Proteins are one of the basic building blocks of your organism. They are often compared to the bricks used to construct a house, with one important difference: proteins are constantly being used up and have to be replaced regularly. Eating foods that contain protein is therefore a vital necessity. If you don’t, your cells will not be able to grow or regenerate.
The process of cellular regeneration is visible to the naked eye: every day some of your hair falls out and new hair grows in; the outer layer of your skin flakes off and is replaced by new skin. The same thing happens to the cells inside your body, so it is essential that they be provided with the building blocks they need to regenerate.
Proteins are also one of the elements comprising nucleic acids, which are essential for human reproductive functions, and are the basic components of enzymes, especially those involved in digestion.
So you can see just how important proteins are for maintaining internal bodily functions.
Where to get your protein
Large amounts of protein are contained in:
– fish, seafood and shellfish
– dairy products
Substantial amounts are also found in:
– seeds and nuts (walnuts, hazelnuts, almonds, pine nuts, pistachio, peanuts, etc.)
– beans (white beans, peas, kidney or Lima beans, lentils, soybean)
Many other foods contain protein, but in smaller amounts:
– grains and their derivative products (whole grain bread, pasta, rice, etc.)
– green vegetables
Amino acids: a crucial role
During digestion, proteins may be broken down into simpler substances called amino acids. The transformation begins in the stomach, and continues in the small and large intestines.
Amino acids produced by this chemical process can pass through intestinal walls, to be absorbed by blood and lymph, which transports them to your cells.
Using amino acids, each cell then recomposes living proteins, the structure and composition of which are particular to the organ or tissue of which the cell is part.
The food you eat must provide you with 8 essential amino acids, because your body is not capable of synthesizing them on its own. They include:
Getting all 8 amino acids is doubly important for the following reason: if only one is missing, the others may be assimilated badly, or not at all.
Most foods, except eggs, do not contain all 8 essential amino acids. They may contain one or even a few, but the absence of the others (or their presence in overly small amounts) can inhibit the assimilation of the amino acids they do contain.
Meat and cow’s milk, for example, lack methionin ; fish lacks tryptophane. This means that the only way to provide your body with all essential nutrients in precisely the right amounts is to eat a BALANCED and varied diet.
With this in mind, you can understand how extraordinarily important is it to keep your diet balanced if you want to stay healthy – or get healthier.
We now know, for example, that a lack of the amino acid tryptophane has an adverse effect on sleep. If you sleep badly and eat mainly fish, and very little meat and/or dairy products (this kind if diet is becoming more and more common, especially among persons who want to lose weight), then you can see how changing your diet to include more tryptophane-rich foods can solve your sleep problem.
You can also understand how, at certain times your body may need more of certain amino acids because your cells have to regenerate faster. This is true of children, pregnant or breastfeeding women, and persons who are fighting a disease or convalescing.
How much do you need per day?
Proteins should constitute 15% of your daily food intake. The amount generally recommended is 1 gram of protein per kilogram of body weight . Thus a man weighing 80 kilograms (about 175 pounds) would need about 80 grams (3.5 ounces) of protein per day, while a woman weighing 60 kilograms (about 130 pounds) would need about 60 grams (2.2 ounces) a day.
Growing adolescents and persons who do a lot of sports or demanding physical work can increase their protein intake to 1.5 or even 2 grams per kilogram of body weight.
To give you some idea of how this translates into actual food, you should know that 100 grams of meat contains between 15 and 20 grams of protein, as do:
– 100 grams offish
– 2 eggs
– half a litre of milk
– 60 grams of gruyere type cheese
However, as we mentioned earlier, vegetables, grains, nuts and algae also contain proteins. Scientists refer to them as vegetal proteins. Although they are easy to assimilate, they do not have the same biological value as protein obtained from non-vegetal sources, primarily because they lack one or a number of essential amino acids.
For example, vegetal proteins obtained from grains generally lack isoleucine and lysine. On the other hand, it’s easy to compensate for this lack by combining a grain with another source of vegetal protein (in the same meal). Eating a grain like rice with a feculent vegetable (beans, lentils, peas, soybean, etc.) provides you with all 8 essential amino acids. You could also combine a grain with a meat or dairy product (cheese, eggs, chicken, etc.).
The minimum daily protein requirement for a woman weighing 60 kilograms (130 pounds) is about 44 grams (1.6 ounces). This can be obtained by eating one portion of lean meat, poultry or fish (providing 20 grams of protein), a slice of medium cheese (8 grams of protein) one egg (6 grams of protein), a slice of whole grain bread (2 grams of protein) and drinking a cup of milk (9 grams of protein).
That adds up to 45 grams of pure protein, which is sufficient for a woman engaged in normal day-to-day activities. The rest of her diet could be composed of vegetables (especially green vegetables) and fruit. Meat, poultry and fish could also be replaced on occasion by a grain, combined with an appropriate legume like Lima beans, black beans, lentils, etc.
A century ago people consumed three times more vegetal protein than meat. Today the proportions are exactly the opposite.
The most recent studies have shown that the ideal ratio is 50% animal protein and 50% vegetal protein. For that reason it is urgent that people change their eating habits, adding more feculent vegetables (beans, lentils, soybean, etc.) and unrefined grains (whole grain bread, whole grain rice, etc.) to their diet.
But remember, there is no need to go to extremes. Whole grain rice and wheat flour lack lysine; corn flour lacks tryptophane and lysine; beans lack cystine and methionin; soybean, peas and peanuts lack methionin, and so on. We repeat – the only way to get all the essential nutrients you need is to keep your diet varied and balanced.
Table: Sources of vegetal protein (per 100 grams)
Almonds: 19 grams
Roasted peanuts: 25 grams
Whole wheat: 12 grams
Powdered cocoa: 17 grams
Chestnuts: 8 grams
Dark chocolate: 6 grams
Oat flakes: 14 grams
Wheat germ: 26 grams
Soya beans: 35 grams
Cooked white beans : 8 grams
Sprouted white beans: 21 grams
Cooked red beans: 8 grams
Cooked lentils: 8 grams
Corn: 9 grams
Canned corn: 2.5 grams
Popcorn: 3.5 grams
Walnuts: 10 grams
Barley: 11 grams
Nettle soup: 8 grams
White bread: 2.5 grams
Whole grain bread: 9 grams
White pasta: 3 grams
Whole wheat pasta: 8.5 grams
Cooked chick peas: 8 grams
Cooked potatoes: 2 grams
Whole grain rice: 2.5 grams
Rye: 13 grams
Semolina: 5 grams
Spirulina (algae): 25 grams
Carnitine: a unique substance
Among substances derived from the 8 basic amino acids, carnitine merits special consideration, since it plays a unique role in maintaining your organic functions.
Carnitine is synthesized in your liver and kidneys. It is then transported via the blood to your cells, and especially to muscle cells, which contain up to 40 times more carnitine than other cells in your body. Its primary role consists of promoting better combustion of fats to produce energy.
Without carnitine your muscles cannot burn fat. This results in muscular fatigue, a general lack of energy, extreme sensitivity to cold, and weight gain caused by the accumulation of fat in your body.
What happens if you develop a protein deficiency?
A lack of protein-rich foods in your diet can, over time, cause the following symptoms:
– Weight loss: unfortunately you gradually start losing muscle mass, not excess weight. That’s why diets consisting solely of fruits and vegetables may seem to be effective at first, but are actually dangerous for your health. Why? Because the gradual deterioration caused by this kind of diet affects all the muscles in your body – including your heart! A number of cases have been reported of women embarking on a strict diet without medical supervision, who have actually suffered heart attacks. Our advice: never play sorcerer’s apprentice where your health is concerned. Eliminating one or a number of essential foods from your diet without understanding the consequences can be dangerous!
– Fatigue or asthenia: your organism suffers from general weakness.
– Digestive problems: as we said earlier, amino acids play an essential role in the production of gastric juices.
– Concentration and memory problems: brain cells need amino acids to grow and survive. Proof lies in the unfortunate fact that if fetuses or mothers suffer from malnutrition during the first few months of pregnancy, children are often born with some degree of irreversible mental retardation.
Effects on the elderly
As people get older, their ability to synthesize proteins diminishes. This means they need to absorb more proteins in order to prevent a deficiency. Elderly persons should actually multiply the average minimum daily intake by 2.
At the same time, it seems that many people eat less and less meat the older they get, for a variety of reasons: tastes change, so that many aging people simply no longer enjoy the taste of meat; loss of teeth makes chewing meat more difficult; reduced income makes meat, which is relatively expensive, less accessible, and so on.
Many older persons who live alone or who suffer from mild depression tend to lose interest in cooking, increasing their risk of developing a protein deficiency. This, in turn, weakens their immune system, making them more vulnerable to infection and disease.
Studies have shown that elderly persons are three times more likely to develop infections. As you may know, even common infections like the flu or a cold can become serious, or even fatal, when the immune system is weak.
Once again the medical establishment seems not to fully understand the essential role played by nutrition in maintaining health and preventing disease. Statistics have shown that over 50% of elderly persons living in nursing homes, and 70% of those in hospitals, are protein deficient! Older persons who live at home are much less likely to develop a protein deficiency, probably because they enjoy their own cooking, and instinctively seek out the nutrients they need.
Until recently, the recommended daily protein intake for elderly persons was based on the same calculations as those for young adults, I.e. about 0.6 grams per kilogram of body weight. Radioisotope technology has helped scientists become much more precise in measuring protein metabolism. It was found that older organisms use amino acids less effectively to break down calories. It is therefore recommended that older persons increase their daily protein intake to about 1 gram per kilogram of body weight.
Two additional factors should be taken into consideration:
– Older persons who contract an infection should increase their protein intake. In fact, any kind of physical stress (increasingly common in aging organisms) tends to alter gastrointestinal functions, which in turn inhibits the proper use of digestive proteins.
– 1 gram per kilogram of body weight is the minimum and not the optimum requirement for ensuring continued health and longevity. Testing immune cells seems to be a promising method for determining optimum requirements. Two researchers, Dillon and Derby, produced significant improvements in cellular immunity simply by supplementing elderly subjects’ diet with 15 grams of milk per day. In future, lymphocyte reactions may become a reliable indicator of the protein status of aging organisms, and serve as a way of quantifying optimum requirements.
Sources of protein
Meat, one of the main sources of protein, also provides the body with iron, some vitamins (notably B-complex vitamins) and an essential fatty acid (arachidonic acid).
Although older persons should eat meat regularly, they don’t have to serve it with every meal. Other good sources of animal protein include fish, eggs and dairy products. These proteins have the same nutritional value as those obtained from meat, and are generally less costly.
Vegetal proteins obtained from grains and dried vegetables are also helpful, although their nutritional value is not as high. To get the most out of vegetal proteins, grains and dried vegetables should be combined in the same meal, or combined with a source of animal protein.
One gram of dairy protein costs about the same as a gram of protein obtained from eggs. A gram of meat protein, however, is about three times more expensive, and a gram of fish protein about two and a half times more expensive (except for sardines).
Too much animal protein and too little vegetal protein
The situation is extremely common these days – both men and women tend to eat meat twice a day, and at the same time almost entirely ignore vegetal sources of protein.
Eating too much meat, fish, eggs and cheese causes excess toxins (notably purines and uric acid) to accumulate in your blood, and subsequently in your cells. This places a strain on some of your organs: as your liver and kidneys try to eliminate large amounts of toxins they become fatigued, and eventually start to degenerate; blood and cells gradually become poisoned as organs of elimination no longer function properly. In time the entire body becomes clogged and threatened by disease.
Initial discomfort worsens over time, often resulting in:
– kidney problems
– liver problems
– heart disease
It’s easy to see how reducing your intake of animal proteins can have a highly beneficial effect on your liver and kidneys. Nutrition plays a crucial role in keeping both these organs – and your entire body – healthy. A balanced diet is all you need to prevent such problems from occurring.
In addition, according to some epidemiological studies, eating too much meat increases your risk of developing colon cancer.