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1.2. Known issues due to long stay at sea

Physiological


Lack of vitamin C : Scurvy

http://en.wikipedia.org/wiki/Scurvy

http://www.med.uc.edu/departme/cellbiol/Image7.gif
Scorbutic gums, a symptom of scurvy

Scurvy is a disease resulting from a deficiency of vitamin C, which is required for the synthesis of collagen in humans. The chemical name for vitamin C, ascorbic acid, is derived from the Latin name of scurvy, scorbutus. Scurvy leads to the formation of spots on the skin, spongy gums, and bleeding from the mucous membranes. The spots are most abundant on the thighs and legs, and a person with the ailment looks pale, feels depressed, and is partially immobilized. In advanced scurvy there are open, suppurating wounds and loss of teeth.
Scurvy was at one time common among sailors, pirates and others aboard ships at sea longer than perishable fruits and vegetables could be stored, and by soldiers similarly separated from these foods for extended periods. It was described by Hippocrates (c. 460 BC–c. 380 BC). Herbal cures for scurvy have been known in many native cultures since prehistory. In 1536, the French explorerJacques Cartier, exploring the St. Lawrence River, used the local natives' knowledge to save his men who were dying of scurvy. He boiled the needles of the arbor vitae tree (Eastern White Cedar) to make a tea that was later shown to contain 50 mg of vitamin C per 100 grams.[1][2] Such treatments were not available aboard ship, where the disease was most common. It was a Scottish surgeon in the British Royal Navy, James Lind who first proved it could be treated with citrus fruit in experiments he described in his 1753 book, A Treatise of the Scurvy.[3]
In infants, scurvy is sometimes referred to as Barlow's disease, named after Sir Thomas Barlow,[4] a British physician who described it. (N.B. Barlow's disease may also refer to mitral valve prolapse.) Other eponyms include Moeller's disease and Cheadle's disease.
Scurvy does not occur in most animals because they can synthesize their own vitamin C, but humans, other primates, guinea pigs, and a few other species lack an enzyme necessary for such synthesis and must obtain vitamin C through their diet. Vitamin C is widespread in plant tissues, with particularly high concentrations occurring in citrus fruits (oranges, lemons, limes, grapefruits); tomatoes, potatoes, cabbages, and green peppers.

So we envison the culture of these fruits in the floating gardens as our priority. We will privilege the species that have the best vitamin C ratio / tolerance to salty environment, movement, change of climate, mechanical resistance to the wind.



Mercury content

Main article: Mercury in fish

Fish and shellfish have a natural tendency to concentrate mercury in their bodies, often in the form of methylmercury, a highly toxic organic compound of mercury. Species of fish that are high on the food chain, such as shark, swordfish, king mackerel, albacore tuna, and tilefish contain higher concentrations of mercury than others. This is because mercury is stored in the muscle tissues of fish, and when a predatory fish eats another fish, it assumes the entire body burden of mercury in the consumed fish. Since fish are less efficient at depurating than accumulating methylmercury, fish-tissue concentrations increase over time. Thus species that are high on the food chain amass body burdens of mercury that can be ten times higher than the species they consume. This process is called biomagnification. The first occurrence of widespread mercury poisoning in humans occurred this way in Minamata, Japan, now called Minamata disease.




Lack of carbohydrates : Starvation

http://en.wikipedia.org/wiki/Nutrition_disorder

Carbohydrates are chemicals that can be broken down in the body to simple sugars like glucose, fructose. Glucose is primarily used by the body in muscles but is the primary energy source used by the brain. If an excess of carbohydrate is consumed then it is stored with a large quantity of water as glycogen in the skeletal muscles and the liver. Fructose cannot be used by the skeletal muscles, but is converted into glucose by the liver. However if large quantities of fructose are consumed, the conversion producestriglycerides which are thought not to be healthy. One major source of fructose is sucrose (table sugar), fruits also contain substantial quantities, and so should not be taken in excess.
The human body creates energy from chemical reactions (mainly oxidation) of food. Due to conservation of energy if more energy is absorbed from food, then weight gain occurs (in the form of glycogen and its associated water) and fat. Some variation in weight can also occur due to hydration levels.
Different components of the diet provide different number of net calories, roughly speaking proteins provide about 4.5 kCal, carbohydrates about 5 kCal and fats, 9.5 kCal per gram.
Research has showed that the idea of thin people having a 'fast metabolism' is false; human beings burn energy at quite predictable rates, and gain or loss of weight is mostly to do with calorie intake versus the bodies' basal metabolism (with people with more lean bodyweight burning more calories) as well as (usually to a lesser degree) activity levels; with any long-term excess being stored as fat.
Energy is also used for growth and repair.
The malnutrition associated with marasmus leads to extensive tissue and muscle wasting, as well as variable edema. Other common characteristics include dry skin, loose skin folds hanging over the glutei, axillae, etc. There is also drastic loss of adipose tissue from normal areas of fat deposits like buttocks and thighs. The afflicted are often fretful, irritable, and voraciously hungry.

How can we produce our own carbohydrates at sea?



Health benefit of eating seafood

http://en.wikipedia.org/wiki/Seafood#Health_benefits_of_eating_seafood

Research over the past few decades has shown that the nutrients and minerals in seafood can make improvements in brain development and reproduction and has highlighted the role for seafood in the functionality of the human body.[10]

Heart health
Doctors have known of strong links between fish and healthy hearts ever since they noticed that fish-eating Inuit populations in the Arctic had low levels of heart disease. One study has suggested that adding one portion of fish a week to your diet can cut your chances of suffering a heart attack by half.

Fish is thought to protect the heart because eating less saturated fat and more Omega-3 can help to lower the amount of cholesterol and triglycerides in the blood – two fats that, in excess, increase the risk of heart disease. Omega-3 fats also have natural built-in anti-oxidants, which are thought to stop the thickening and damaging of artery walls.

Regularly eating fish oils is also thought to reduce the risk of arrhythmia – irregular electrical activity in the heart which increases the risk of sudden heart attacks.[11]

Brain functionality
The human brain is almost 60% fat, and most of this is made of the Omega-3 fat DHA. Recent studies suggest that older people can boost their brain power by eating more oily fish, with those who enjoy it regularly are able to remember better and think faster than those who eat none. Other research has also suggested that adding more DHA to the diet of children with attention-deficit hyperactivity disorder can reduce their behavioural problems and improve their reading skills, while there have also been links suggested between DHA and better concentration. Separate studies have suggested that older people who eat fish at least once a week could also have a lower chance of developing dementia and Alzheimer's disease.[11]

Joint benefits
Including fish as a regular part of a balanced diet has been shown to help the symptoms of rheumatoid arthritis – a painful condition that causes joints to swell up, reducing strength and mobility. Studies also show that sufferers feel less stiff and sore in the morning if they keep their fish oil intake topped up.[12]

Recent research has also found a link between Omega-3 fats and a slowing down in the wearing of cartilage that leads to osteoarthritis, opening the door for more research into whether eating more fish could help prevent the disease.

Iodine, Selenium, Vitamin A, Zinc
Fish is high in minerals such as iodine and selenium, which keep the body running smoothly. Iodine is essential for the thyroid gland, which controls growth and metabolism, while selenium is used to make enzymes that protect cell walls from cancer-causing free radicals, and helps prevent DNA damage caused by radiation and some chemicals.

Fish is also an excellent source of vitamin A, which is needed for healthy skin and eyes, and vitamin D, which is needed to help the body absorb calcium to strengthen teeth and bones.




Excess of vitamin A : Hypervitaminosis_A

http://en.wikipedia.org/wiki/Hypervitaminosis_A

Hypervitaminosis A occurs when the maximum limit for liver stores of retinoids is exceeded. The excess vitamin A enters the circulation causing systemic toxicity. Betacarotene, a precursor of vitamin A, is selectively converted into retinoids, so it does not cause toxicity.
Signs of acute toxicity include nausea and vomiting, headache, dizziness, blurred vision, and loss of muscular coordination.

Effects include:
birth defects
liver
problems
reduced bone mineral density that may result in osteoporosis
coarse bone growths
skin discoloration
hair loss

excessive skin dryness/peeling (desquamation)
idiopathic intracranial hypertension



Psychological


Cabin fever





Bibliography


"Nutritional Aspects of Fish." Irish Sea Fisheries Board

"What's so healthy about seafood". Australian Government, Fisheries Research and Development Corporation.

Rice R. (2004)Seafood - an essential part of 21st century eating patterns. The Fish Foundation.

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