Under the right to know what is in a packet of food, industry is forced to list some of the nutrients as percentage of DV (Daily Value), based on RDI or RDA recognized internationally in order to keep consumers informed about the nutrition status of the product. RDA is supposed to give information regarding the recommended dietary allowance and RDI, recommended dietary intake. DV per serving is derived based on RDA or RDI. RDI values reflect the adequacy of nutrient intake sufficient to meet the needs of 97-98% of healthy individuals. RDI is calculated based on certain assumptions which include (a) fat based calories constitute 30% of total calorie needs of 2000 kC (b) calories from saturated fat is 10% of total calories (c) carbohydrates contribute 60% of the energy (d) protein calories make up of 10% of total energy in the daily diet and (e) dietary fiber is 11.5 gm per 1000 calories consumed. RDA system started in 1941 in the US and the standards were being revised every 5-10 years. In fifties of the last millennium, the concept of nutrients per serving was implemented for better consumer understanding of the packed foods.
It was in 1997 that new standards were evolved and Dietary Reference Intake (DRI) became the accepted norm. Four types of DRI values were evolved which included EAR ( Estimated Average Requirement), RDA (Recommended Dietary Allowance), AI (Adequate Intake) and UL ( Tolerable Upper Limit). As far as consumers are concerned, DRI may not be of much relevance as it is meant for nutritionists and dietitians for menu planning programs. RDI values now being commonly used for calculating DV are more or less same as the RDA values which were the norms till 1968. Besides these confusing terminologies, there is also SONA values (Suggested Optimum Nutritional Allowance), which happened to be the most comprehensive data on nutrients evolved over many years of studies with thousands of healthy people. SONA values are some time 20 times that of RDI because it takes into consideration the positive benefits of nutrient intake while RDI values are for minimum nutrition below which there can be deficiency symptoms.
One of the critical factors that can cause enormous variations in the requirements of nutrients for individuals is the efficiency of digestion and absorption which can vary considerably amongst people. On an average most people can only absorb 10% of the nutrients ingested and it is estimated that only 1-3 % of the total population with high absorption efficiency must be getting sufficient nutrition if one goes by only RDI in stead of SONA. The ideal diet concept emerged only because empirically eating certain foods in certain quantities can keep humans healthy but this information cannot be translated into nutrients consumed directly because of the bio-efficiency of natural foods in terms of better utilization of different nutrients. Human body is very vulnerable because of its inability to make on its own some of the nutrients vital for life which include 23 vitamins and minerals, 8 essential amino acids and 2 essential oils. They must be supplied from the diet.
In the above context, what purpose the nutritional labeling serves is a debatable point. If a manufacturer declares that his product contains 20% of DV of a particular nutrient, it does not guarantee that body can get the declared quantity by consuming the product as per the serving size. There are other imponderable factors like gycemic index, protein efficiency ration, type of fat in the diet, type of fiber etc which determine the ultimate quality of the product. Unless these factors are integrated into nutritional value of processed products, the present labeling system can, at best be, an approximation. In spite of the existence of RDI since 1941 and introduction of mandatory labeling for better consumer discretion in choosing healthy foods by the US, that country is facing the biggest health crisis world has known in the form of Obesity, CVD, Diabetes, Hypertension, Cancer of various types and Alzheimer's disease.
In India can we think in a different way? In stead of the US style of nutritional labeling, is it not better if only the proximate composition of the product is declared for the consumers to have an idea of the food he is buying? Probably any negative aspect associated with that type of product could also be highlighted including allergy, cholesterol, transfats, etc for which there are no upper limits prescribed. It is also a good idea to put on each label the composition of an ideal food as a part of nutritional education of the consumers.