Ever wondered about the amount of protein you need to eat on a daily basis to stay healthy? Or about protein loading for athletes? DietDoc answers a few important protein questions…
How much protein do we need?
The recommended daily allowance (RDA) for proteins is about 60g a day on average for adults, between 15 and 28g a day for children (aged 1-10 years), and about 14g a day for infants (0-1 year). These RDAs are relatively low, and most people eating a western diet that contains meat, fish, eggs, cheese, milk and dairy products will have no problem consuming these amounts of protein on a daily basis.
In South Africa, most economically advantaged people tend to eat far too much protein, which not only puts a strain on the kidneys, but also contributes to excessive intakes of saturated fat and cholesterol, which are implicated in heart disease and certain types of cancer.
Most readers need, therefore, not worry that they are not getting sufficient protein.
Certain age groups and people with specific conditions have increased protein needs. Whenever growth takes place (infants, young children, teenagers, pregnant and lactating mothers), the need for high-quality protein increases.
During growth phases it is a good idea to ensure that more low-fat animal protein is eaten, e.g. milk and eggs for infants, or low-fat milk, lean meat and fish for pregnant and lactating women. This is to ensure that individuals who are growing obtain sufficient essential amino acids to build new tissue.
People suffering from tissue-wasting diseases such as TB, cancer and HIV/Aids, also have an increased need for high-quality protein, which can be met by eating a portion of meat or fish, or an egg a day, and using milk, yoghurt and cheese.
Additions of plant proteins in the form of legumes (dry beans, peas, lentils and soya products) can help to ‘stretch’ animal proteins in patients who required protein to combat muscle or lean tissue wasting, and cannot afford to eat protein derived from meat or fish in adequate quantities because of economic constraints.
Protein requirements for athletes
Athletes have always believed that they require masses of protein to ‘build muscle tissue’ and many readers list the different amino acid supplements they use on a daily basis. Intensive research has, however, not been able to prove that eating large quantities of protein, or using amino acid supplements either increases muscle mass or improves athletic performance. In fact, the opposite may be true.
Research has also shown that individuals who train hard or participate in strenuous exercise (not just 30 minutes every second day) need 1,5 g of protein per kilogram of body weight per day. A young, healthy 70 kg male, adolescent athlete who is exercising at full potential who requires 1,5 g/kg body weight of protein, needs a total of 105g a day. This is considerably less than the vast amounts of protein some athletes, and body builders in particular, ingest on a daily basis.
Amino acid supplements
Many athletes also swear by amino acid supplements. Once again, research has shown that eating high-protein foods, which contain a balanced mix of the essential amino acids, will probably give better results than these supplements.
Taking amino acid supplements can have the following negative effects on health and performance:
Excessive intakes can:
Lead to dehydration - a condition that severely impairs performance, which can result in kidney damage
Cause the kidneys to excrete more calcium, which weakens the skeleton, particularly in young athletes who are still growing
Cause weight gain, which is not desirable in many branches of athletics
Cause stress to the liver and kidneys
Cause deficiencies of vital nutrients, like iron, niacin, thiamin and omega-3 fatty acids, if amino acid supplements are used instead of protein foods
Taking only one or two amino acids, such as arginine and lysine, can also interfere with the uptake of other essential amino acids.
So if you are hooked on excessive protein or amino acid intakes, be careful that you don’t damage your body and defeat the object of the exercise.
Role of carbohydrate
In general, athletes should ensure that they have an adequate carbohydrate intake to supply the energy they require for their increased needs, and that they do not have to utilise the protein in their diet as a source of energy.
Carbohydrate has a ‘protein-sparing effect’, so ingest sufficient carbohydrate (7-10g/kg body mass/day, or 350-700g of carbohydrate/day for a 70 kg athlete) and 1,5g of protein/kg body mass a day, for optimum athletic performance - not the other way round.
– (Dr IV van Heerden, DietDoc)
Any questions? Ask DietDoc
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