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Crossing
Antarctica entirely unassisted demands very complex fine-tuning. The
food taken on the expedition must be both balanced, sufficiently bulky
to cover the particularly high needs for energy, and the weight and
volume to be taken must be reduced to the minimum.
With the help of specialists from specific disciplines as varied
as sports nutrition or human engineering, as well as aspects of
human nutrition and relevant food technology and packaging, they
have been able to put together a plan covering all the required
criteria.
Polar Dietary Requirements
The climatic conditions in the Antarctic mean that individuals have
to survive in extreme temperatures which fluctuate from between -20°C
and -50°C. Even with the best possible clothing, calorific loss
necessitates a substantial surplus of nutritional energy. In temperatures
such as these, a supplement of 1500 Kcal per day needs to be included
to compensate for losses caused by the cold.
The ration for a polar
trekker therefore totals
3000 kcal (for normal requirements) +
1500 kcal (for the cold) +
1500 kcal (for the extra effort), making a total of 6000
Kcal per day. |
In addition to this, nutritional amounts need to be adapted to
the physical and psychological capacity of the individual to eat
and digest food; given the fact that the two Belgians will be carrying
food for 100 days without any backup, everything needs to be put
in place to provide maximum nutrients with the minimum of weight.
Management of these problems means enormous modifications to the
normal balance of basic nutrients - in other words proteins, fats
and carbohydrates:
|
Proteins |
Fats |
Carbohydrates |
| Normal Percentage: |
8% |
33% |
26% |
| Expedition Percentage: |
12% |
66% |
55% |
Given that the percentage of protein drops, you might think that
the basic requirements are no longer being met; but in view of the
fact that the particularly high calorie levels involved, this equates
to a percentage of 94 g or even 126 g of protein per day. This is
equivalent to 1.3 g/kg of body weight rather than 1 g/kg normally
required.
Why eat more fats?
With one gram of fat generating 9 kCal instead of the 4 produced by
sugar, the weight/calorie ratio is excellent.
Fats supplied in large quantities will be laid down in the body's
tissues, first of all in between the organs and then under the skin.
These deposits are of vital importance for the body against the cold
and form a protective layer. With the permanent action of cold against
the body, a balanced spread of fat across the whole epidermis and
not just in the classic spots (stomach, buttocks, thighs) can be observed.
In fats, the poly-unsaturated acids, provide a barrier for the membranes
and reduce cellular dehydration. It is therefore vital to include
poly-unsaturates in polar rations to limit perspiration and excessive
evaporation, which poses serious problems such as the systematic freezing
over of clothes and sleeping bags.
The choice of fats for the expedition
During the expedition, requirements will vary from 50 g/day to 80g
/day, which gives us more or less the levels required. Despite the
high requirement for fats, the proportion of saturated fatty acids
and unsaturated remains balanced because foods have been selected
depending on their composition. Only those which are likely to provide
mainly "Cis-Cis" poly-unsaturates have been selected.
The choice of proteins for the expedition
The complementary nature of different sources of proteins is crucial:
proteins from the same group (cereals, animal origin, dried vegetables)
are deficient in one or more of the essential amino acids. Cereals
lack methionin, meats and vegetables lack lysin. To compensate for
this situation, the solution is to combine different protein sources
at mealtimes favouring the combination: cereals + vegetables or
cereals + animal proteins.
The choice of sugars for the expedition
Rapid-release sugars need to be avoided in favour of slow-release
sugars, so as to avoid pronounced glycaemic peaks after meals. On
the other hand, during the journey, provision of rapid-release sugars
can be tolerated because the cellular metabolism will be working
at full speed.
The choice of fibres for the expedition
These are contained in ground cereals, muesli and oleaginous fruits.
All the fibres provided are found in natural products and do not
disrupt the digestive organs.
Vitamins, mineral salts and trace elements
The choice of foods is made with regard to the calories supplied
by a relatively low volume, but equally depending on the natural
richness in vitamins, mineral salts and trace elements. Oils from
first pressings are very rich in fat soluble elements (A, D, E,
K) and the quantities chosen largely cover daily requirements. Cereals,
muesli, raw sugar and oleaginous fruits cover the requirements in
B vitamins, mineral salts (magnesium, potassium) and trace elements
(iron, copper, manganese, zinc, silicium, nickel, selenium). Cheese
provides the calcium requirements. While there is sufficient vitamin
C in the rations, it is still however necessary to add 2 g per day
because this will then compensate for any deficiencies by replacing
other vitamins.
Increasing calories during the expedition
In theory the expedition will last 100 days. The calorific rations
will progressively increase during the journey :
15 days at 4602 Kcal/day,
i.e. 12.150 kg
20 days at 5636 Kcal/day, i.e. 20.000 kg
65 days at 6206 Kcal/day, i.e. 70.200 kg |
Why not start off with 6000 kcal?
For the following reasons: - The body needs to get used to its new
diet - all surplus nutrients which have accumulated before the departure
are used up - during the first few days, you need to find your levels,
in physical effort and the daily tasks. The stress encountered by
this new way of life is anorexiagenic and takes away the will to
eat.
The division of meals
During the expedition, meals will be divided into 3 parts. Breakfast
represents 30% of the Total Energy Amount (TEA). It gives the body
the necessary energy in the first few hours of walking. The units
en route comprise 50% of the TEA. These are split into 9 to 10 blocks,
spaced out one per hour during the daily trek. The first is light
and gradually increases throughout the journey. Their frequency
allows the body to remain active throughout the effort whilst maintaining
a quasi-constant temperature. Furthermore as digestion takes place
over several hours, the body is able to absorb greater energy; this
leads to less tiredness for the organs. Dinner is light; 20% of
the TEA is eaten as soon as possible, so that digestion is completed
by the time the explorers go to sleep. Digestion produces a great
deal of heat and keeps the body warm during the evening rest in
the tent. If the meal is eaten just before bedtime, the production
of heat is excessive under the duvet causing the body to perspire
profusely,thus entailing problems of freezing on the surfaces.
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