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Potatoes are a very common food in the diets of most Europeans,
but perhaps sometimes the nutrition contribution of this staple crop
is overlooked. To start with, there are considerable nutritional differences
between potato dishes depending on how they are cooked, and this may have an
impact on how potatoes as a food are perceived by consumers. What makes
potatoes special is that they combine the characteristics of starchy foods with
those of vegetables.
·
First imported from South America in the 16th century,
potatoes took another 150 years before actually becoming one of the most
important staple food crops in Europe. Nowadays, Central and Eastern Europeans
are the highest consumers, but potatoes play a role in diets all across the
continent, with an average per capita consumption of 94 kg in 2005.1 Listed
below are important and interesting nutritional aspects that are worth
considering in the discussion on the contribution of potatoes towards a healthy
balanced diet.2
·
When boiled or baked, potatoes are a virtually fat-free food. The
main energy-providing nutrient in potatoes is carbohydrate, in the
form of starch. Carbohydrates are the primary source of energy for the
body, and should supply at least half of your calories for the day. The
advantage of getting carbohydrates from potatoes is that you will be getting a
considerable amount of certain micronutrients as well. Potatoes contain a small
amount of protein: about 3 g in a boiled medium portion of 180 g (see Table 1).
Although this is less than 10% of the daily adult requirement, potatoes are a
good source of the amino acids lysine and tryptophan and combined with milk or
eggs make for a high quality protein food.
·
Potatoes are a source of fibre, which contributes to the feeling
of fullness, and supports healthy digestive functions. A 180 g portion of
boiled potatoes provides about 3 grams of fibre, which equates to more than 10%
of the daily recommended intake of fibre, namely 25 grams.3 Some
people enjoy the stronger taste of eating cooked potatoes with skins on, and in
this form they contain even more fibre. However care must be taken not to eat
skins that are discoloured or marked. Green patches indicate higher levels of
glycoalkaloids such as solanine, which may lead to ill health if consumed in
large amounts. A small amount of the starch in potatoes resists
digestion (this is called ‘resistant starch’): this particularly occurs when
potatoes are eaten cold after being cooked, such as in a potato salad.
Resistant starch acts in the body in a similar way to fibre, and may aid in the
control of blood glucose and blood lipid levels.4
·
Potatoes are a steady reliable source of vitamin C – a
medium boiled potato (180 g) contains about 10 mg, which is about one eighth of
the adult requirement. New potatoes contain about double this level, so a
typical serving contains about a quarter of the adult requirement of vitamin C.
Although there are many fruits and juices that contain vitamin C, none of the
other starchy foods that are typically consumed
are significant sources in the way that potatoes are. Although
vitamin C is sensitive to heat, and breaks down to some degree on cooking,
enough is still retained to make cooked potatoes a useful source of this
nutrient. Vitamin C is required for healthy skin, teeth, gums, muscles and
bones, and it also helps with the absorption of iron from plant
foods, which is poorly available to the body otherwise. Furthermore, vitamin C
acts as an antioxidant in the body, and some potatoes with yellow,
orange or purple flesh, specifically also sweet potatoes, contain significant
amounts of other antioxidants such as carotenes or flavonoids.
·
There are several different B group vitamins, and potatoes are a
source of some of these. A medium serving of boiled potatoes (180 g) contains
more than one sixth of the adult daily requirements for vitamins B1, B6 and
folate. These B group vitamins have many functions in the body including being
essential components in the metabolism of carbohydrates to provide energy, and
maintaining a healthy skin and nervous system. Folate is needed
for cell growth and development, which is why ensuring adequate
intakes before and during pregnancy is especially important. Folate is also
essential for the production of red blood cells.
·
Potatoes are a significant source of
the mineral potassium, and also contain small amounts of magnesium
and iron. Potassium has many functions in the body including muscle function
and contraction, the transmission of nerve impulses, and the regulation of
blood pressure. Potatoes contain amounts of potassium that match those in most
fruits and vegetables per unit weight, and because potatoes are typically
consumed in greater quantities, they are an important and reliable food source
of this nutrient. A boiled medium portion of potatoes (180 g) also provides
about one tenth of an adult’s daily requirement of magnesium and iron.
·
Potatoes naturally contain almost no sodium (which together with
chloride forms salt). Public health advice is to be careful not to
consume too much salt, because of an association between sodium
intake and the risk of high blood pressure (hypertension).
Other starchy foods are equally low in sodium, but the potassium content in
potatoes is significantly higher than in, for instance, pasta. The combination
of a high potassium and a low sodium content makes potatoes a healthy food for
people trying to manage their blood pressure. However, caution needs to be
taken not to add a lot of salty condiments or sauces during food preparation.
·
For those who are trying to lose weight, or avoid weight gain,
potatoes may play a helpful role. A medium serving of boiled, peeled potatoes
(180 g) contains about 140 calories, which is much less than the energy content
in the same amount of boiled pasta (286 calories) or boiled rice (248
calories). However, slimmers need to beware: the energy content of potatoes
that have been (deep-)fried can be two or three times higher than for boiled or
baked potatoes, so these forms of potatoes are less suitable for those on a
weight loss diet.
·
Further “good news” for those trying to avoid weight gain, is that
potatoes have a high satiety index. Because the energy density, i.e.
calories per gram of food, of boiled or baked potatoes is low, eating lots of
them does not equate to a large calorie intake (approximately 140
kcal from a medium sized portion). Therefore, it can help you to feel full
without overeating energy-wise. One study of the satiety effects of different
foods reported potatoes as having three times the satiety rating compared to
the same intake of calories from white bread.5
·
Because of the diversity of ways in which potatoes are prepared,
the nutritional content of potato meals is very variable. Nutrient losses
through cooking depend on the temperature and the length of cooking time.
Water-soluble vitamins and minerals such as B vitamins, vitamin C and potassium
leech out from the potatoes into cooking water when boiled. Boiling potatoes
with their skins on (although after cooking they might be peeled and eaten
without skin) greatly reduces these nutrient losses. There is also some loss of
nutrients during storage, and general advice is that potatoes should be kept in
dry, dark and cool conditions. However, potatoes should not be stored at
temperatures as low as 4°C as this may increase the formation of acrylamide
when fried.6 Potatoes that develop green patches or start to sprout
during storage, should be carefully trimmed and peeled, or not consumed.
Although the fat content is very low in potatoes, potato dishes may
be calorie-rich if fat is added during preparation of these. This is the case
of e.g. (deep-)fried potatoes and gratins prepared with full-fat cream and
cheese.
· A very small number of people are not able to tolerate gluten, which is a protein found in wheat and rye. For people who need to follow a gluten-free diet, and so cannot eat many common foods including bread, pasta and most breakfast cereals, potatoes are a very important food. Potatoes are gluten-free and therefore can be consumed freely by people who need to avoid gluten, or who may have other concerns about consuming wheat.
Adult nutrition
·
Every day we are bombarded with nutrition and health
messages and a seemingly endless array of concerns about lifestyle and diet.
Healthy eating and a healthful way of life are important to how we look, feel
and how much we enjoy life. The right lifestyle decisions, with a routine of
good food and regular exercise, can help us make the most of what life has to
offer. Making smart food choices early in life and through adulthood can also
help reduce the risk of certain conditions such as obesity, heart
disease, hypertension, diabetes, certain cancers and osteoporosis.
1. Key factors of a healthy diet
.1. Enjoy the wide
variety of foods
This concept is the most consistent health message in dietary
recommendations around the world. We need more than 40 different nutrients for
good health and no single food can supply them all. That's why consumption of a
wide variety of foods (including fruits, vegetables, cereals and grains, meats,
fish and poultry, dairy products and fats and oils), is necessary for good
health and any food can be enjoyed as part of a healthy diet. Some studies have
linked dietary variety with longevity. In any event, choosing a variety of
foods adds to the enjoyment of meals and snacks.
1.2. Eat regularly
Eating is one of the life's great pleasures and its important to
take time to stop, relax and enjoy mealtimes and snacks. Scheduling eating
times also ensures that meals are not missed, resulting in missed nutrients
that are often not compensated for by subsequent meals. This is especially
important for school children, adolescents and the elderly.
Breakfast is particularly important as it helps kick-start the
body by supplying energy after the all-night fast. Breakfast also appears to
help control weight. All mealtimes offer the opportunity for social and family
interaction. So whether it is three square meals or six mini-meals or snacks,
the aim is to make healthy choices you can enjoy.
1.3. Balance and
moderation
Balancing your food intake means getting enough, but not too much,
of each type of nutrient. If portion sizes are kept reasonable, there is no
need to eliminate favourite foods. There are no "good" or
"bad" foods, only good or bad diets. Any food can fit into a healthy
lifestyle by remembering moderation and balance.
Moderate amounts of all foods can help ensure that energy
(calories) intake is controlled and that excessive amounts of any one food or
food component are not eaten. If you choose a high fat snack, choose a lower
fat option at the next meal. Examples of reasonable serving sizes are 75 -100
grams (the size of a palm) of meat, one medium piece of fruit, ½ cup raw pasta
or one scoop of ice cream (50g). Ready-prepared meals offer a handy means of
portion control and they often have the energy (calorie) value listed on the
pack.
1.4. Maintain a
healthy body weight and feel good
A healthy weight varies between individuals and depends on many
factors including gender, height, age and heredity.
Excess body fat results when more calories are eaten than are
needed. Those extra calories can come from any source - protein, fat,
carbohydrate or alcohol - but fat is the most concentrated source of calories.
Physical activity is a good way of increasing the energy
(calories) expended and it can also lead to feelings of well-being. The message
is simple: if you are gaining weight eat less and be more active.
1.5. Don't forget
your fruits and vegetables
Many Europeans do not meet the recommendations for at least five
servings of fruits and vegetables daily. Numerous studies have shown an
association between the intake of these foods and a decreased risk of cardiovascular
disease and certain cancers. An increased intake of fruits and vegetables has
also been associated with decreased blood pressure. People can fill up on fresh
fruit and vegetables because they are good sources of nutrients and the
majority are naturally low in fat and calories.
Nutritionists are paying much more attention to fruits and
vegetables as "packages" of nutrients and other constituents that are
healthful for humans. The "antioxidant hypothesis" has drawn
attention to the role of micronutrients found in fruits and vegetables like
vitamins C and E , as well as a number of other natural protective substances.
The carotenes (beta-carotene, lutein and lycopene), the flavonoids (phenolic
compounds that are widespread in commonly consumed fruits and vegetables such
as apples and onions and beverages derived from plants like tea, cocoa and red
wine) and the phytoestrogens (principally isoflavones and lignans), are being
demonstrated to have beneficial roles in human health.
1.6. Base the diet
on foods rich in carbohydrates
Most dietary guidelines recommend a daily diet in which at least
55% of the total calories come from carbohydrates. This means making more than
half of our daily food intake should consist of carbohydrate-containing foods
such as grains, pulses, beans, fruits, vegetables and sugars. Choosing
wholegrain bread, pasta and other cereals will help to boost fibre intake.
Although the body treats all carbohydrates in the same way
regardless of their source, carbohydrates are often split into
"complex" and "simple" carbohydrates. Complex carbohydrates
that come from plants are called starch and fibres, and these are found for
example in cereal grains, vegetables, breads, seeds, legumes and beans. These
carbohydrates consist of long strands of many simple carbohydrates linked
together. Simple carbohydrates (sometimes called simple sugars) are found for
example in table sugar, fruits, sweets, jams, soft drinks, fruit juices, honey,
jellies and syrups. Both complex and simple carbohydrates provide the same
amount of energy (4 calories per gram) and both can contribute to tooth decay,
especially when oral hygiene is poor.
1.7. Drink plenty
of fluids
Adults need to drink at least 1.5 litres of fluid daily, even more
if its hot or they are physically active. Plain water is a good source of
liquid but variety can be both pleasant and healthy. Alternative sources are
juices, soft drinks, tea, coffee and milk.
1.8. Fats in
moderation
Fat is essential for good health. Fats provide a ready source of
energy and enable the body to absorb, circulate and store the fat-soluble
vitamins A, D, E and K. Fat-containing foods are needed to supply
"essential fatty acids" that the body cannot make. For example,
oil-rich fish and fish oil supplements are rich sources of the omega-3
polyunsaturated fatty acids (n-3 PUFAs) alpha linolenic acid (ALA),
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These, along with
omega-6 polyunsaturated fatty acids (n-6 PUFAs) such as linoleic acid (LA) and
arachidonic acid (AA), must be consumed in the diet.
Too much fat however, especially saturated fats, can lead to
adverse health effects such as overweight and high cholesterol and increase the
risk of heart disease and some cancers.
Limiting the amount of fat, especially saturated fat in the diet
-but not cutting it out entirely- is the best advice for a healthy diet. Most
dietary recommendations are that less than 30% of the day's total calories
should come from fat and less than 10% of the day's total calories should come from
saturated fat.
1.9. Balance the
salt intake
Salt (NaCl) is made up of sodium and chloride. Sodium is
a nutrient and is present naturally in many foods. Sodium and
chloride are important in helping the body to maintain fluid balance and to
regulate blood pressure.
For most people, any excess sodium passes straight through the
body however in some people it can increase blood pressure. Reducing the amount
of salt in the diet of those who are sensitive to salt may reduce the risk of
high blood pressure. The relationship between salt intake and blood pressure is
still unclear and individuals should consult their doctor for advice.
1.10. Start now -
and make changes gradually
Making changes gradually, such as eating one more fruits/portion of vegetables each day, cutting back on portion sizes, or taking the stairs instead of the lift, means that the changes are easier to maintain.
