Title: EAT FISH, LIVE BETTER Prof. Thomas T. George Global Aquaculture Consultants
Author: Thomas T. George
Date: 02-18-2014, 04:40 AM
EAT FISH, LIVE BETTER
Prof. Thomas T. George
Global Aquaculture Consultants.
Physicians and dietitians regularly suggest fish for healthy eating at least twice a week because of their exceptional nutritional value. Wild and farmed fish have the same nutritional value and both are superior to beef, pork, and chicken. Fish meat is one of the best sources of high-quality protein, vitamins, minerals and omega-3 fatty acids which are extremely important for human health.
Fish protein is made up of long-chains of small subunits called amino acids and that is why fish meat, unlike meats of other animals, contains the essential amino acids which cannot be manufactured by the human body but must be ingested in the diet, namely: Arginine, Histidine, Lysine, Leucin, Isoleucine, Valine, Methionine, Phenylalnine, Threonine, and Tryptophan. It occurs between 20-30% of the fish dry weight and its percentage in every 100 grams is 19.5% as compared to 16.5% for beef, 13.6% for eggs, and 3.9% for milk. Besides, fish protein is low-fat and easier to digest than that of other meats because fish meat has very little connective tissue and shorter muscle fibers. It is a more efficient source of energy for human body than carbohydrates which are made of sugar, starch and fibers that are derived primarily from fruits, vegetables and grains. Burning one gram of fish protein produces nine calories of energy whereas that of carbohydrates produces only five. However, protein is not what the human body needs to burn for energy because when it is burned, toxins are produced which during elimination, put stress on the body and could result in fat storage and lean muscle. Therefore, to maintain healthy muscle and organ function throughout the day and during physical activity, sufficient amounts of complex carbohydrates derived from whole grain must be consumed to prevent the body using protein for energy because they are excellent source of fuel for the muscle and brain when broken by the body into simple sugars and burned.
Vitamins fall into two categories: fat-soluble and water-soluble. The fat-soluble vitamins A, D, E, and K, dissolve in fat and can be stored in the human body. The water-soluble vitamins – C and the B complex vitamins (such as B6, B12, niacin, riboflavin and thiamine) need to dissolve in water before the body can absorb them. Because of this, the body cannot store these vitamins and any of them that the body does not use as it passes through the system, gets rid off through urination. So, the body needs fresh supply every day. Whereas, vitamins are organic substances, minerals such as calcium, magnesium, iron, copper, phosphorous, selenium and iodine are inorganic elements that come from the soil and water and are absorbed by plants or eaten by animals. The body needs larger amounts of some minerals, such as calcium, to grow and stay healthy. Other minerals like iodine, iron, and selenium are called trace elements because the body needs very small amounts of them every day. Vitamins and minerals boost the immune system; support normal growth and development, and help cells and organs do their jobs. Moreover, the fats of fish (about 25% of body weight) are unsaturated fatty acids that lower blood cholesterol level and triglycerides (fats) in human body and reduce incidence of cardiovascular disease while that of other meats are saturated fatty acids which raise blood cholesterol and cause heart problems.
Cholesterol is a soft, waxy substance found among the lipids (fats) in the human blood stream and all the body’s cells. About 80% is produced naturally by the liver (approximately 1,000 mg per day) while only 20% is produced by diets of animal origin (e.g. meats, diary foods, and egg yolks). When dietary cholesterol is decreased, the liver compensates by producing more cholesterol. The recommended daily intake of cholesterol for an adult is 300 mg.
Despite the negative connotations associated with cholesterol, it is an important structural component of all cell membranes, extremely necessary to build and repair cells, produce steroid hormones, bile acids for digestion of fats and absorption of fat soluble vitamins A, D, E and K; and also, is the main precursor of vitamin D in the skin. It does not dissolve in the blood and has to be transported to and from the cells by special carriers called lipoproteins, the low-density lipoprotein (LDL) or “bad cholesterol) that carry cholesterol from the liver to the cells and the high-density lipoprotein (HDL) or “good” cholesterol which takes about one-third to one-fourth cholesterol from the cells back to the liver for break down and elimination from the body. About two thirds of the total blood cholesterol is in the form of LDL and even though it is called “bad” cholesterol, the human body needs a normal amount of it for cell growth and repair. But, when these lipoproteins go out of balance in the bloodstream (LDL more than HDL), the excess lipids cannot be removed efficiently and start the build up of “plaque” on the walls of arteries that make them stiff, brittle, narrow and prevent the heart from getting enough blood. This condition is known as atherosclerosis which ultimately causes heart attack or stroke. Therefore, blood cholesterol levels below 5.2mmol/L (200mg/dL) are desirable and those over 6.2mmol/L (240mg/dL) are classified as high cholesterol. High HDL levels protect against cardiovascular disease while low level (less than 40 mg per dL in men and 50 mg per dL in women) may raise stroke risk. However, because intake of dietary fibers such as fruits, vegetables, grains, nuts, and seeds, lower levels of “bad” cholesterol (LDL) by speeding up its breakdown in the liver, it is extremely important to eat fish with dietary fibers. Also, updated scientific analysis corrected the unfair reputation about shellfish (molluscs such as oysters and crustaceans such as shrimp) as raising cholesterol levels. A study at Rockefeller University Hospital, co-sponsored by Harvard School of Public Health, confirmed in 1996 that cholesterol level in shrimp diet raises levels of HDL, or “good cholesterol”, and decreases levels of LDL, or “bad cholesterol”. Besides, shrimps are low in calories, total fat, saturated fat, and, as fish, are good sources of omega-3 fatty acids.
Omega-3’s are long-chain polyunsaturated fatty acids (n-3 PUFA) which include: the short-chain alpha-linolenic acid (ALA, C18:3 n-3) and the long-chain eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3). ALA is found normally in vegetable oils, particularly flaxseed, soy and canola oils, and nuts such as walnuts; small amounts are found in green leafy vegetables. Fish is the major source of EPA and DHA, particularly fatty fish such as salmon, trout, tuna, mackerel, herring, sardines and also, shellfish or fish oils; they are totally absent from plant sources. The quantity of EPA + DHA in fish is highly dependent on the species, and to a lesser extent on environmental variables, packaging and cooking methods. EPA + DHA can also be synthesized in the body from ALA. About 8-30% of the daily ALA intake can be converted to EPA + DHA combined; however, most ALA is oxidized as a source of energy. The majority of fish oil supplements and concentrates of EPA + DHA extracted from fish are essentially free from environmental contaminants such as mercury, organochlorines and PCBs. Two servings of fatty fish per week correspond roughly to a daily intake of about 0.5g of EPA + DHA.
The Institute of Medicine states that ALA is not known to have any specific functions other than as a precursor to EPA and DHA. Now, it has been scientifically proven that EPA +DHA are scientifically vital for human health from the cradle to the rocker. The American Heart Association (AHA) in its 2003 recommendation stated that 2g-4g of EPA + DHA taken daily can lower triglycerides by 20% to 40%. Human breast milk contains both DHA and EPA in a 4:1 ratio, indicating the importance of both nutrients in infant nutrition. DHA, in particular, is most important for the development of human brain and retina of the eye. It is essential because fats make up more than 60% of the human brain and nervous system, and a considerable part of that is DHA; it is incorporated into the brain during fetal development and the first two years of life. Besides, omega-3’s make blood clotting more difficult, improve heart beats and prevent the build up of “plaque” on walls of arteries (atherosclerosis) which cause heart attack and stroke. Also, they reduce: heart disease by lowering blood fats and pressure; levels of blood sugar and damage to kidney that occurs in some insulin-dependent diabetics; the development of Alzheimer’s disease in senior citizens; certain inflammatory diseases such as arthritis, and psoriasis; risk of some types of cancer (colon cancer); and various forms of depression.
Eating dietary fiber, fresh fish and shellfish, therefore, is extremely important for human health; fish and shellfish lose their nutritional value if they are not chilled immediately after being caught or eaten fresh. Previously, there has been advice from food standards bodies to pregnant and breast-feeding women to limit their intake of fish/seafood because of mercury contamination. Now, based on the outcome of the last two World Seafood Congresses (Sydney2005 and Duplin 2007), the US Food and Drug Administration (FDA) urged the US Federal Government and all Public Health Authorities around the world to encourage pregnant and nursing women and young children to eat safely up to 12 ounces of most fish/seafood a week due to growing evidence that fish consumption can reduce the risk of coronary heart disease and can benefit neurodevelopment in the fetus and young children, taken into consideration that half of the fish consumed as food worldwide, are from aquaculture and mercury had never been an issue with farmed fish. More precisely, the Food and Nutrition Board of the Institute of Medicine (National Academy of Sciences, U.S.A.) recommends the following daily allowances of DHA and EPA per day: 70 mg, 90 mg, 110/120 mg, and 110/160 mg for children 1-3 years, 4-8 years, 9-13 years and 14-18 years respectively; 160 mg for adult men; 110 mg for adult women; 140 mg during pregnancy. Furthermore, according to a new research published in the Journal of the American Heart Association by scientists in Ireland, eating fish may help to reverse some of the damage (hardening of arteries) caused by smoking cigarettes. So, EAT FISH, LIVE BETTER!