Currently there is a lot of talk about protein.Protein is essential for life. It provides the building blocks for all cells and membranes, hormones and various growth factors. Protein is found literally everywhere in your system: there is protein in your muscle tissues, your heart, in the enzymes that digest your food, in your skin cells and even within your blood.
It shouldn’t surprise you to learn that most of us eat more protein than necessary to maintain life — 50 to 70 grams per day, which is about what you would find in a large steak. The difficult part is choosing the healthiest protein sources. Even if you’re a vegetarian who lives on bread, cereals, nuts and beans, you should still meet the minimal amount of complete protein requirements as long as you eat enough food in general. Yes, plant sources have limiting amino acids (grains are deficient in lysine and tryptophan; legumes and beans don’t have enough methionine), but you can overcome the disadvantage simply by eating more of the protein in question from a particular food. The important point is that you fix the shortage on the same day — preferably as part of the same meal.
Dairy and eggs are some of the best sources of protein. Eggs have the highest digestibility score and are ranked as the ‘gold standard’ of all proteins. Milk proteins, casein and whey, are comparatively excellent. The best-selling protein shakes are all based on milk proteins.
Protein sources: food vs supplements
You may be wondering if it makes any difference if you eat your protein from a supplement or from food.
Before we explore the undercover story of the amino acid sources, I need to mention one thing: I am not going to start a campaign against multi-million dollar industry of supplements, of course. There are a lot of good supplements on the market, and I’ve used many of them. In fact, I take all sorts of man-made lab-produced stuff and spend a hefty chunk of my salary on vitamins, minerals, individual amino acids and essential fats, digestive enzymes and, of course, meal replacement shakes and bars. Do they ‘work’? Of course they do! They provide me with the nutrients I expect.
Does cooking destroy proteins?
Somewhere between one and two million years ago, ancestors of humans began to cook food. They found it tastier than raw food, easier to digest and better for them: they were less likely to die of food poisoning because cooking killed any bacteria in the food.
Today most of the food we eat is cooked. Little attention is given to the effects of cooking and processing upon the amino acids in foods. We take for granted that a dish containing meat will contain all of its basic constituents. However, the processes of heating and preserving change the chemistry of whole foods.
Raw foodist Dr Bernarr, author of Why All Should Eat Only Raw Foods Always, has stated that heating food above 118° Celsius destroys all of the enzymes, 50 per cent of the protein, 50 per cent of vitamins, and 80 per cent of minerals. Next question: So what? Does it really matter to your overall protein intake? Let’s find out.
There are some people who eat only raw food, believing that cooking alters the natural integrity of the food. So-called ‘raw foodists’ eat few if any animal products and won’t heat any food above 40° Celsius.
One important raw food enthusiast was Armand Tanny who refused to cook his food after a visit to the Hawaiian islands in 1947. Originally a weightlifter with strength you can only wish for, Armand got all his protein from the same foods you do, but he ate them raw. His diet included tuna, beef, liver, lobster, oysters, clams, nuts, seeds, fruits and vegetables. We don’t know whether it was his genes or training, but Armand credited his 1950 Mr USA and Pro Mr America titles to his raw-food diet.
Even today there are plenty of health and fitness gurus who may not be so brave with raw meats, but they would not touch an egg if it is cooked.
Some bodybuilders follow the raw-egg path, and prefer protein shakes and bars to cooked fish, meat and poultry, believing the process of cooking any food destroys the very goodness of the product and will not provide sufficient nutrients their growing protein-deficient bodies so desperately need.
To bring you up to date and upgrade your knowledge about exposing eggs or other amino-sources to heat we need to verify what heat does to the food and whether cooking renders protein indigestible. The dilemma is not whether cooking destroys the enzymes, but what the effects of heat are in breaking down vitamins, amino acids and producing cross-linkages in starches, sugars fats and proteins.
Individual protein molecules in raw meat, fish, milk or eggs are wound in coils, which are formed and held together by bonds. When cooked or agitated (as occurs when egg whites are beaten), proteins undergo physical changes called denaturation and coagulation.
Denaturation is a modification of the molecular structure of protein. This can happen in a number of ways: heat, acid, alkali or ultraviolet radiation that destroys or diminishes the protein’s original properties and biological activity. The most significant effect of protein denaturation is the loss of its biological function. For example, enzymes lose their catalytic powers and haemoglobin loses its capacity to carry oxygen. Coagulation simply means the process by which something changes from a fluid into a thickened mass. In case of protein coagulation, the peptide bonds are broken causing the amino acid chains to unravel, which is an important process in the human body, causing the blood to clot.
However, while the changes that accompany denaturation and coagulation can have detrimental effects on the human body, saying that cooking destroys dietary protein and makes it useless is part of the nonsense promulgated by mainstream hippies and raw-foodists. Unless you cook yourself in the microwave, the ‘protein denaturation and coagulation’ is actually a good thing — it makes the food safe to eat by killing bacteria so you don’t die after eating a contaminated product.
Cooking and human digestion are virtually the same: both de-nature proteins, as well as other nutrients, and make it easier to absorb. Heat also makes the food tender, pleasant to eat and more bioavailable — you get the amino acids and other nutrients faster into every cell, which is hungry for fuel.
The activity of heat, the acidity of the stomach and the action of the enzyme rennin (usually added in the production of cheeses) also explains why milk is coagulated or clotted in the stomach so easily. The breakdown of protein molecules is truly spectacular: an average protein molecule is split up into about 500 amino acid molecules during digestion.
When food is heated, denaturation breaks the bonds in protein molecules — a natural first step in making the nutrient easily digestible. Heat squeezes the water out of the protein, molecules recombine, or ‘coagulate’, clump together and toughen. This explains why meat shrinks in volume when cooked.
The same protein denaturation happens when you put the food in your mouth, chew, swallow and let it slide down your pipe all the way to the small intestine. The acidity of gastric juices, 25 human gastrointestinal digestive enzymes and at least 11 polypeptide gastrointestinal hormones denatures, or straightens, the twisted protein molecular chains making them more bioavailable for the cells.
So basically, cooking your food pre-digests it and reduces the amount of work the body has to do. Does it mean that cooking makes no nutritional damage to the proteins themselves? It depends. Cooking can result in some vitamin and mineral losses and may cause sugar molecules to cross-link with proteins. At high temperatures, some protein may be rendered unavailable which reduces protein bioavailability. Several amino acids really hate the heat: lysine, cystine and glutamine residues bond from over-cooking.
It has been found that beef cooked for 3 hours at 120°C loses one fifth of its lysine content. If you raise the temperature by another 40 degrees, the amount of amino acid lost will go up to one half.
Research has also found that fish meat heated for 10 minutes at 130°C showed a 1.5 per cent decrease in protein digestibility. If you cook fish in the presence of potato starch, soy oil or salt, the amino acid content will be decreased by up to six per cent.
Now, take a close look at these numbers. If you’re a 100 kg man who eats two grams of protein per kg of body weight, you eat around 200 grams of protein every day from cooked food.
A loss of 1.5 per cent of the amino acid content is really nothing! You still get 98.5 per cent or 198 grams of protein and lose only 3 grams or so.
Cooking is essential when it comes to beans. Heat improves protein absorption in soy by deactivating a chemical known to block a key protein digestive enzyme. Freezing and canning don’t appear to hamper protein utility. But if you leave any protein-carb-containing powder in a moist, warm place, the nutrients will start creating bonds between them, which will impair full digestion and absorption of amino acids and many of them will be flushed out in the urine.
When it comes to gaining muscle, there are three cardinal rules: train, rest and eat protein. But even if first two rules with nitty-gritty precision, you still can’t build muscle without the critical amino acids that protein provides, especially before and after the workout. This is where protein supplements from easily digestible shakes and, to a lesser extent bars, become handy.
The biggest advantage of supplements is convenience, digestibility and their well-balanced profile.
Shakes are easy to consume, handy to grab, and travel through the gastrointestinal tract faster than solid food. In this sense, protein supplements from reputable companies stand up to their promises. Who has time and energy to buy, prepare, cook and eat a messy shrimp stir-fry every three hours in order to stay in positive nitrogen balance? And forget eating out — most fast-food places deliver meals with an entire day’s worth of calories!
Protein supplements can help you meet all of your protein needs for muscle growth. Do supplements and shakes build denser, leaner, stronger muscles faster while shedding kilos of fat you have securely deposited on places I don’t want to mention? Sadly, there is virtually no proof that the newly-researched ‘scientifically created’ liquid protein-carb complexes will actually produce better muscular growth than whole foods.
What about amino acid pills? Well, they are simply pre-digested protein blocks that don’t offer you any more nourishment than meat or cheese once they meet your internal digestive organs designed by Mother Nature to efficiently process whole foods.
Protein from whole foods
Whole foods have a major advantage over protein supplements — they stimulate the metabolism more and take more time and energy to be digested and absorbed than shakes. This is known as the Thermic Effect and while all protein scores the highest — around 30 per cent of all the energy it provides is used up in processing — your body uses more energy to metabolise steak than a protein shake. Fat has a Thermic Effect of around 3 per cent and carbohydrates range from five to 30 per cent of all available calories.
If you are seeking fat loss and want to delay the satisfying effects of protein, then real, natural, least-processed foods which have minimal amounts of fat (such as chicken breast, eggs, lean beef and pork, low-fat dairy, fish and seafood) are your best choices. This means that out of 300 calories of a protein food, such as found in a large chicken breast, you can get 50-60 grams of protein and the net amount of calories left over after processing it is only 210-230.
The best suited methods for cooking protein-packed meats, fish, poultry and seafood are grilling, baking or microwaving with some herbs and spices. The extremely beneficial essential amino acids and fats will keep products moist and there is a minimal loss of nutrients, very little coagulation and the bioavailability is superb.
The protein diet answer: eat, drink and get healthy!
Should you eat food or take supplements? The answer is both, of course! Foods and supplements are great and there are different times when they best do their bodybuilding magic. Just remember that supplements are just that — supplements to the natural wholesome healthy diet, which is meant to consist of food made by nature. Food should be your priority; no bar, shake or pill will ever replace all the goodness of the meals made from scratch.
Protein has to be at the top of the nutritional requirements, whichever way it comes to the diet. Despite what the flashy ads tell you, pre-digested protein and individual amino acids won’t build more or bigger muscles than omelettes, steaks or cottage cheese.
Focus on real food and don’t believe the hype. Remember that protein is a complex nutrient that consists of many different proportions and variations of amino acids. By the time it gets absorbed into the bloodstream, all your body knows is how much of each amino acid was present in the food you ate. Beyond that, it makes no difference in what form you get your protein, as long as it’s a complete protein and sufficiently digestible. Supplements will not fully compensate for not eating properly. Make food, not supplements, your priority and you will be much healthier.
Boirie, Y. et al. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc National Acad Sci, 94: 14930-14935, 1997.
Carraro, F., et at, Effect of exercise and recovery on muscle protein synthesis in human subjects. Amer Journal of physiology, 259: E470, 1990.
Dillon EL, Sheffield-Moore M, Paddon-Jones D, Gilkison C, Sanford AP, Casperson SL, Jiang J, Chinkes DL, Urban RJ. (2009) Amino acid supplementation increases lean body mass, basal muscle protein synthesis, and insulin-like growth factor-I expression in older women, J Clin Endocrinol Metab. 94(5):1630-7.
Evans WJ. (2001) Protein nutrition and resistance exercise. Can J Appl Physiol. 2001;26 Suppl:S141-52.
Fujita, S., et al. (2006) Amino acids and muscle loss with age. J Nutr. 136:277S-280S.
Henderson et al. (2009) Potential Application of Essential Amino Acid Supplementation to Treat Sarcopenia.J Clin Endocrinol Metab. 94: 1524-1526.
Katch, Katch & McArdle, Exercise Physiology; Energy, Nutrition and Human Performance, Wiliams and Wilkins, 1996.
Lean, M.E.J. (ed), Fox and Cameron’s Food Science, Nutrition and Health, 7th Edition
Lemon, Peter, Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle? Nutrition reviews, 54:S 169-175, 1996
Lemon, Peter, Protein and Exercise: update, Medicine and Science in Sports and Exercise, Vol 19, No. 5, S179 - S190, 1987.
Rieu, I., et al. (2006) Leucine supplementation improves muscle protein synthesis in elderly men independently of hyperaminoacidemia. J Physiol. 575:305-315.
Seidler, T, Effects of additives and thermal treatment on the content of nitrogen compounds and the nutritive value of hake meat. Die Nahrung, vol. 31, no. 10, pp. 959-970, 1987.
Sheffield-Moore M et al. (2006) Amino Acid Supplementation and Skeletal Muscle Metabolism in Ageing Populations. Hormone Research. 66 (1): 93-97.
Volpi E, Kobayashi H, Sheffield-Moore M, Mittendorfer B, Wolfe RR. (2003) Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults, Am J Clin Nutr. 78(2):250-8. IM