So you pop along to a shop and are then faced with a bewildering range of protein powders and ready-to-drink protein shakes. The choice can seem problematic, so how should you make an informed choice?
Firstly, you should be aware that the daily protein intake to remain healthy is around 0.8g per kg body weight for a sedentary person and that this value increases to between 1.5 to 2g per kg body weight per day for athletes. If an athlete is engaged in resistance type training the amounts should favour the upper value (i.e. 2 g per kg) and if training is more endurance based the slightly lower end of the range (i.e. 1.5 g per kg).
For a busy person, it is conceivable that 25-50% of the daily protein intake can be from protein supplements in order to achieve the correct amounts – this is particularly so for a heavy person over 100kg in weight (see how easy it is to eat 200g of protein a day through foods i.e. 100kg person needing to consume 2g per kg per day requires 200g of protein!).
As a rough rule of thumb, consider all meats and fish to contain around 25-30g of protein per 100g, an egg has about 7g, and a pint of milk about 17g, so to get 200g from foods may require three chicken breasts, two eggs, and a pint of milk. Of course there are other protein-based foods and so it is feasible to eat enough protein.
However, busy individuals often require a ‘quick fix’ of protein before and/or after training or as a snack. So what type of protein should you reach for?
The choices for protein supplements are essentially between whey, casein, and soy, although other forms are available. Whey and casein are derivatives of milk, and are present in a ratio of 20:80 in cow’s milk, where casein is the predominant type of protein and is obtained from the curds formed. Soy, on the other hand, is from soya products and so more amenable for vegans and some strict lactose intolerant individuals.
Two major considerations when choosing a protein source are (a) how much protein is in the product, and (b) what is the amino acid composition of the protein? Both of these considerations are concerned with ‘quality’ of protein in the supplement.
Whey and casein products are invariably mainly protein (I wouldn’t chose a protein powder or drink with less than around 70-80% protein) whereas, until recently, soy has been considered ‘inferior’ in terms of the actual amount of protein (just look on the label and read how much actual protein is present). Since amino acids are the essential constituents of any protein, and that around eight amino acids are termed essential, it is crucial that the protein product contains sufficient of each of these essential amino acids (EAAs). Whey, casein, and soy proteins all contain sufficient of the EAAs, and provide a good source from a sports supplement perspective.
However, a rider must be added to the last statement, and that is the key amino acid which promotes muscle recovery and muscle build is leucine (one of the three so-called branched chain amino acids or BCAAs). In essence, the higher the leucine content of the protein the better from a muscle perspective. In this regard, whey proteins score more highly than soy and casein i.e. the leucine content is significantly higher.
Since whey and casein possess all the essential amino acids, are there any differences between them in terms of their profiles? Table 1 highlights the EAA and BCAA profiles of various protein sources. The results demonstrate that whey protein contains significantly greater amounts of the amino acid leucine than the others, and this may confer some advantage for muscle protein synthesis and recovery following exercise. Furthermore, whey proteins have advantages in relation to their overall BCAA and EAA contents.
Whey is classified as a ‘fast’ protein due to the rate at which its consumption leads to an increase in amino acid availability in blood, whilst casein is a ‘slow’ protein since it curdles in the stomach and is more slowly digested and absorbed. This may be important for athletes after training or even between daily training bouts with short recovery periods, where a ‘fast’ protein such as whey may be preferred. On the other hand, casein may prove beneficial as a bedtime product since it is released slowly whilst sleeping and so helps muscle recovery at night.
The rate of uptake and the higher concentration of leucine availability may be predictive of the muscle protein synthesis response, which some scientists suggest helps explain the superiority of whey versus casein or soy at stimulating muscle recovery after training.
Whey protein is categorised, commercially, as either whey protein concentrate (WPC), whey protein isolate (WPI), or whey protein hydrolysate (WPH). WPC contains 59% to 89% total protein by volume (g/100 g), with the remaining nutrient composition coming from carbohydrate (predominantly lactose) and fat. WPC-70 and WPC-80 (70% and 80% concentrations of protein, respectively) are the most common forms of whey protein used in sports supplements, largely due to pricing and possibly improved taste characteristics when compared to either WPI or various forms of WPH.
The low lactose content of WPI may be of importance for individuals with lactose intolerance, especially when large amounts of whey or other dairy products are consumed daily. Also, WPI may be more suitable than WPC when used in combination with a very-low-carbohydrate (ketogenic) diet for fat loss.
What is the evidence regarding the likely benefits of whey vs casein or soy in the scientific literature?
One recent study explored the effects of whey, casein, and soy ingestion after resistance exercise. The investigation highlighted the rapidity of appearance of both leucine and the EAAs with whey compared with casein and soy. Participants exercised first, before drinking whey or soy or casein with the same amount of EAAs (i.e. 10g). This meant that the total amounts ingested were 21.4g of whey, 21.9g of casein, or 22.2g of soy. A significantly higher (and faster) leucine appearance was observed in blood following whey ingestion than casein or soy in the first 60-90 minutes. It is quite likely that the reasons for the differences were due (a) to the faster digestion and absorption of whey, and (b) to an extent in the marginally higher levels of leucine in whey (i.e. 2.3g in whey, 1.8g each in both casein and soy).
What was also interesting in this study was that whey ingestion resulted in a greater increase in muscle protein synthesis compared with casein and soy. It is possible that in the short time scale of this study (i.e. three hours), the more rapid availability of leucine from whey helped enhance muscle protein synthesis. It may also be suggested that IF the same amount of protein was ingested without equalising the EAA content, a further advantage of whey may have been noted.
A very recent investigation has shown that ingesting casein before bedtime after an evening training bout significantly improves muscle protein synthesis overnight. The ‘slow’ breakdown and release of casein during sleep aids recovery of muscle.
Protein synthesis is only one aspect of what goes on in a muscle or the body – the other being protein breakdown. During exercise, protein breakdown increases whilst protein synthesis is reduced – so there is a net balance of protein in the muscle that is negative i.e. muscle loses more protein than it gains during exercise. This is an inevitable consequence of exercise; but don’t be worried because (a) it can be reduced by ingesting protein or amino acids before and after the exercise bout, and (b) the reverse occurs in the recovery period after exercise (so make sure you recover well!). If you fail to eat/drink protein before or after exercise, there is a negative protein balance over a 4 hour period i.e. muscle is lost!! You have been warned – do NOT exercise without ensuring that you ingest protein either before or after the exercise bout.
– Athletes have a daily protein requirement of between 1.5-2g per kg body weight per day.
– Protein supplementation can play an important role in the life of a busy athlete, and can provide as much as 25-50% of the daily intake.
– The current major types of protein supplement include whey (concentrate, isolate, or hydrolysed), casein, and soy.
– Whey proteins generally confer an advantage over the others because of the higher EAA, BCAA, and leucine contents.
– Soy proteins are advisable for vegans and lactose intolerant individuals.
– Getting into the habit of consuming rapidly digested proteins (whey) after resistance exercise provides an anabolic advantage that leads to greater hypertrophy or faster muscle recovery.
– Casein ingestion is recommended at night (before bedtime) as it stimulates muscle recovery whilst sleeping.
Professor Don MacLaren is part of the team who have developed Nutrition X’s range of Informed-Sport certified products, which have become the No.1 choice of sports nutrition for numerous elite athletes, amateur sports people and casual gym users alike.
For more information, or to discuss your sports nutrition requirements, please contact Don MacLaren via www.nutritionx.co.uk
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BIOGRAPHY: Daniel Sturridge
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