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Sports Nutrition Supplements - The Importance of Protein - Part Three

The importance of protein as a sports nutrition supplement.

Read why proper protein supplementation is so key to helping you achieve your training goals

HOW CAN I MEET MY PROTEIN NEEDS?

Protein intake is usually proportional to total calorie intake so the more food you eat, the greater the chances of meeting your protein needs. If you reduce your calories, you may find it more difficult to meet your protein needs so a few dietary adjustments may be needed. Additionally, if you eat a vegan diet or eat very few animal sources of protein, it may be more difficult to meet your needs. Animal sources generally provide a better amino acid profile but some foods (such as meat and cheese) are high in saturated fat. Keep these to a minimum and choose lean and low-fat versions.

To ensure your protein requirements are adequate you can estimate how much protein you should eat per day in one of two days:

1 - From your energy intake

Calculate your energy intake (your maintenance calorie intake) either from your actual food intake over 3-7 consecutive days using food tables, or using the formulae based on your resting metabolic rate (RMR). Multiply your energy intake by 12% and 15% then divide by 4 to give you your recommended protein intake in grams.

Example:

Energy intake = 3000 kcal
Calories from protein

= (a) 3000 x 12& = 360

= (b) 3000 x 15% = 450
Protein intake

= (a) 360 ? 4 = 90 g

= (b) 450 ? 4 = 112.5 g
i.e. between 90 ? 112.5 g/day

2 - From your body weight

Calculate your daily protein requirement from your body weight by using the guidelines above.

Examples:

(a) For an endurance athlete weighing 70 kg
70 x 1.2 = 84 g
70 x 1.4 = 98 g
i.e. between 84-98 g/day
(b) For a strength or power athlete weighing 70kg
70 x 1.4 = 94 g
70 x 1.8 = 126 g
i.e. between 98-126 g/day

Is more protein better?

A protein intake above your optimal requirement will not result in further muscle mass and strength gains. In a study carried out at McMaster University, Ontario, strength athletes were given a low-protein diet (0.86 g/kg bogy weight/day ? similar to the RDA), a medium-protein diet (1.4 g/kg body weight/day) or a high protein diet (2.3 g/kg body weight/day) for 13 days. The low-protein diet, which was close to the RDA for sedentary people, caused the athletes to lose muscle mass. Both the medium and high protein diets resulted in an increased muscle mass, but the amount of the increase was the same for the two groups. In other words, no further benefits were gained by increasing the protein intake from 1.4 g to 2.4 g/kg body weight/day.

Similar findings were recorded at Kent State University, Ohio. Researchers gave 12 young volunteers either a protein supplement (total daily protein was 2.62 g/kg body weight) or a carbohydrate supplement (total daily protein was 1.35 g/kg body weight) for one month during which time they performed intense weight training 6 days a week. Nitrogen balance measurements were carried out after each diet and the researchers found that an intake of 1.4-1.5 g/kg body weight/day was needed to maintain nitrogen balance, although strength, muscle mass and size were the same with any level of protein intake. The researchers concluded two main points. First, strength training approximately doubles your protein needs (compared with sedentary people). Secondly, increasing your protein intake does not enhance your strength, mass or size in a linear fashion. Once your optimal intake has been reached, additional protein is not converted into muscle.

Is too much protein harmful?

Consuming more protein than you need certainly offers no advantage in terms of health or physical performance. Once your requirements have been met, additional protein will not be converted into muscle, nor will it further increase muscle size, strength or stamina.

The nitrogen-containing amino group of the protein is converted into a substance called urea in the liver. This is then passed to the kidneys and excreted in the urine. The remainder of the protein is converted into glucose and is used as an energy substrate. It may either be used as fuel immediately or stored, usually as glycogen. If you are already eating enough carbohydrate to refill your glycogen stores, excess glucose may be converted into fat. However, in practice this does not occur to a great extent. Fat gain is usually the result of excessive calorie consumption, in particular of fats. Recent studies have shown that eating protein increases the metabolic rate, so a significant proportion of the protein calories are oxidised and given off as heat. Thus, a slight excess of protein is unlikely to be converted into fat.

It was once thought that excess protein may cause liver or kidney damage as it places and undue stress on these organs. This has never been demonstrated in healthy people, though so it remains only a theoretical possibility. Those with liver or kidney problems, however, are advised to consume a low-protein diet.

It has also been claimed that eating too much protein leads to dehydration because extra water is drawn from the body?s fluids to dilute and excrete the increased quantities of urea. Indeed, a study reported at the 2002 Experimental Biology meeting in New Orleans found that high protein diet (246 g daily) consumed for 4 weeks caused dehydration in trained athletes. Their blood urea nitrogen ? a clinical test for proper kidney function ? reached abnormal levels and they produced more concentrated urine. According to the researchers at the University of Connecticut, this could have been avoided by increasing their fluid intake. This is unlikely to be a problem if you drink enough fluids.

Finally, there is some evidence dating from studies conducted in the early 1980s that high-protein diets cause an excessive excretion of calcium, increasing the risk of osteoporosis. However, a more recent study at the University of Maastrict, Belgium, found that a 21% protein diet produced no negative effect on calcium status compared with a 12% protein diet.

In conclusion, eating too much protein is unlikely to be harmful but it certainly offers no advantages.

Should I consume more protein if I am on a fat-loss programme?

When cutting calories to lose body fat you losing muscle mass as well. A higher protein intake can offset some of the muscle-wasting effects associated with any weight-reducing programme. Most researchers recommend increasing your protein intake a further 0.2 g/kg body weight. Thus, an endurance athlete would need as much as 1.6 g/kg body weight/day; and a strength athlete would need up to 2.0 g/kg body weight/day. For example, a 70 kg endurance athlete would need to consume 70 x 1.6 = 112 g protein/day. If you are consuming 2000 kcal a day, that would be equivalent to 22% of your total calories (i.e. 112 x 4 divided by 2000).

SUMMARY OF KEY POINTS

• Protein is needed for the maintenance, replacement and growth of body tissue. The body also uses protein to make the many enzymes and hormones that regulate the metabolism, maintain fluid balance, and transport nutrients in and out of cells.
  Athletes require more than the current RDA for protein of 0.75 g/kg body weight/day for the general population.
  
• Additional protein is needed to compensate for the increased breakdown of protein during intense training for the repair and recovery of muscle tissue after training.
  
• Strength and power athletes have additional needs to facilitate muscle growth.
  
• For endurance athletes, the recommended intake is 1.2-1.4 g/kg body weight/day. For strength and power athletes, the recommended intake is 1.4-1.8 g/kg body weight/day
  
• Protein breakdown is increased when muscle glycogen stores are low, e.g. during intense exercise lasting longer than 1 hour, or during a calorie/carbohydrate-restricted programme.
  
• Protein intake above your optimal requirement will not result in further muscle mass or strength gains.
  
• Athletes should be able to meet their protein needs from a well-planned diet that matches their calorie needs. Low-fat protein sources are advised.
  
• Vegetarian athletes can meet their protein-rich plant sources eaten in the right combinations so that protein complementation is achieved.

Paul Jordan is a sports nutrition consultant for the Sports Nutrition Company. SNC is a UK based sports supplements supplier. http://www.sncdirect.com

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