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Mars
Base Zero Nutrition |
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By Ray R. Collins
Note: references may not work until I finish linking my personal site with ISECCo's web site.
The Mars Base Zero diet is primarily limited by
calories. Both from the point of
producing enough for supporting a person, and from the point of having them in
a form concentrated enough so the consumer doesn't have to eat too much food in
one day. For example to obtain 3,000
k-calories from potatoes you would have to eat more than 6 pounds every
day! This is more than most people can
comfortably consume in a day.
To begin with, let us look at what we have available for
planting. The gross size of the
greenhouse is 24 ft by 36 ft, or 864 square feet. From this we need to subtract the chicken cage/compost heap (the
chicken cage is located over the compost), an area of 16 square feet. Our primary walkway is 8 inches wide and 24
feet long, for a total of 16 square feet.
(We also have side walkways, but we have pots on them, so they are
included in the available growing area.)
To get to the primary walkway we need some steps, probably 10. If each step is 2/3 of a square foot, this
is 6 square feet. The area with the
planting trays has a (limited) number of aisles down it; an E/W aisle, and a
N/S aisle. The E/W is 18 inches wide
and 12 feet long, and the N/S is 18 inches wide and 20 feet long. In addition there is another aisle in front
of the grow bench that is 18 inches wide and 8 feet long. These aisles total 60 square feet. So we are left with a total of 766 square
feet of growing area (864-16-16-6-60).
To develop the diet we approached determined that a minimum
of half the needed 3,100 k-calories (RDA for a person of my size) would be from
potatoes. Our productivity is estimated
at 0.75 pounds/sq ft/75 days, or 0.01
pound/sq/day. Since we will need
1550 k-calories, we will need 1550/495 k-cal (per pound of potato) = 3.1 pounds
per day of potatoes. This value is put
into the nutritional calculator. To produce
3.1 pounds per day of potatoes we will need 310 square feet planted in
potatoes. We are thus left with 456
square feet of growing area.
We know that we will be producing an egg a day. So we can add this to the nutritional
calculator. The chicken cage has
already been subtracted from the growing area.
We will be producing about 100 grams a day of strawberries,
so this too is added to the nutritional calculator. The majority of the strawberries are in hanging baskets, so they
take up little space. But we will need
a small amount of space, so subtract 15 square feet for the strawberries,
leaving 441 square feet of growing area.
At this point we should pause and examine what nutrients we
are missing. Although we only have 53%
of our k-calories, we have met 100% of our amino acid needs (due in large part
to the egg), though only about 60% of our bulk protein requirements. The most critical thing we are missing is
vitamin A, for we have only achieved 6% of the RDA.
Carrots are an excellent source of vitamin A, so we shall
plan for a carrot a day. To provide a
continuous supply of carrots at a carrot a day we will need to plant about 7
square feet, leaving 434 square feet of growing area. The next lowest dietary item is calcium. Doing a search on calcium (limited to what
we can produce in our ecosystem) we discover that spinach, soybeans, turnip
greens and white beans are all good sources.
Spinach is the highest, so we want to eat a cup of spinach a day. Though we lack specific growth data on
spinach we estimate that 12 square feet will be needed, leaving us with 422.
We still have only achieved 35% of the calcium we need, but
selenium is now the lowest at only 20% of RDA.
Whole wheat is an excellent source of selenium (and good for adding
calories to the diet), so we shall add in a cup of whole wheat flour. To make a cup of flour we will need about
2/3 cup of wheat berries which weigh about 4.25 ounces. Using our field data
we estimate we will need to harvest about 3.5 square feet of wheat every day
(we assume we will achieve our best field yields). Since wheat takes about 60 days to mature, we will need to have
210 square feet devoted to wheat. We
are now left with 212 square feet.
What nutrients are we lacking now? Here is a short table:
Nutrient |
% RDA |
B12 |
26 |
Calcium |
38 |
Vitamin E |
50 |
Sodium |
62 |
Zinc |
64 |
Calories |
69 |
Riboflavin |
83 |
Protein |
92 |
Vitamin B-12 is a real problem, so we will examine that
later. Sunflower seeds are a good
source of vitamin E, calories and also has zinc in it. We would like to eat an average of 1.3
ounces of sunflower seeds per day.
Currently we are using about a tablespoon per day in oil for cooking
(grease pans, add to bread, etc). Since
there are 2 of us, this equals 1/2 tablespoon per day per person. To produce this we will need about 2.7
ounces of sunflower seeds (Duhon
1985) per day. To produce our 4
ounces per day of sunflower seeds we will need to plant 157 square feet in
sunflowers (calculated from information presented in Jeavons
1995, page 84--assumes maximum yield) {ouch!}. This leaves us with only 55 square feet of garden space.
Calcium is still very low (43% of RDA). Sodium is also low at 63% of RDA. Turnips are an excellent food source for us,
for they are high yielding and the greens one of the higher vegetables in
calcium. So we will devote 30 square
feet to turnips, which we estimate (from our garden data)
is capable of producing 2.4 pounds per square foot in 60 days, or an average of
1 pound per day of root plus a cup a day in leaves (we slightly reduced the
root productivity due to harvesting the leaves). We are now left with 25 square feet of garden space (calculated
from information presented in Jeavons
1995, page 88--assumes maximum yield).
Peanuts are a very versatile crop. We shall aim to provide 1 ounce per day. This will likely require the last of our
garden space .
We do have another food source, to help fill in the missing
vitamins and minerals. We will be
raising chickens. Very few will be to
eat, they are primarily used for egg production. However we expect to be able to eat about 1 chicken per
month. One of the highest sources
available to us for vitamin B12 is chicken liver. One serving of liver has enough vitamin B12 for 12 days! So we shall add 1/10th serving per day of
chicken liver. We now have enough
vitamin B12, but are still short on calcium and sodium. The chicken will also add 1/3 serving of
chicken (one ounce) per day.
So, where are we at?
All of the garden space has been used, but we are still short on a few
nutrients. A complete nutritional
analysis of the above diet:
Nutrient |
Amount |
Measured In |
%RDA |
Mono. Fat |
13 |
Gm |
30 |
Saturated Fat |
7 |
Gm |
51 |
Calcium |
777.5 |
Mg |
61 |
Total Fat |
44 |
Gm |
64 |
Carbohydrate |
488 |
Gm |
82 |
Calories |
2615 |
Cal |
84 |
Sodium |
452 |
Mg |
85 |
Zinc |
14 |
Mg |
89 |
Riboflavin |
2 |
Mg |
113 |
Protein |
92 |
Gm |
136 |
Phosphorus |
1991 |
Mg |
155 |
Vitamin B12 |
3.3 |
Mcg |
157 |
Selenium |
122 |
Mcg |
163 |
Poly. Fat |
20 |
Gm |
191 |
Fiber |
63 |
Gm |
210 |
Niacin |
43 |
Mg |
212 |
Thiamine |
3.5 |
Mg |
218 |
Magnesium |
957 |
Mg |
256 |
Vitamin E |
29.3 |
Mg |
274 |
Pant. Acid |
15 |
Mg |
281 |
Copper |
6.6 |
Mg |
310 |
Cholesterol |
324 |
Mg |
324 |
Vitamin B6 |
6.9 |
Mg |
324 |
Tyrosine |
3.2 |
Gm |
333 |
Iron |
38 |
Mg |
358 |
Manganese |
12 |
Mg |
368 |
Potassium |
8663 |
Mg |
405 |
Phenylalanine |
4.3 |
Gm |
444 |
Folacin |
961.17 |
Mcg |
449 |
Cystine |
1.4 |
Gm |
483 |
Isoleucine |
4 |
Gm |
556 |
Methionine |
1.7 |
Gm |
567 |
Valine |
4.9 |
Gm |
581 |
Vitamin C |
321.7 |
Mg |
601 |
Leucine |
6.3 |
Gm |
655 |
Lysine |
5 |
Gm |
693 |
Threonine |
3.4 |
Gm |
719 |
Tryptophan |
1.3 |
Gm |
727 |
Vitamin A |
45537 |
IU |
851 |
Low fats are not a problem; we can ignore them. The low calcium may not be a serious
problem; in people in China who are on a diet that is primarily vegetarian eat
only half as much calcium (with no deficiency symptoms) as the US RDA (Walford
and Walford, 1994). This may be due
to improved absorption of calcium; on average adults absorb about 30% of the
calcium they ingest (Whiney
and Rolfes, 1993). Whiney and Rolfes
also state that "The ideal calcium intake for people is difficult to
determine…[because] its blood concentration does not reflect calcium
status. Calcium recommendations are
therefore arrived at by way of balance studies." These balance studies give different results depending on who
does them, and around the world there is wide variation on recommended daily
allowances. For instance, the RDA for
the US is 1300 milligrams, and the world Health Organization (WHO) recommends
only 400-500 milligrams/day. Therefore,
though lower than the US recommendations, we are above the WHO recommendation
so we shall accept our low calcium, though a careful watch on bone density is
desired (note: in relation to my non-biosphere diet, my calcium intake actually
increases).
Zinc is very poorly absorbed, with 60 to 85 percent of that
consumed passing through and being eliminated.
Fiber inhibits zinc absorption; this may be a problem since the diet is
very high in fiber. In setting the zinc
RDA, they assume only 20% are absorbed.
This may actually reflect a value that is lower than we need due to the
large quantity of fiber in the diet.
However we may be able to supplement simply by increasing the amount of
zinc in the soil, for vegetables vary in zinc content depending on the zinc
content of the soil they were grown in.
So, based on this, the addition of a small amount of zinc to the soil of
a biosphere is recommended, as is watching for deficiency problems. These symptoms include blood: high
ammonia, low alkaline phosphatase, low insulin; bones: growth retardations,
abnormal collagen synthesis; cells/metabolism: slow DNA synthesis,
impaired cell division and protein synthesis; digestive system: weak
sense of smell, poor sensitivity to the taste of salt, weight loss, delayed
glucose absorption, diarrhea, nausea, impaired folate absorption; eyes:
night blindness; glandular system: delayed onset of puberty, small
gonads in males, decreased synthesis and release of testosterone, abnormal
glucose tolerance, reduced synthesis of adrenocortical hormones, altered
thyroid function; immune system: altered skin test responses, low white
blood cell count, few anti-body forming cells, thymus atrophy, susceptibility
to infection; liver/spleen: enlargement; nervous/muscular systems:
anorexia (poor appetite), mental lethargy, irritability; reproductive system:
low sperm counts; skin: generalized hair loss; lesions; rough, dry
appearance, slow healing of wounds and burns (Whiney
and Rolfes, 1993). Should any of
these symptoms appear a doctor's visit is needed. To prevent deficiency supplements may be needed.
Sodium has no specific RDA, mostly because diets are so
rarely lacking in it. The Committee on
Dietary Allowances estimates the minimum sodium requirements for adults to be
500 milligrams. This estimate is only
slightly higher than the amount in our diet.
By using blood products from the chickens it should be easy to boost the
diet to the minimum estimated RDA.
This has been a first pass through the possibilities. A number of important foods were left out;
further analysis should include them.
For example soybeans, brassicas, parsnips, onions, etc. A second pass will be done at a later date;
we know that we will need to plant the initial garden and can proceed at a
later date with refining the nutrient and plant balance.
We shall now make a second attempt to design a diet that
maximizes nutrition (including calories) while minimizing garden space.
Parsnips are the most area efficient vegetable you can grow
(Duhon
1985). So let us start with 1
serving per day of parsnips (1/2 cup or 67 grams--1.5 pounds). To grow half a cup per day we will need
Food |
Area Needed to grow food |
Pounds produced per day (goal) |
Remaining garden area (766 square feet minus area needed) |
Calories per day in the food |
Calories left to consume (3100-calories) |
Info sources |
Potato |
200 |
2 |
566 |
990 |
2200 |
|
Parsnip |
10 |
1/3 pound |
556 |
100 |
2100 |
|
Egg |
0 |
1 egg |
556 |
77 |
2023 |
|
Strawberries |
15 |
1/4 pound |
541 |
30 |
1993 |
|
Carrots |
7 |
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Soybeans are a versatile food that is high in calcium. Add 1 cup of soybeans per day, which gets us
to 93% of RDA for calcium, and 98% RDA for sodium. To get our 1 cup per day we will need 336 square feet (calculated
from information presented in Jeavons
1995, page 88--assumes maximum yield) continuously planted in soybeans
{ouch!}.
Brassicas are excellent vegetables. For variety we should include a number of
them in our diet. About 1/4 serving per
day of broccoli, cabbage, cauliflower and kohlrabi. 8 square feet should be sufficient to provide a continuous supply
of these (calculated from information presented in Jeavons
1995, page 80--assumes medium yield).
Parsnips are the most area efficient vegetable you can grow
(Duhon
1985). So let us add 1/2 serving
per day of parsnips (1/4 cup).
Onions are another very efficient crop you can grow (Duhon 1985). One serving per day (1/2 cup).