol.
- Meet recommended intakes within energy needs
by adopting a balanced eating pattern, such as the USDA Food Guide or the DASH
Eating Plan.
Weight management:
- To maintain body weight in a healthy range,
balance calories from foods and beverages with calories expended.
- To prevent
gradual weight gain over time, make small decreases in food and beverage
calories and increase physical activity.
Physical activity:
- Engage in regular
physical activity and reduce sedentary activities to promote health,
psychological well-being, and a healthy body weight.
- Achieve physical fitness
by including cardiovascular conditioning, stretching exercises for flexibility,
and resistance exercises or calisthenics for muscle strength and endurance.
Food groups to encourage:
- Consume a sufficient amount of fruits and vegetables
while staying within energy needs. For a reference 2,000-calorie intake, 2 cups of fruit and 2½ cups of vegetables
per day are recommended, with higher or
lower amounts depending on the calorie level.
- Choose a variety of fruits and
vegetables each day. In particular, select from all five vegetable subgroups
(dark green, orange, legumes, starchy vegetables, and other vegetables) several
times a week.
- Consume three or more ounce-equivalents of whole-grain products per
day, with the rest of the recommended grains coming from enriched or whole-grain
products. In general, at least half the grains should come from whole grains.
- Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products.
Alcoholic beverages:
- Those who choose to drink alcoholic beverages should do
so sensibly and in moderation -- defined as the consumption of up to one drink per
day for women and up to two drinks per day for men.
- Alcoholic beverages should
not be consumed by some individuals, including those who cannot restrict their
alcohol intake, women of childbearing age who may become pregnant, pregnant and
lactating women, children and adolescents, individuals taking medications that
can interact with alcohol, and those with specific medical conditions.
There are also guidelines for specific population groups like children, adolescents,
pregnant women, breastfeeding women, and older adults. The recommendations for fat,
carbohydrates, sodium, and potassium can be found under their subheadings in
this article.
The guidelines are extensive, but you do not need to meet every
recommendation all at once. To establish a healthy eating plan, the goal is to
begin to make gradual changes to your eating and activity. You can select one or
two guidelines a week or month to focus on. Over time, you will be able to make
most, if not all, of the guidelines a part of your life.
health-care professional
The Food Guide Pyramid
Everyone has heard about the importance of following a balanced diet, but how
do you know what the right balance is? The goal of a balanced diet is to consume
an appropriate amount of calories, carbohydrates, protein, fat, vitamins,
minerals, and water. Food can be divided into food groups according to its
calorie and nutrient content. This means that you can consume any food within a
food group and get a similar amount of nutrients. The amount of calories will
depend on the amount that you consume.
Food guides have been categorizing foods into food groups since 1916 and have
undergone many changes:
- 1916 Caroline Hunt buying guide: five food groups were milk and meat;
cereals; vegetables and fruits; fats and fat foods; and sugars and sugary foods
- 1930's H.K. Stiebeling buying guide: 12 food groups were milk; lean meat,
poultry and fish; dry mature beans, peas, and nuts; eggs; flours and cereals;
leafy green and yellow vegetables; potatoes and sweet potatoes; other vegetables
and fruit; tomatoes and citrus; butter; other fats; and sugars
- 1940's Basic
Seven foundation diet: seven food groups were milk and milk products; meat,
poultry, fish, eggs, dried beans, peas and nuts; bread, flour, and cereals; leafy
green and yellow vegetables; potatoes and other fruit and vegetables; citrus,
tomato, cabbage, and salad greens; and butter-fortified margarine
- 1956-1970's
Basic Four foundation diet: milk group; meat group; bread and cereal; and
vegetable-fruit group
- 1979 Hassle-Free foundation diet: five food groups were
milk-cheese group; meat, poultry, fish, and beans group; bread-cereal group;
vegetable-fruit group; and fats, sweets, and alcohol group
- 1984 to present
Food Guide Pyramid: six food groups were milk, yogurt, and cheese; meat,
poultry, fish, eggs, dry beans, and nuts; breads, cereals, rice, and pasta;
vegetables; fruit; and fats, oils, and sweets
The updates that were recently made to the Food Guide Pyramid are the first
to offer personalized eating plans. Instead of recommendations that give you a
range to follow, you can now get a set number of servings to have from each food
group based on your age, gender, height, and weight .
Another feature of the MyPyramid Plan is the food-gallery section. This
section provides images of the serving sizes of foods in each of the food
groups. Many people complain about serving sizes being too small. Serving size
is a standard unit of measurement, not the amount that you are supposed to
consume. The amount, or number of servings that you consume, is your portion.
For example, if the serving size for pasta is ½ cup and you consume 2 cups, that
means that your portion is 2 cups and you consumed 4 servings.
The food guides have been separating food into food groups for nearly a
century. The current Food Guide Pyramid still emphasizes eating a balanced diet
with foods from each of the food groups, but with today's version of the plan,
you can get a personalized plan instead of just general recommendations. This is
everyone's chance to learn how to eat a well-balanced diet.
Food Labels
The next time that you are about to decide what to eat remember that "it's
what's inside that counts." You can take a look inside by reading what is on the
outside, or the food label. The food label, or nutrition facts label, is your
best source of information for what you are feeding your body. Before you can
use it, you have to know how to read it, so let's "digest" the food label.
The food label provides information about
- serving size,
- calories,
- calories from fat,
- total fat,
- saturated fat,
- monounsaturated fat,
- polyunsaturated fat,
- trans fat,
- cholesterol,
- sodium,
- total carbohydrates,
- dietary fiber,
- sugars,
- protein,
- vitamins, and
- minerals.
The most important thing to read on the food label is the very first line.
The serving size that is listed is what all of the rest of the information is
based upon. For example, if you were looking at a label for cookies and the
serving size was two cookies, all of the nutrition information on the label
would be based on the consumption of two cookies. When you consume more than two
cookies, you need to increase the numbers based on how many servings you
consume. For example, if there are 100 calories in two cookies, and you consume
six cookies, you would be consuming 300 calories.
The information listed below the serving size is listed in grams and
percentages. You will learn how to interpret the grams for each nutrient later
on in the article. In an attempt to help people determine if the food will reach
their nutritional needs, the FDA developed a set of generic standards called
Daily Values. You will only find Daily Values listed on food labels. The
standard DRIs could not be used because they vary by gender and age, so they are
too specific for a food label. The limitation of the Daily Values is that they
are based on a 2,000-calorie diet. This means that the percentages are only
relevant to someone who is consuming 2,000 calories. For everyone else, these
percentages will either be too high or too low. For this reason, it's best to
focus on grams and ingredients.
Calories
You may sometimes count them, cut them, or curse them, but you always need to
consume them. Calories provide the energy that our bodies need to function and
keep us moving. The food that we eat and the beverages that we drink provide
calories.
Your sources of calories comes from three of the essential nutrients:
carbohydrates, protein, and fat. Each of these nutrients has a set number of
calories:
- 1 gram of carbohydrates = 4 calories
- 1 gram of protein = 4
calories
- 1 gram of fat = 9 calories
You may also get calories from alcohol.
- 1 gram of alcohol has 7 calories
You maintain your weight by consuming the right amount of calories, gain
weight with excessive amounts, and lose weight with an inadequate amount. Your
calorie needs are determined by your age, height, weight, gender, and activity
level. You can use the Harris-Benedict Equation or the Mifflin-St. Jeor equation
to calculate the number of maintenance calories you require. The Mifflin-St. Jeor calculation is best for someone who is overweight or obese. Once you know
how many calories you need to maintain your weight, you can determine what it
will take to lose or gain weight. When you go above or below your maintenance
calories by 3,500 calories, you will either gain or lose 1 pound. For example, if
you consumed an extra 500 calories per day, you would gain 1 pound in a week
(500 x 7 = 3,500). The same is true for weight loss. This is why every calorie
counts when it comes to your weight.
The FDA and United States Department of Agriculture (USDA) regulations
require that ingredients be listed in order of their predominance in a food.
This means that the ingredient used in the highest amounts will be listed first.
This poses a problem when a perceived unhealthy ingredient was the predominant
ingredient. For example, when people see sugar as the first ingredient in a
cereal, they may be more likely to consider it unhealthy. The way that food
manufacturers have gotten around this is to use different sources of sugar in
smaller quantities. For example, a food containing 1 cup of sugar may have to
have the sugar listed as the first ingredient, but smaller amounts of different
sources of sugar could be listed throughout the ingredients.
Carbohydrates
The emergence of low-carbohydrate diets has resulted in confusion over
whether carbohydrates are good or bad. Carbohydrates are one of the six
essential nutrients. This means that they are essential for your health, so
there is no way that omitting them from your diet would be beneficial. An excess
intake of any nutrient will cause weight gain. The key is to consume the
appropriate sources and amounts of carbohydrates.
Carbohydrates are the primary source of fuel for your body. Your red blood
cells and most parts of your brain derive all of their energy from
carbohydrates. An adequate consumption of carbohydrates also allows your body to
use protein and fat for their necessary requirements, it prevents ketosis, it
provides fiber, and it's the source of sweetness in your foods.
Carbohydrates are all made up of carbon, hydrogen, and oxygen, but they are
not equal in terms of their nutritional value. This is where the concept of good
and bad carbohydrates probably began. Based on the structure, carbohydrates are
divided into two categories:
1. Simple carbohydrates
- Monosaccharide
- Fructose (fruit sugar)
- Glucose (blood sugar)
- Galactose
(part of milk sugar)
- Disaccharide: two monosaccharides combined
- Sucrose: a combination of
fructose and glucose (table sugar)
- Maltose: a combination of glucose and
glucose
- Lactose: a combination of galactose and glucose (milk sugar)
2. Complex carbohydrates
- Polysaccharide: a combination of thousands of glucose units (starch,
glycogen, fiber)
Ultimately, all of these carbohydrates are broken down and converted into
glucose. Complex carbohydrates take longer to digest and provide fiber, so they
are the best source of carbohydrates. This does not mean that fruit or milk is
not a healthy source. The skin and the seeds in the fruit are sources of fiber,
so they contain both simple and complex carbohydrates. Milk sugar has been shown
to enhance calcium absorption, making it an asset to your health. Again, the
quantity consumed is going to be the key.
Contrary to what many people believe, carbohydrates are found in the majority
of the food groups. They are found in
- grains,
- fruits,
- milk/yogurt, and
- vegetables.
The following are Dietary Guidelines for carbohydrate consumption:
- Choose fiber-rich fruits, vegetables, and whole grains often.
- Choose and prepare foods and beverages with little added sugars or caloric
sweeteners, such as amounts suggested by the USDA Food Guide and the DASH Eating
Plan.
- Reduce the incidence of dental caries by practicing good oral hygiene and consuming sugar-
and starch-containing foods and beverages less frequently.
The following are Dietary Reference Intakes for carbohydrate consumption:
- Adults and children should get 45%-65% of their calories from carbohydrates.
- Added sugars should comprise no
more than 25% of total calories consumed. Added sugars are those incorporated
into foods and beverages during production which usually provide insignificant
amounts of vitamins, minerals, or other essential nutrients. Major sources
include soft drinks, fruit drinks, pastries, candy, and other sweets.
- The
recommended intake for total fiber for adults 50 years and younger is set at 38
grams for men and 25 grams for women, while for men and women over 50 it is 30
and 21 grams per day, respectively, due to decreased food consumption.
The final
verdict on carbohydrates is that you absolutely need them as part of your diet.
You want your sources to be from vegetables, fresh fruit, whole wheat grains,
and dairy products. Your calorie consumption will control your weight, and your
balance of nutrients will control your health.
Proteins
Protein is one nutrient that fad diets have never dared to recommend omitting
from your diet. A deficiency of this nutrient can result in death. As with the
other essential nutrients, we need a set amount of protein for optimal health,
and going above that can cause problems.
Protein has numerous functions in the body:
- Regulates and maintains body functions: blood clotting, fluid balance, and
enzyme and hormone production
- Supports growth and maintenance: hair, skin,
nails, and cells
- Builds antibodies necessary for your immune system
- Provides
energy
Protein deficiencies are referred to as protein-energy malnutrition (PEM).
The two PEM diseases are
- kwashiorkor, which occurs when a diet has a marginal amount of calories and an
insufficient amount of protein; and
- marasmus, which occurs when a diet has an
insufficient amount of calories and protein.
Amino acids are the building blocks for protein. A strand of amino acids that
make up a protein may contain up to 20 different amino acids. They are made up
of carbon, hydrogen, oxygen, and nitrogen. There are essential and nonessential
amino acids. You have to consume the essential ones, while the nonessential ones
can be made by other amino acids when there is a sufficient amount in your diet.
A source of protein that contains all of the essential amino acids is considered
a complete protein. Animal proteins (meat, poultry, seafood, and eggs) fall into
this category. The incomplete proteins (vegetables, grains, and nuts) can become
complete when they are combined. Examples of this are
- beans and rice,
- peanut butter and bread, and
- cereal and milk.
The following are Dietary Reference Intakes for protein consumption:
- Adults and children should get
10%-35% of their calories from protein.
- Using new data, the report reaffirms
previously established recommended levels of protein intake, which is 0.8 grams
per kilogram of body weight for adults; however, recommended levels are increased
during pregnancy.
Your body does not store protein the way that it stores
carbohydrates and fats. This means that your diet is the critical source for this
essential nutrient. More is not better, so there is no need to go above the
recommendations. In fact, research has shown that very high protein diets can
lead to increased calcium loss and weakened bones. Be sure to add a
protein source to each meal to curb your hunger and keep you healthy.
Fats
Dietary fat does not equal body fat. There is a huge misconception that fat
in the diet will always lead to weight gain. As mentioned previously, excess
calories are responsible for weight gain, not any one nutrient. Dietary fat is
essential for our health and should be a part of everyone's diet.
Dietary fat is required for
- energy: Fat is the most concentrated source of calories in the
diet, providing 9 calories per gram compared with 4 calories per gram from
either carbohydrates or protein;
- transport of fat-soluble vitamins: A, D, E,
and K and carotenoids;
- maintenance of healthy skin;
- regulation of cholesterol
metabolism; and
- precursor of prostaglandins (hormone-like substances that regulate
many body functions).
Fat is composed of the same three elements as carbohydrates: carbon,
hydrogen, and oxygen. The fat that we consume is primarily in the source of
triglycerides. This means that there are three fatty acids combined with a
glycerol backbone. These fatty acids are
- monounsaturated: olive oil, olives, peanut oil, canola oil, avocado, and
nuts;
- polyunsaturated: safflower oil, sunflower oil, corn oil, fish, flaxseeds,
and walnuts; and
- saturated: butter, lard, red meat, poultry skin, whole milk, coconut
oil, and palm oil.
Each triglyceride will have varying levels of each one of these fatty acids.
The ones that have a higher percentage of monounsaturated and polyunsaturated
fats are considered the healthiest sources. Some examples are
- olive oil: 15% saturated fat, 10% polyunsaturated fat, and 75% monounsaturated
fat;
- lard: 43% saturated fat, 10% polyunsaturated fat, and 47% monounsaturated fat; and
- flaxseed oil: 9% saturated fat, 73% polyunsaturated fat, and 18% monounsaturated
fat.
Along with these fatty acids, there are also trans fats and cholesterol in
your diet. Trans fat can be found in some margarines, vegetable shortenings,
cookies, crackers, snack foods, and other foods made with or fried in partially
hydrogenated oils. Unlike other fats, the majority of trans fat is formed when
food manufacturers turn liquid oils into solid fats. A small amount of trans fat
is found naturally, primarily in some animal-based foods.
Trans fat has been found to be the most dangerous for our health. It's so
dangerous that the guidelines are not to consume any in your diet. Recently,
trans fat has been added to the food labels so that you can now determine if
there is any present in the food. The one limitation is that you will only see
foods with over 0.5 grams of trans fat per serving list any trans fat on their
label. This means that if the serving size is two cookies and there is .4 grams
of trans fat in two cookies, the trans fat content will be listed as 0 grams.
However, if you eat eight cookies, you will actually be consuming 1.6 grams of trans
fat. The way to determine if there is any trans fat present is to read the list
of ingredients and look for hydrogenated or partially hydrogenated oil.
The cholesterol in your blood comes from your liver and your diet. The
dietary sources are animal foods like meat, poultry, fish, and dairy products.
The reason our livers produce cholesterol is because our body needs it.
Cholesterol is used for producing cell membranes and some hormones, and serves
other needed bodily functions.
The effects that dietary fat has on your blood cholesterol levels will help
you choose which ones to consume. According to the American Heart Association,
LDL (low-density lipoprotein) is the "bad" cholesterol because when too much of
it circulates in the blood, it can slowly build up in the walls of the arteries
that feed the heart and brain. HDL (high-density lipoprotein) is the "good"
cholesterol because it helps remove "bad" cholesterol from arteries and prevent
blockage. The goal is to have a
- total blood cholesterol less than 200 mg/dL;
- LDL less than 100 mg/dL; and
- HDL
greater than 40 mg/dL for men and 50 mg/dL for women.
The effect that your diet has on each of these is
- saturated fat increases total cholesterol and LDL levels: the goal is for
this to be less than 7% of your fat;
- trans fat increases total cholesterol and LDL levels and lowers HDL levels; and
- cholesterol over 300 mg/day can raise total
cholesterol and LDL levels.
While these fats can harm your health, there are fats
that are essential for optimal health. The essential fatty acids are the
polyunsaturated fats omega-3 and omega-6 fatty acids. You need to consume these
because your body cannot produce them. We need an equal amount of each of these
fats. The typical American diet has an abundance of omega-6 fatty acids with a
limited amount of omega-3 fatty acids. On average, Americans consume 11 to 30
times more omega-6 fatty acids than omega-3 fatty acids. Research has shown that
omega-3 fatty acids can reduce blood triglyceride levels, reduce blood pressure,
improve morning stiffness and joint tenderness in rheumatoid arthritis, protect
the heart in people who have had a heart attack, decrease the risk of stroke,
reduce the risk of atherosclerosis, and possibly have an impact on depression.
The dietary sources of omega-3 fatty acids are mackerel, lake trout, herring,
sardines, albacore tuna, and salmon.
Dietary Guidelines for Fat
The following are Dietary Guidelines for fat:
-
Consume less than 10% of calories from saturated fatty acids and less
than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as
possible.
- Keep total fat intake between 20%-35% of calories, with
most fats coming from sources of polyunsaturated and monounsaturated fatty
acids, such as fish, nuts, and vegetable oils.
- When selecting and preparing
meat, poultry, dry beans, and milk or milk products, make choices that are lean,
low-fat, or fat-free.
- Limit intake of fats and oils high in saturated and/or
trans fatty acids, and choose products low in such fats and oils.
The following are Dietary Reference Intakes for fat consumption:
- Adults should get 20%-35% of
their calories from fat.
- Infants and younger children should get 25%-40% of
calories from fat.
- The report doesn't set maximum levels for saturated fat,
cholesterol, or trans fatty acids, as increased risk exists at levels above
zero; however, the recommendation is to eat as little as possible while
consuming a diet adequate in important other essential nutrients.
- Recommendations are made for linoleic acid (an omega-6 fatty acid) and for
alpha-linoleic acid (an omega-3 fatty acid).
Dietary fat is a necessary
nutrient in our diet. Many people have turned to fat-free products, assuming
that they are healthier, but this is not always the case. Fat-free products are
often high in sugar. You may find that you actually need to increase the amount
of fat that you consume. You will need to cut back on another nutrient to avoid
going above your calorie needs. It is also important to focus on the kinds of
fat that you are consuming. Making the change from consumption of saturated and
trans fat to monounsaturated and polyunsaturated fats is lifesaving.
Fat-Soluble Vitamins
Vitamins are needed in small quantities to perform invaluable functions. They
are required for normal function, growth, and maintenance of body tissues.
Without a sufficient quantity of any vitamin, a deficiency will occur with a
subsequent decline in health. Fortunately, a balanced diet is often sufficient
enough to meet your needs.
Vitamins fall into two classes: fat-soluble and water-soluble. Their
solubility will determine how the vitamin is absorbed and transported by the
bloodstream, whether or not it can be stored in the body, and how easily it can
be lost from the body. Requirements for each of the vitamins are based on age,
gender, pregnancy, and lactation. You can find them at
http://www.iom.edu/Object.File/Master/7/296/
webtablevitamins.pdf.
The fat-soluble vitamins are A, D, E, and K. Adequate absorption of these
vitamins is dependent on efficient fat intake and absorption. Except for vitamin
K, fat-soluble vitamins are not easily excreted from the body, so they can be
toxic at excessive levels. The only way to reach toxic levels would be through
taking supplements, not through your diet. This is another case when balance is
the key, and excessive amounts can cause harm.
Vitamin A is abundant in our food supply, so there is little risk of a
deficiency. It is needed for regulation of the immune system, vision,
reproduction, bone growth, cell division, and cell differentiation. A deficiency
will result in night blindness and a decreased immune system, resulting in a
decrease in the ability to fight infections. This can occur from an inadequate
diet, chronic diarrhea, and an excess intake of alcohol. Dietary sources of
vitamin A include
- whole eggs,
- milk,
- liver,
- fortified cereals,
- sweet
potatoes,
- cooked spinach,
- fresh mango,
- cooked acorn squash,
- cooked kale,
- cooked broccoli, and
- margarine.
Vitamin D is supplied by our diet and sunlight. Exposure to ultraviolet (UV)
rays from the sun can trigger the production of vitamin D in our body. The
amount of sun needed will depend on your skin color, age, the time of the day,
season, and geographic location. Experts have recommended that you expose your
hands, face, and arms two to three times a week for about 10 to 15 minutes
without sunscreen.
Vitamin D is needed for healthy bones by maintaining normal blood levels of
calcium and phosphorus and for maintenance of a healthy immune system. A
deficiency in children can result in rickets, and a deficiency in adults can
cause osteomalacia. An inadequate diet, limited exposure to sunlight, and
malabsorption can cause the deficiency. Dietary sources of vitamin D are
- cod
liver oil,
- baked herring,
- salmon,
- canned tuna in oil,
- sardines in oil,
- milk,
- fortified cereals, and
- whole eggs.
Vitamin E has been shown to have a wide array of health benefits, including
prevention of stroke, diabetes, cancer, heart disease, arthritis, cataracts and
improved immune function. With all of the functions that vitamin E has, a
deficiency of it can result in numerous health problems. Fortunately, vitamin E
deficiencies are rare in this country. Impairment in your ability to absorb fat
would put you at risk for a deficiency, so it's important to have your doctor
monitor your levels. Dietary sources of vitamin E are
- almonds,
- sunflower
seeds,
- sunflower oil,
- wheat germ,
- peanut butter,
- avocado,
- hazelnuts,
- broccoli, and
- kiwi.
Vitamin K is probably most well-known by those who take blood-thinning
medications. Vitamin K plays a crucial role in blood clotting and needs to be
monitored when taking these medications. Without vitamin K, your blood would not
clot, so it is essential for everyone. Vitamin K is also needed for bone
proteins. Some vitamin K can be made in the intestines. When people take
antibiotics that kill the beneficial and harmful bacteria in the intestines, it
puts them at risk for a vitamin K deficiency. Dietary sources of vitamin K
include
- kale,
- spinach,
- turnip greens,
- collards,
- Swiss chard,
- parsley,
- mustard greens, and
- Brussels sprouts.
Water-Soluble Vitamins
The water-soluble vitamins are B and C. Their solubility means that they can
leech into water that they are washed, stored, and cooked in and can be excreted
in the urine. They are associated with some of the most well-known deficiency
diseases. When consumed in adequate amounts, they play an essential role in our
health.
There are numerous B vitamins. Each one of them facilitates energy release in
every cell, so a deficiency affects the entire body. Fortunately, deficiencies
are rare when a diet is well balanced. These are the various B vitamins:
- Thiamin:
Also known as vitamin B1, thiamin is involved in nervous-system and muscle
functioning, the flow of electrolytes in and out of nerve and muscle cells,
carbohydrate metabolism, and the production of hydrochloric acid. Very little
thiamin is stored in the body, so depletion can occur in a little as 14 days.
Chronic alcohol intake and an inadequate diet can lead to a thiamin deficiency.
Beriberi is the deficiency disease for thiamin. Sources of thiamin are pork
chops, sunflower seeds, green peas, baked potatoes, and enriched and whole grain
cereals and pastas.
- Riboflavin: This B vitamin also plays a role in energy
metabolism. It has similar function and sources as thiamin, so a deficiency in
one usually means a deficiency in the other. Additional sources of riboflavin
are milk and milk products and beef liver.
- Niacin: Along with its role in
energy metabolism, niacin is also responsible for the synthesis and breakdown of
fatty acids. Pellagra is the deficiency disease for niacin. Because the primary
source of niacin is dairy products, poultry, fish, lean meats, nuts, and eggs,
deficiencies can be found among the poor as well as in alcoholics.
- Folate:
This vitamin became a mandatory addition to certain foods due to its role in
producing and maintaining new cells. The folate fortification project was
implemented for the protection of developing fetuses. A folate deficiency in a
woman who is pregnant can cause neural tube defects that result in malformations
of the spine (spina bifida), skull, and brain (anencephaly). Since the
fortification of foods with folate began, the incidence of these defects has
declined. Dietary sources of folate are fortified cereals, beef liver, pinto
beans, lentils, spinach, asparagus, avocados, and broccoli.
- Vitamin B12: Like
folate, vitamin B12 is needed for producing and maintaining new cells. It is
also needed to maintain the sheaths that surround and protect nerve fibers. An
inadequate amount of B12 causes pernicious anemia. Signs of vitamin B12
deficiency are fatigue, weakness, constipation, loss of appetite, weight loss,
and numbness and tingling in the hands and feet. An excess intake of folate can
mask the symptoms of B12 deficiency, so it's important to have your levels
checked by a blood test, especially if you consume a vegetarian diet. Vitamin
B12 is found in animal products like trout, salmon, beef, and dairy foods. There
are fortified cereals that provide B12 as well.
Vitamin C is needed to form collagen in bones, cartilage, muscle, and blood
vessels, and aids in the absorption of iron. Vitamin C deficiency was discovered
in sailors more than 200 years ago. This deficiency, later called scurvy, was
killing sailors who stayed out on the sea for long voyages. Initial symptoms of
scurvy in adults may include loss of appetite, diarrhea, shortness of breath,
weakness, and fever, followed by irritability, depression, leg pain,
pseudoparalysis, swelling over long bones of the body, anemia, paleness, poor
wound healing, corkscrew hair, dry eyes, skin thickening (hyperkeratosis), and
bleeding (particularly gum bleeding, bleeding behind the eyes causing
prominence, bleeding at the joints of the ribs and sternum causing discoloration
under the skin of the chest, skin bruising, or blood in the urine or stool).
Scurvy can now be prevented with an adequate diet. Dietary sources of vitamin C
include fruits and vegetables, particularly citrus fruits such as oranges,
limes, and lemons.
Minerals
Minerals are another component in a healthy diet. There are two categories of
minerals: major minerals and trace minerals. The difference between each of
these is the amount that is needed each day. The major minerals are calcium,
phosphorus, magnesium, sodium, potassium, chloride, and sulfur. The trace
minerals are iodine, iron, zinc, selenium, fluoride, chromium, and copper.
The primary functions and sources of the major minerals are
- Calcium: The
primary mineral in bones and teeth is also needed for normal muscle
contraction and relaxation, nerve functioning, and blood clotting. The dietary
sources are milk and milk products, oysters, small fish, tofu, greens, and
legumes.
- Phosphorus: This mineral makes up about 1% of your body weight. It is
needed for bone and tooth strength, and it plays an important role in the body's
utilization of carbohydrates and fats and in the synthesis of protein and in the
maintenance and repair of cells and tissues. The dietary sources are dairy
products and meat.
- Magnesium: This is required for nerve and heart function,
bone strength, and to maintain a healthy immune system. The dietary sources are
halibut, nuts, spinach, cereal, oatmeal, potato, peanut butter, and yogurt.
- Sodium: This is critical for nerve impulse transmission and helps to maintain
cells' normal fluid balance. The guidelines for sodium consumption are to
consume less than 2,300 mg (approximately 1 tsp of salt) of sodium per day and
to choose and prepare foods with little salt. At the same time, consume
potassium-rich foods, such as fruits and vegetables.
- Potassium: This is
essential for the body's growth and maintenance and the contraction of muscles.
It's also necessary to maintain a normal fluid balance between the cells and
body fluids. Dietary sources are potato with the skin, prunes, raisins, lima
beans, orange juice, tomato juice, acorn squash, bananas, spinach, and sunflower
seeds.
- Chloride: Chloride is a part of the hydrochloric acid in the stomach
that is necessary for proper digestion. The dietary sources are salt and
processed foods.
- Sulfur: This is the only mineral that aids in drug
detoxification. The dietary sources are all protein-containing foods.
The primary functions and sources of the trace minerals are
- Iodine: This
mineral is a component of thyroid hormones. The dietary sources are iodized
salt, seafood, and dairy products.
- Iron: Iron deficiency is considered the
number-one nutritional disorder in the world. It is needed to make hemoglobin,
which is used to carry oxygen in the blood. When oxygen can't get to the cells,
the symptoms will be fatigue, poor work performance, and decreased immunity. The
dietary sources are liver, oysters, beef, turkey, chicken, and tuna.
- Zinc:
This mineral is involved in normal growth and development, it's needed for a
healthy immune system, it helps maintain your sense of taste and smell, and it
is needed for wound healing. The dietary sources are seafood, meat, poultry, and
whole grains.
- Fluoride: Pick up your toothpaste and you will see that it
contains fluoride. The reason for this is because it increases resistance of
tooth enamel to dental caries. Water is also fluoridated for this reason.
- Chromium: This mineral enhances the action of insulin. It also appears to be
involved in carbohydrate, protein, and fat metabolism. Dietary sources are meat,
unrefined grains, broccoli, garlic, and basil.
- Copper: Copper aids in forming
hemoglobin, which is needed to carry oxygen to the cells. It is also involved in
protein metabolism and hormone synthesis. The dietary sources are liver, cocoa,
beans, nuts, whole grains, and dried fruits.
I want to conclude with a very important point. The goal isn't to go for
"perfection" with your diet. The goal is to make some changes to what you are
currently doing and continue to add and remove things as you go. There are not
"good" and "bad" foods. Each food can fit into your diet, but the frequency and
quantity may need to be altered. Think of foods as "everyday" foods and
"sometimes" foods, and go for lots of color and a balance of foods from each of
the food groups. Bon appétit.
