Part 46 - Protein
Following on from last month’s look at dietary fibre, let’s turn our attention to a different dietary component ‐ protein. I choose this subject because for over a year now I’ve worked with a vegetarian. Sharing an office, we often end up inspecting the other person’s lunch and in our case the contents tend to coincide, other than my habitual addition of chunks or chicken of tuna to the classic pasta salad. For me personally, and with no disrespect for a vegetarian diet, a meal without this component would be somewhat unsatisfying. Could this be born out of habit or could it be a genuine need? Responsible for growth and repair ‐ there’s no doubt that proteins are essential in all diets. Moreover those of you who lead a more active life style, notably athletes, require a larger amount than average ‐ given the growth of extra muscle mass, and the need to repair the damage caused by training. But how much do we need and are there good and bad kinds?
Story Highlights
- In More Detail
- The Sources
- Protein and Exercise
- But What About Quantity?
- Keep It Regular
In More Detail
Although we often refer to protein in the singular sense, there are in fact many different proteins which occur in the range of foods available. On a chemical level these are different compositions of amino acids, which are essential components in many metabolic processes. The body first breaks down the proteins consumed into amino acids which it then uses in the construction of new proteins ‐ growth!
I include this information because of the 22 standard amino acids, there are eight which the body is unable to manufacture and hence must be obtained through diet. In young children there are in fact more ‐ since the body’s metabolic systems are not yet fully developed. For most readers however only the standard eight are relevant and are known as the essential amino acids.
The Sources
Dietary proteins which provide a balanced set of essential amino acids are referred to as: “complete.” These are the proteins found in eggs (notably egg whites), meats, fish and dairy products. Note however that the protein content varies enormously within these sources. The plant sources quinoa, hempseed and buckwheat are almost complete and soya, although lacking a large component, adds sufficient variation to allow even a vegan to obtain all the essential amino acids.
Protein and Exercise
Upping your protein intake will not automatically build muscle. You must first create damage to muscle fibres via strength training and then allow recovery time, during which the body will repair this damage, increasing its own protein mass. For those whose lifestyle demands a high protein intake, meeting the body’s needs can be difficult and rather expensive. Protein supplements claim to rectify this problem by providing the essential quantity of high‐BA proteins and vitamins, aiding recovery and hence preventing fatigue. The composition of such products does however vary drastically, meaning that the quality and the appropriateness vary drastically. Just do your research first and don’t be fooled by the vast amounts of marketing!
But What About Quantity?
Well the percentage of protein by weight is the classic measure. But then there is an additional measure known as Biological Value (BA), which measures the proportion of the protein absorbed from a source ‐ which is retained as part of the protein structure of the body. Complicated huh? Here whey protein and egg whites come out top, with red meats a little further down the list. So a balance between quantity and quality is definitely the key.
As an absolute minimum, grown women should, on average, consume 46 grams of protein per day and men a minimum of 56 grams, corresponding to 0.8 grams per kilogram of body mass. But as soon as you become active then the demand goes up, so it’s better to aim a little higher. In one day the body is able to process a maximum of around 1.4 grams of protein per kilogram of body weight, on the assumption that the consumer’s muscle to mass ratio remains average. Further protein consumed will be used as an energy source or even turned to fat.
Keep It Regular
As with most good things, there is always the possibility of having too much so do remember that, since the breakdown of protein is a metabolic process, it is best to attain your requirement via a regular intake and not through infrequent consumption of vast quantities. In other words ‐ don’t binge!
Furthermore, in a process known as protein turnover, the body constantly breaks down and repairs its own proteins ‐ like muscle mass. We therefore must try to ensure that the net effect is at least one of maintenance, if not growth. This is also the reason why a lack of fast sugars in the blood during short, intense periods of exercise can impede the process of repair. The most quickly attainable energy source is the muscles that are working.
But for those of you on your travels, such training is most likely not on the cards. Still in order to maintain your physical form and not be lacking in energy, a regular and complete intake of proteins is essential. This can be difficult at breakfast, but just remember that even bread is a source of protein, as well as many yogurt based products. So until next month ‐ bon appétit!
‐ David Haw
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