TERMINOLOGY.

The revised edition of the dietary standards is changed from "Recommended Dietary Allowances (RDA)" to Recommended Energy and Nutrient Intakes (RENI) to emphasize that the standards are in terms of nutrients, and not foods or diets. RENIs are defined as levels of intakes of energy and nutrients which, on the basis of current scientific knowledge, are considered adequate for the maintenance of health and well being of nearly all healthy persons in the population. For most nutrients, they are equal to the average physiologic requirement (AR), corrected for incomplete utilization or dietary nutrient bioavailability, plus two standard deviations (SD), or twice an assumed coefficient of variation (CV), to cover the needs of almost all individuals in the population. In the case of nutrient for which data on AR are insufficient, the RNI is an "adequate intake" (AI) which is based on the experimentally observed average intake of healthy individuals. For energy, the recommended intake level is set at the estimated average requirement of individuals in a group (no SD), since intakes consistently above the individual’s r4equirement lead to overweight or obesity.

POPULATION GROUPINGS.

The population groups essentially follow the (FAO/WHO, 2002) groupings. These are similar to those of the 1989 Philippine RDA, except for the cut-off for children, which is now 18 years rather than 19 years, consistent with the International Reference Standards (IRS) for growth.

REFERENCE WEIGHTS.

The reference weights for adults are the average weights derived from the 1998 National Nutrition Survey (NNS). These weights are higher by 3 kg in the male and 2 kg in the female than the reference weights used in the 1989 Philippine RDA edition. The reference weights for children are set higher than the average weights following the International Reference Standards except in late adolescence.

RECOMMENDED ENERGY AND NUTRIENT INTAKES.

For most nutrients, recommended nutrient intakes (RNIs) for infants, from birth to <6 mo are "adequate intakes" (AI) derived from the intakes of fully breastfed infants, based on an average daily milk consumption of 750 mL for the first six months multiplied by the nutrient concentration in breast milk. For older infants (6 to <12 mo), the RNI includes the amount of nutrient provided in both breast milk (based on average breast milk consumption of 600 mL) and complementary foods. If data on the nutrient intake from complementary foods is not available, the recommended intake is extrapolated from the RNI of younger infants or from adult recommendations. For children 1-18 y, the AR for most nutrients is extrapolated from adult values. The ARs are then increased by 2SD or 2CV to derive the RNI that would cover the needs of 97.5% of the individuals in the group. Additional requirements during pregnancy are based on estimates of amounts laid down in fetal and maternal tissues, while those for lactating women, are based on amounts secreted in breast milk. These amounts are then added to the requirements of non-pregnant, non-lactating women.

ENERGY. The recommended energy requirement of an individual is the level of energy intake from food that will balance energy expenditure when the individual has a body size and composition, and level of physical activity, consistent with long-term good health as well as allow for the maintenance of economically necessary and socially desirable physical activity (FAO/WHO/UNU, 1985).  The recommendation for infants is based on new estimates derived from total energy expenditure (TEE) by the doubly labeled water (DLW) method, and on energy deposition based on rates of protein and fat gains.  The recommendations for children are based on an extensive review on energy expenditure, growth and activity patterns of free-living, healthy children and adolescents.  Estimation of TEE also considered studies using DLW and heart rate methods.  Time-motion observations and activity diaries are used in these studies to gather information on the activity patterns and habitual physical activities.   For adults, the Oxford equation (Henry, 2001), which is based on BMR data that included populations from the tropical areas, is used rather than the Schofield equation (Schofield, Schofield, and James, 1985) used in earlier estimations.  For older adults, the TEE is reduced in accordance with FAO recommendation (FAO/WHO, 1973).   The recommended energy intakes at varying level of physical activity are presented in Table 1.

PROTEIN. A safe protein intake level for adults is defined as the lowest level of dietary protein intake that will balance the losses of nitrogen from the body in persons maintaining energy balance at modest levels of physical activity (FAO/WHO/UNU, 1985).  The recommended intake levels for children are based on the safe level of protein intakes estimated by the FAO/WHO/UNU (1985) for a reference protein (egg or milk) adjusted for the protein quality of Filipino rice-based diets of 70% protein digestibility corrected amino acid score (PDCAAS).  These values are very close to estimates obtained from direct studies on Filipinos consuming usual rice-based diets.        

VITAMIN A. The recommended intake levels for vitamin A correspond to the safe levels of intake based on the average amounts of vitamin A required to maintain a given body-pool size in well-nourished individuals. For adults, the RNI is equivalent to the estimated average requirement plus 2SDs. When recommendation for children are estimated by extrapolation from adult recommendations, the resulting values are lower than the reported intakes of children, 0 to 6 y in populations where evidence of vitamin A deficiency (VAD) is rare. The Committee therefore adopts the higher recommendation given by the FAO/WHO (2002).

THIAMIN (VITAMIN B1).  The Institute of Medicine, Food and Nutrition Board (IOM-FNB) (1998) and FAO/WHO (2002)  recommendations, which are both based on the average requirement for normal erythrocyte transketolase (ETK) activity and urinary thiamin excretion and twice an assumed CV of 10% to cover the needs of 97.5% of individuals in the group, are adopted.  The IOM-FNB and FAO/WHO-derived estimates, adjusted for Philippine reference body weighs, are similar to the 1989 RDAs which were then based on a local study done in the '60s on 10 adult Filipinos. The recommended intake level for infants from birth to six months is  based on the reported mean thiamin content of breast milk obtained from mothers without beriberi.  It may be necessary to give supplements as a protective measure against infantile beriberi.      

RIBOFLAVIN (VITAMIN B2). The RNI is derived from the requirement estimate of the IOM-FNB (1998) which is based on the amount of riboflavin intake to maintain riboflavin status of  satisfactory erythrocyte glutathione reductase activity (EG-AC) level, as criterion of adequacy.  These intake levels, which conform with the FAO/ WHO (2002) recommendations, are close to the 1989 recommendations which were based on requirement estimates obtained from Filipino adults consuming rice-based diets.      

NIACIN. The FAO/WHO (2002) and IOM-FNB (1998) estimates, which are based on the amount of niacin intake corresponding to an excretion of N'methyl-nicotinamide that is above the minimal excretion at which deficiency symptoms occur, are also adopted for Filipinos.  These values are lower than the 1989 RDA because no correction is made for bioavailability.  The bioavailability of niacin is not considered in setting the RDA because of "lack of data on which to base the correction value" (IOM-FNB), 1998.      

FOLATE.  The  FAO/WHO (2002) and IOM-FNB (1998) recommendations are also adopted for Filipinos.  The requirement estimates of these two bodies are derived from the amount of folate that will maintain adequate folate stores based on erythrocyte folate and plasma homocysteine levels.  To meet the new higher recommendations, higher intakes of vegetables and fruits, which are among the best sources of folate, are recommended.      

CALCIUM. The RNIs for Filipinos are allowances based on theoretical calcium requirement estimates which considered low animal protein intake levels.  The FAO/WHO (2002) provided these estimates for possible  application to countries where the animal protein intake per capita is around 20-40 g only compared with 60-80 g in developed countries.  These allowances take into account the need to protect children in whom skeletal needs are much more important determinants of calcium requirement than are urinary losses and in whom calcium supplementation has been found to have a beneficial effect in children accustomed to low calcium intakes.     

IRON.  The recommended intake for iron is based on the amount of dietary iron needed to meet absorbed iron requirements.  This would correspond to the amount needed to cover basal losses plus growth for children and menstrual losses for women of reproductive age, adjusted for bioavailability of iron in typical complete meals consumed by Filipinos.  The Philippine RNI for iron is based on FAO/WHO (2002) estimates for basal losses, local data on menstrual losses and on bioavailability, iron absorption rates in the average Filipino diets, food consumption surveys, and in-vitro studies on non-heme iron availability from rice-based diets.  For infants, it is assumed that the iron provided by breast milk is adequate to meet the iron needs of infants exclusively fed human milk from birth to 6 mo.  The consumption of iron-rich foods and iron-fortified foods is recommended for women from adolescence onwards.  Iron supplementation is recommended to meet the needs of pregnant and lactating women.  The estimated iron requirement during the first trimester of pregnancy and the first six months of lactation are actually lower than the requirement for menstruating non-pregnant, non-lactating women.  However, the recommended intake for non-pregnant and non-lactating women are adopted to allow for build-up of iron stores during these periods.        

IODINE. The FAO/WHO (2002) recommendations which concur with those of the IOM-FNB are adopted for all population groups, except pregnant and lactating women. The recommended intake level for adults corresponds to the intake necessary to maintain plasma iodide level above the critical limit likely to be associated with the onset of goiter. It corresponds to the daily iodine urinary excretion of 100  µg/L.

The recommended energy and nutrient intakes levels of the above nutrients are summarized in Table 2

CARBOHYDRATES.   Carbohydrates may contribute 55-70% of TDE, 70% of which should come from complex carbohydrates and not more than 10% should come from simple sugars.  Following IOM-FNB (2002) and FAO/WHO (2002) recommendations, a daily intake of 20-25 g dietary fiber for adults is also suggested.       

FATS AND FATTY ACIDS. The recommended intake for Filipinos is 20-30% of TDE for all age groups, except for infants which is 30-40% following the FAO/WHO recommendation.  The lower limit for adults is slightly higher than the minimum of 15% set by the FAO/WHO (2002) to promote absorption of vitamin A which has been found to be generally low in the average Filipino diet. The upper limit is the maximum intake level recommended by most dietary guidelines as a preventive measure against the risk of cardiovascular and other degenerative diseases.

OTHER NUTRIENT RECOMMENDATIONS

RNIs for nutrients not included in previous editions of the RDAs ar erecognized as essential for health.

Table 2: Recommended Energy and Nutrient Intakes

Table 3. Recommended Nutrient Intakes for Other Vitamins and Minerals

RNIs for these nutrients are now available as a result of the development of more precise methods of determining human nutritional requirements.  In the light of the aggressive marketing of dietary supplements, health care professionals need guidance on reasonable intakes of these nutrients.  The 2002 RENI thus provide information on recommendations for vitamins D, E, K, B6, and B12, and minerals such as  phosphorus, magnesium, fluoride, zinc, selenium, manganese, as well as water and electrolytes.

Local data on food composition, deficiency problems, or roles in chronic degenerative diseases, direct studies on requirements, and nutrient-nutrient interrelationship are not available for some of these nutrients.  Recommendations of IOM-FNB, 1997-2002 and the FAO/WHO, 2002 are presented as guidelines.

The RNIs for other vitamins and minerals are summarized in Table 3.

VITAMIN D.     The FAO/WHO and IOM-FNB recommendation of 5 µg/day for adults is based on the amount of vitamin D intake necessary to maintain vitamin D status as indicated by a satisfactory level of serum 25-hydroxy-vitamin  D (25-OH-D).  The recommended intake levels, according to the IOM-FNB, will cover the needs of adults "regardless of exposure to sunlight".   

VITAMIN E. The safe level of intake for vitamin E for adults is 12 mg/day.  The term "safe" rather then "recommended" is used since the value is derived from data for the US population whose mean PUFA intake can be presumed to be  higher than that of Filipinos since the major source in the Filipino diet is the medium-chain saturated fat-rich coconut oil.  High intakes of PUFA are typically accompanied by increased vitamin E intakes.      

VITAMIN K. The FAO/WHO (2002) Expert Panel's recommendation set a daily intake of µg/kg as basis for setting RNI.   The panel also advised that all breastfed infants should receive vitamin K supplementation at birth according to nationally established guidelines.     

PYRIDOXINE (VITAMIN B6).  The RNI for adults of 1.3 mg/day adopted by the FAO/WHO (1998) is based on the amount required for normalization of the tryptophan load test.     

COBALAMIN (VITAMIN B12). The IOM-FNB recommendation of 2.4 µg/day is based on the amount needed to maintain adequate hematological status.       ZINC.  The requirement for adults is based on the intake that will meet the daily absorbed zinc requirements of 0-072 and 0.059 mg/kg for adult males and females, respectively, and adjusted for bioavailability of 30% following the recommendation of FAO/WHO (2002).     

SELENIUM.   The FAO/WHO recommendation of 31 µg/day corresponds to the level of intake that provides adequate reserves based on satisfactory levels of plasma selenium, and of glutathione peroxidase activity.      

PHOSPHORUS.  The RNIs are based on the intake required to maintain serum inorganic phosphate within the normal range.        MAGNESIUM.  The FAO/WHO (2002) recommendation is based on a requirement of 4 mg/kg body weight/ day for adults to achieve a positive magnesium balance.       

MANGANESE.  The IOM-FNB (2002) recommendations is based on the median intake of Americans derived from the US Food and Drug Administration Total Diet Study from 1991-1997.       

FLUORIDE. IOM-FNB recommendations are based on "adequate intakes" that have been found to prevent dental caries.      

WATER AND ELECTROLYTES.     The recommended water intake for adults under average conditions of energy expenditure and environmental exposure is 2500 mL based on a recommended intake of 1 mL per kcal of energy expenditure (NRC, 1989)  (Table 4).  It may be increased to 3735 mL (1.5 mL/kcal) to cover variations in activity level, sweating, and solute load.   Thirst is normally a good indicator of the amount of extra water needed to meet the daily requirement, except for older persons whose thirst mechanism may be impaired.   For infants, a recommended intake of 1.5 mL/kcal of energy expenditure, which corresponds to the water-to-energy ratio in human milk, has been established as a satisfactory level for the growing infant.

         The minimum requirements for electrolytes do not include allowance for large, prolonged losses from the skin through sweat (Table 5).  There is no evidence that higher intakes confer any health benefit.  For adults (>18y), desirable intakes of potassium may considerably exceed the minimum recommendations (~3500 mg).  For children (<18 y) a growth rate of 50th percentile reported by the National Center for Health Statistics and averaged for males and females is assumed (IOM-FNB, 1989).

Table 4 shows the Minimum Daily Requirement for Water, and Table 5 shows the Minimum Daily Requirements for Electrolytes.

Table 4: Minimum Daily Requirements for Water

Table 5: Minimum Daily Requirements for Electrolytes