Explain the Population Survey of Dietary Intakes of Nutrients?

The basis of this method rests on the premise that average dietary intake of nutrients by healthy members of a group of individuals at a specific life stage and gender represents the requirement of this group. This was the only method available for a long time to estimate the nutrient needs. All early recommendations were based on this method. The limitations of the method are that since the average is calculated from usual intakes of healthy individuals eating to appetite, the method can both over or underestimate the requirements. The limitation of this method is best illustrated by the early recommendations for protein. The first ever recommendation that was formally adopted put the protein requirement of adult man as 80 g per day. Some years later, Chittenden, a German nutrition scientist based on experiments on him recommended that for good health, an adult man required no more than 50 g protein per day.