Dietary Reference Intake
Dietary Reference Intakes (DRIs) are a set of nutrient-based reference values designed to plan and assess the dietary intakes of healthy individuals, varying by age, sex, and life stage.[1] These values include four main categories: the Recommended Dietary Allowance (RDA), Adequate Intake (AI), Estimated Average Requirement (EAR), and Tolerable Upper Intake Level (UL).[1] Developed by the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine in collaboration with Health Canada, DRIs provide evidence-based guidelines for nutrient requirements and safety levels applicable primarily to populations in the United States and Canada.[1][2] The RDA is the average daily dietary intake level sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a specific age and gender group.[1] It serves as a goal for individual nutrient intake planning when adequate data are available.[1] The AI is used when insufficient scientific evidence exists to establish an RDA; it represents a recommended intake based on observed or experimentally determined approximations of nutrient intake by a group (or groups) of healthy people that are assumed to ensure nutritional adequacy.[1] The EAR estimates the daily intake needed to meet the requirements of 50% of healthy individuals in a life stage and gender group, making it useful for assessing the prevalence of inadequate intakes within populations and for planning group diets.[1] Finally, the UL defines the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population, helping to prevent nutrient excesses from foods, supplements, or fortified products.[1] DRIs evolved from the Recommended Dietary Allowances (RDAs), which were first published by the National Academy of Sciences in 1941 to address nutrient needs during wartime rationing, and were later expanded in the 1990s to incorporate assessments of upper intake levels and additional reference points.[2] Their primary purposes include establishing nutrient intake goals for healthy populations, evaluating the adequacy of diets at both individual and group levels, and informing public health policies such as food labeling standards through derived Daily Values (DVs).[1][2] By considering factors like bioavailability, physiological requirements, and risk of deficiency or toxicity, DRIs support evidence-based nutrition recommendations across diverse life stages, from infancy to older adulthood.[2]Overview and Parameters
Definition and Purpose
Dietary Reference Intakes (DRIs) are a comprehensive set of evidence-based reference values for nutrient intakes, developed by the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine (NASEM) for healthy populations in the United States and Canada.[3] These values provide quantitative estimates to guide the planning and assessment of diets, varying by age, sex, and life stage.[1] DRIs encompass more than 40 nutrients and food substances, including vitamins, minerals, macronutrients such as carbohydrates, proteins, and fats, as well as electrolytes like sodium and potassium.[4] The primary purposes of DRIs are to evaluate nutrient adequacy in diets for individuals and groups, establish standards for nutrition labeling on food products, determine appropriate levels for food fortification, and support public health policies aimed at preventing nutrient deficiencies, excessive intakes, and diet-related chronic diseases.[3] By offering a framework for these applications, DRIs help nutrition professionals, policymakers, and consumers make informed decisions to promote optimal health outcomes.[5] DRIs are intended for healthy individuals and do not address therapeutic needs for those with medical conditions or diseases.[1] Their scope includes life stages from infancy (ages 0-12 months) through adolescence (up to 18 years), adulthood, pregnancy, and lactation, ensuring tailored recommendations across diverse populations.[3] Evolving from the earlier Recommended Dietary Allowances (RDAs) established since 1941, DRIs were introduced in the 1990s to expand beyond minimum requirements by incorporating upper limits and other intake metrics.[6] Key parameters such as the RDA and Tolerable Upper Intake Level (UL) form the core of this system.[1]Key Parameters
The Dietary Reference Intakes (DRIs) encompass several key parameters designed to guide nutrient intake across populations, each serving distinct purposes in assessing and planning diets. The Estimated Average Requirement (EAR) represents the average daily nutrient intake level estimated to meet the requirements of half (50%) of healthy individuals in a specific life stage and gender group, based on criteria of adequacy such as biochemical markers or functional outcomes.[1] It forms the foundation for deriving other parameters and is primarily used to evaluate the adequacy of nutrient intakes for groups, such as in population surveys, rather than individuals.[7] The Recommended Dietary Allowance (RDA) is the intake level that meets the nutrient needs of nearly all (97-98%) healthy individuals, calculated as the EAR plus two standard deviations (SD) of the requirement distribution, assuming a normal distribution:\text{RDA} = \text{EAR} + 2 \times (\text{SD of requirement})
where the SD is often approximately 10% of the EAR unless data indicate otherwise.[7] This parameter provides a goal for individual daily intake to prevent deficiency, and it is derived directly from the EAR when sufficient data on variability exist.[8] When insufficient evidence exists to establish an EAR and thus an RDA, the Adequate Intake (AI) is set instead, based on observed or experimentally determined approximations of nutrient intake by healthy groups that appear to maintain a defined nutritional state, such as median intakes in populations without signs of deficiency.[8] The AI serves as a provisional recommendation for individuals and groups, acting as a proxy for the RDA in data-limited scenarios.[3] To address potential risks from excess intake, the Tolerable Upper Intake Level (UL) defines the highest average daily nutrient amount likely to pose no risk of adverse health effects for almost all individuals in the general population, derived from data on toxicity thresholds or no-observed-adverse-effect levels.[7] It is used to guide against overconsumption, particularly from supplements or fortified foods, and is established independently of the EAR or RDA based on adverse effect evidence.[8] For macronutrients, the Acceptable Macronutrient Distribution Range (AMDR) specifies the percentage of total energy intake from carbohydrates (45-65%), total fat (20-35%), and protein (10-35%) that is associated with reduced risk of chronic disease while ensuring adequate intake of essential nutrients.[3] This range promotes balanced energy distribution and is applied in dietary planning to optimize health outcomes without focusing on absolute amounts.[7] These parameters are interrelated: the RDA builds on the EAR for sufficiency, while the AI substitutes when variability data are lacking; the UL complements them by addressing upper limits from separate risk data.[8] A newer addition, the Chronic Disease Risk Reduction (CDRR) intake, introduced in 2019 for nutrients like sodium and potassium, indicates levels above which reducing intake is expected to lower chronic disease risk in healthy populations, without an associated lower threshold.[9] DRIs also include adjustments for special life stages, such as pregnancy and lactation, where EARs, RDAs, AIs, and ULs are elevated to account for increased physiological demands like fetal growth or milk production.[7]
| Parameter | Definition | Primary Use |
|---|---|---|
| EAR | Intake meeting needs of 50% of healthy individuals | Assessing group adequacy |
| RDA | Intake meeting needs of 97-98% of healthy individuals (EAR + 2 SD) | Individual intake goals |
| AI | Approximate intake maintaining health when data insufficient for RDA/EAR | Provisional recommendations |
| UL | Maximum safe daily intake without adverse effects | Avoiding toxicity |
| AMDR | Energy percentage range for macronutrients reducing chronic disease risk | Balanced dietary planning |
| CDRR | Intake above which reduction lowers chronic disease risk | Risk reduction guidance (e.g., sodium >2,300 mg/day) |
History and Development
Origins
The foundations of the Dietary Reference Intakes (DRIs) lie in the early recognition of nutrient deficiencies and the need for standardized intake guidelines, beginning with 18th- and 19th-century observations of diet-related diseases. In 1747, Scottish naval surgeon James Lind conducted the first recorded controlled clinical trial aboard the HMS Salisbury, assigning scorbutic sailors to different dietary interventions and finding that citrus fruits, such as oranges and lemons, effectively prevented and cured scurvy, laying groundwork for understanding essential dietary factors beyond basic calories. Throughout the 19th century, further insights into deficiency diseases emerged, including the role of specific foods in preventing conditions like beriberi and rickets, which spurred biochemical investigations into "accessory food factors."[10] The early 20th century marked the scientific discovery of vitamins, pivotal to the eventual development of reference intakes. In 1913, biochemist Elmer V. McCollum and Marguerite Davis at the University of Wisconsin identified a fat-soluble growth-promoting factor in butter and egg yolk, distinct from water-soluble factors, which was later recognized as vitamin A and essential for vision and epithelial health.[11] Their work between 1913 and 1916 differentiated fat-soluble vitamins (A and later D) from water-soluble ones (B), establishing the concept of micronutrients required in trace amounts to prevent deficiencies and support growth, influencing global nutrition research.[12] These discoveries highlighted the inadequacy of calorie-focused diets alone, prompting institutional efforts to quantify needs. From the 1930s, the U.S. National Research Council (NRC) collaborated with Canadian nutrition experts, including the Canadian Council on Nutrition, to address emerging data on human requirements amid economic and health challenges.[13] This partnership culminated in the establishment of the Food and Nutrition Board (FNB) within the NRC in 1940. In response to World War II demands for efficient food rationing and to safeguard military and civilian health against deficiencies, the FNB issued the first Recommended Dietary Allowances (RDAs) report in 1941, providing minimum intake standards to maintain health under constrained supplies.[14] The report emphasized basal metabolic rates, physical activity levels, and growth requirements as the basis for these allowances, aiming to cover the needs of nearly all healthy individuals while preventing overt deficiencies.[15] The initial 1941 RDA scope covered ten key essentials: protein, calcium, iron, vitamins A, C, and D, thiamine, riboflavin, niacin, and energy (calories), selected for their proven roles in averting common wartime shortages like anemia and fatigue.[16][17] Subsequent revisions in 1943, 1945, and 1948 expanded and refined these, incorporating additional nutrients and adjusting values based on new metabolic data, while maintaining the focus on deficiency prevention for adults and children. These early RDAs, now evolved into DRIs, represented a shift from ad hoc dietary advice to evidence-based national standards.Major Milestones and Updates
The development of Dietary Reference Intakes (DRIs) built upon the earlier Recommended Dietary Allowances (RDAs) framework, with significant expansions in the late 1960s and 1970s to incorporate emerging nutritional science. The 1968 revision of the RDAs, the sixth edition published by the Food and Nutrition Board of the National Academy of Sciences, expanded coverage from nine to sixteen nutrients, introducing allowances for zinc, vitamin B6, vitamin E, and magnesium for the first time, reflecting growing recognition of their roles in human health.[16] This edition also emphasized considerations for nutrient bioavailability and dietary sources to better account for variations in absorption from food. The 1974 seventh edition further broadened the scope by adding folates, vitamin B12, biotin, and pantothenic acid, while refining values for existing nutrients based on updated evidence on bioavailability, such as adjustments for iron absorption influenced by dietary factors.[18] A paradigm shift occurred in the 1980s and 1990s, transitioning from deterministic RDAs to a more probabilistic and comprehensive DRI system that addressed both deficiencies and excesses. The 1989 tenth edition of the RDAs introduced a statistical approach, setting values to meet the needs of 97-98% of healthy individuals using variability in requirements, marking a departure from earlier fixed allowances.[19] In 1994, the Institute of Medicine (IOM, now part of the National Academy of Sciences, Engineering, and Medicine or NASEM) launched the DRI project in collaboration with Health Canada, culminating in the 1997 report on calcium, phosphorus, magnesium, vitamin D, and fluoride, which established new categories including Estimated Average Requirements (EAR), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL) for these five nutrients.[20][21] This expansion highlighted risks from nutrient excesses, such as vitamin A toxicity, and involved joint U.S.-Canada harmonization efforts that began in the mid-1990s, drawing on international experts through IOM panels.[22] The 2000s saw DRI reports extend to macronutrients and other essentials, with a growing focus on evidence-based strategies for risk reduction. The 2002 report on energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids set an AI for dietary fiber at 14 grams per 1,000 kilocalories to support cardiovascular health and gastrointestinal function. Subsequent reports in 2004 addressed water, electrolytes including sodium and potassium, and sulfate, emphasizing hydration and balance for overall health. In the 2010s, updates prioritized chronic disease prevention; the 2011 revision for calcium and vitamin D incorporated systematic evidence reviews, while the 2017 guiding principles allowed DRIs to consider endpoints like cardiovascular disease risk. The 2019 report introduced Chronic Disease Risk Reduction (CDRR) intakes, recommending sodium reduction to less than 2,300 mg per day to lower blood pressure and heart disease risk, alongside potassium AI increases.[20] Recent developments through 2025 have featured targeted revisions without a full DRI overhaul since 2011, aligning with public health priorities such as cardiovascular and metabolic health. The joint U.S.-Canada process, supported by NASEM since the IOM era, continues to involve expert panels with global input; for instance, omega-3 fatty acids were prioritized for review in 2014 but remain under ongoing evaluation as of 2025. In 2023, NASEM updated DRIs for energy, refining requirements based on physical activity levels and body composition to better prevent obesity-related risks.[20] These incremental updates underscore the evolving emphasis on chronic disease prevention through balanced nutrient intakes.Current Recommendations for United States and Canada
Vitamins and Choline
The Dietary Reference Intakes (DRIs) for vitamins and choline provide evidence-based guidelines to meet the nutritional needs of nearly all healthy individuals in the United States and Canada, distinguishing between Recommended Dietary Allowances (RDAs) for most vitamins—set to meet the needs of 97-98% of the population—and Adequate Intakes (AIs) where data are insufficient for RDAs, such as for choline and vitamin K.[23] These values account for bioavailability, with units like retinol activity equivalents (RAE) for vitamin A and dietary folate equivalents (DFE) for folate to reflect absorption differences from food versus supplements. Tolerable Upper Intake Levels (ULs) are established to prevent adverse effects, such as hypervitaminosis from excess fat-soluble vitamins. Fat-soluble vitamins—A, D, E, and K—are absorbed with dietary fats and stored in the body, requiring careful ULs to avoid toxicity. Vitamin A supports vision, immune function, and reproduction, with adult RDAs of 900 μg RAE for males and 700 μg RAE for females, and a UL of 3,000 μg RAE to prevent liver damage and birth defects. Vitamin D, crucial for calcium absorption and bone health, saw its RDA increased in the 2011 update to 15 μg (600 IU) daily for adults aged 19-70 years and 20 μg (800 IU) for those over 70, based on achieving serum 25-hydroxyvitamin D levels of at least 50 nmol/L to support bone mineralization without excess risk; the UL remains 100 μg (4,000 IU).[24] Vitamin E acts as an antioxidant protecting cell membranes, with an RDA of 15 mg alpha-tocopherol for adults and a UL of 1,000 mg to avoid bleeding risks from interfering with vitamin K. Vitamin K, essential for blood clotting and bone metabolism, uses AIs of 120 μg for adult males and 90 μg for females, with no UL due to lack of adverse effect data. The following table summarizes key DRI values for fat-soluble vitamins by selected life stages (values in μg/day for A and K, μg/day for D, mg/day for E; ND = not determinable due to insufficient data).[25]| Life Stage Group | Vitamin A (RDA) Males/Females | Vitamin D (RDA/AI) | Vitamin E (RDA) | Vitamin K (AI) Males/Females |
|---|---|---|---|---|
| Infants 0-6 mo (AI) | 400/400 | 10 | 4 | 2/2 |
| Infants 7-12 mo (AI) | 500/500 | 10 | 5 | 2.5/2.5 |
| Children 1-3 y (RDA) | 300/300 | 15 | 6 | 30/30 |
| Adults 19-50 y (RDA/AI) | 900/700 | 15 | 15 | 120/90 |
| Pregnancy 19-50 y | -/750 | 15 | 15 | -/90 |
| Lactation 19-50 y | -/1,300 | 15 | 19 | -/90 |
| UL (Adults 19+ y) | 3,000 | 100 | 1,000 | ND |
| Life Stage Group | Thiamin (RDA) Males/Females | Vitamin C (RDA) Males/Females | Folate (RDA, μg DFE) | Vitamin B12 (RDA, μg) |
|---|---|---|---|---|
| Infants 0-6 mo (AI) | 0.2/0.2 | 40/40 | 65 | 0.4 |
| Children 1-3 y (RDA) | 0.5/0.5 | 15/15 | 150 | 0.9 |
| Adults 19-50 y (RDA) | 1.2/1.1 | 90/75 | 400 | 2.4 |
| Pregnancy 19-50 y | -/1.4 | -/85 | 600 | 2.6 |
| Lactation 19-50 y | -/1.4 | -/120 | 500 | 2.8 |
| UL (Adults 19+ y) | ND | 2,000 | 1,000 (synthetic) | ND |
| Life Stage Group | Choline (AI, mg/day) Males/Females | UL (mg/day) |
|---|---|---|
| Infants 0-6 mo | 125/125 | ND |
| Children 1-3 y | 200/200 | 1,000 |
| Adults 19-50 y | 550/425 | 3,500 |
| Pregnancy 19-50 y | -/450 | 3,500 |
| Lactation 19-50 y | -/550 | 3,500 |
Minerals
Minerals encompass a diverse group of inorganic elements essential for structural integrity, enzymatic reactions, metabolic regulation, and electrolyte balance in the human body. The Dietary Reference Intakes (DRIs) for minerals, established by the National Academies of Sciences, Engineering, and Medicine (NASEM), vary by life stage, sex, and physiological needs, reflecting differences in absorption efficiency, dietary sources, and health risks from deficiency or excess. These values include Recommended Dietary Allowances (RDAs) where data allow estimation of requirements for nearly all individuals, Adequate Intakes (AIs) based on observed intakes in healthy populations, and Tolerable Upper Intake Levels (ULs) to prevent adverse effects. Variability arises from factors like bioavailability, which can be influenced by dietary inhibitors or enhancers, and specific demands during growth, pregnancy, or aging.[29] Macrominerals, required in larger amounts, play key roles in skeletal health and acid-base balance. Calcium supports bone mineralization, muscle contraction, and nerve signaling, with absorption enhanced by vitamin D. The RDA for adults aged 19-50 years is 1,000 mg/day, increasing to 1,200 mg/day for women aged 51 years and older and men aged 71 years and older to counteract age-related bone loss; the UL is 2,500 mg/day for adults 19-50 years to avoid risks like kidney stones. Phosphorus, integral to bone structure and energy metabolism via ATP, has an RDA of 700 mg/day for adults 19 years and older, with a UL of 4,000 mg/day to prevent calcification of soft tissues. Magnesium contributes to over 300 enzymatic reactions, including DNA synthesis and glucose control; RDAs range from 310-320 mg/day for adult women to 400-420 mg/day for adult men, with a UL of 350 mg/day from non-food sources due to risks of diarrhea and hypotension. For infants, the AI for calcium is 200 mg/day for ages 0-6 months, reflecting rapid skeletal growth.[24][30][31]| Life Stage Group | Calcium (mg/day) | Phosphorus (mg/day) | Magnesium (mg/day) | |||
|---|---|---|---|---|---|---|
| RDA | UL | RDA | UL | RDA | UL (supplements only) | |
| Adults 19-30 y (M) | 1,000 | 2,500 | 700 | 4,000 | 400 | 350 |
| Adults 19-30 y (F) | 1,000 | 2,500 | 700 | 4,000 | 310 | 350 |
| Adults 31-50 y (M) | 1,000 | 2,500 | 700 | 4,000 | 420 | 350 |
| Adults 31-50 y (F) | 1,000 | 2,500 | 700 | 4,000 | 320 | 350 |
| Adults 51-70 y (M) | 1,000 | 2,000 | 700 | 4,000 | 420 | 350 |
| Adults 51-70 y (F) | 1,200 | 2,000 | 700 | 4,000 | 320 | 350 |
| Adults 71+ y (M/F) | 1,200 | 2,000 | 700 | 3,000 | 420 (M), 320 (F) | 350 |
| Life Stage Group | Iron (mg/day) | Zinc (mg/day) | Iodine (μg/day) | Selenium (μg/day) | ||||
|---|---|---|---|---|---|---|---|---|
| RDA | UL | RDA | UL | RDA | UL | RDA | UL | |
| Adults 19-50 y (M) | 8 | 45 | 11 | 40 | 150 | 1,100 | 55 | 400 |
| Adults 19-50 y (F) | 18 | 45 | 8 | 40 | 150 | 1,100 | 55 | 400 |
| Adults 51+ y (M/F) | 8 | 45 | 11 (M), 8 (F) | 40 | 150 | 1,100 | 55 | 400 |
| Pregnancy (19-50 y) | 27 | 45 | 11-12 | 40 | 220 | 1,100 | 60 | 400 |
Macronutrients
The Dietary Reference Intakes (DRIs) for macronutrients establish quantitative goals for carbohydrates, protein, total fat, dietary fiber, and water to support energy needs, metabolic functions, and health in healthy populations across the United States and Canada. These values, developed through systematic evidence reviews, include Recommended Dietary Allowances (RDAs) where data allow estimation of requirements for nearly all individuals, Adequate Intakes (AIs) based on observed intakes in healthy groups, and Acceptable Macronutrient Distribution Ranges (AMDRs) to balance energy sources while minimizing chronic disease risk. Emphasis is placed on macronutrient quality, such as prioritizing whole foods over refined sources, to enhance nutrient density and long-term health outcomes. For carbohydrates, the primary energy source, the RDA is set at 130 g/day for adults and children aged 1 year and older, reflecting the minimum amount required to fuel brain glucose oxidation under normal conditions. The AMDR for carbohydrates is 45–65% of total daily energy intake, providing flexibility to accommodate varied dietary patterns while ensuring adequate energy and preventing excessive fat or protein displacement. The 2002 component of the macronutrient report underscores carbohydrate quality, advising limitation of added sugars—defined as sugars and syrups added to foods during processing or preparation—to no more than 25% of total energy intake to permit consumption of nutrient-dense foods that meet other DRI requirements. Protein recommendations focus on maintaining nitrogen balance and supporting tissue repair, with the RDA for adults aged 19 years and older calculated as 0.8 g per kg of body weight per day. This equates to approximately 46 g/day for adult women (using a reference weight of 57 kg) and 56 g/day for adult men (using 70 kg), though individual needs vary with body size. During pregnancy, the RDA increases to 1.1 g/kg/day to accommodate maternal and fetal demands. The AMDR for protein is 10–35% of total energy, allowing adaptation to diverse diets without risking deficiencies or excesses. The protein RDA is determined using the equation: \text{RDA (g/day)} = 0.8 \times \text{body weight (kg)} This formula adjusts for lean body mass but assumes average composition; for those consuming primarily plant-based proteins, which often have lower digestibility and incomplete amino acid profiles, the 2005 report recommends intakes 10–20% above the RDA to ensure adequacy. Total fat lacks an RDA due to variable needs beyond essential fatty acids, but the AMDR is 20–35% of total energy to support cell membrane integrity and hormone production while limiting chronic disease risk. AIs are established for polyunsaturated fatty acids: linoleic acid (an omega-6 fatty acid) at 17 g/day for men aged 19–30 years and 12 g/day for women in the same age group, and alpha-linolenic acid (an omega-3) at 1.6 g/day for men and 1.1 g/day for women, based on preventing deficiency symptoms and maintaining plasma levels. These values prioritize sources like vegetable oils and nuts to promote cardiovascular health without setting upper limits for total saturated or trans fats beyond general moderation. Dietary fiber, an indigestible carbohydrate component, has an AI of 14 g per 1,000 kcal of energy intake, corresponding to 25 g/day for adult women and 38 g/day for adult men to support gastrointestinal health and reduce risks of coronary heart disease and diabetes. No Tolerable Upper Intake Level (UL) is defined for fiber from natural food sources, as adverse effects like mineral absorption interference are not consistently observed at high intakes from whole foods. Water, essential for hydration and physiological processes, has an AI of 3.7 L/day (including 0.8 L from food) for adult men and 2.7 L/day (0.7 L from food) for adult women, derived from balance studies in temperate climates. No RDA or UL is established, as requirements fluctuate with physical activity, climate, and diet, but the 2004 electrolytes report links increased needs to exercise-induced losses, recommending adjustments up to 1.5–2 times basal levels during prolonged activity. The following table summarizes key DRI values for macronutrients in adults (ages 19–50 years, non-pregnant/lactating unless noted):| Macronutrient | Parameter | Value (Adults 19–50 Years) | Basis/Notes |
|---|---|---|---|
| Carbohydrates | RDA | 130 g/day | Minimum for brain glucose needs; applies to ages 1+ |
| AMDR | 45–65% of energy | Balances energy with other macros | |
| Protein | RDA | 0.8 g/kg body weight/day (e.g., 46 g women, 56 g men) | Nitrogen balance; pregnancy: 1.1 g/kg/day |
| AMDR | 10–35% of energy | Supports varied diets; higher for plant-based sources | |
| Total Fat | AMDR | 20–35% of energy | No RDA; focuses on essential fats |
| Linoleic Acid (ω-6) | AI | 17 g/day (men), 12 g/day (women) | Prevents deficiency; from plant oils |
| α-Linolenic Acid (ω-3) | AI | 1.6 g/day (men), 1.1 g/day (women) | Supports membrane function; ratio to ω-6 ~1:4 recommended |
| Dietary Fiber | AI | 14 g/1,000 kcal (25 g/day women, 38 g/day men) | Gut health; no UL for food sources |
| Total Water | AI | 3.7 L/day (men), 2.7 L/day (women) | Includes food/beverages; increases with activity |