Personalized Nutrition Recommender

This tool combines two independent reference systems. The energy layer estimates basal metabolic rate from the Mifflin-St Jeor equation, scales it by a physical activity level between 1.2 and 1.9, and applies a goal offset. Protein is then prescribed per kilogram of body mass rather than as a percentage of energy, because protein requirements track lean tissue and not calorie intake: 1.0 g/kg for general health, 1.4 g/kg during a deficit to protect lean mass, and 1.8 g/kg for hypertrophy or performance. Fat takes 30 percent of energy and carbohydrate fills the remainder. The micronutrient layer reports Dietary Reference Intake values that vary by life stage - iron at 18 mg for women aged 19 to 50 against 8 mg otherwise, calcium rising from 1,000 to 1,200 mg with age, vitamin D from 600 to 800 IU after 70, and B12 at 2.4 micrograms. Those reference values are population statistics, not personal targets. An RDA is set to cover 97 to 98 percent of healthy people in a group, so it deliberately exceeds the average requirement and following it precisely is not a deficiency test. Tolerable Upper Intake Levels matter once supplements enter the picture, with iron at 45 mg, zinc at 40 mg, and vitamin D at 4,000 IU for adults. Bioavailability complicates matters further: non-heme iron from plants absorbs at roughly 2 to 20 percent against 15 to 35 percent for heme iron, which is why vitamin C pairing is suggested. Pregnancy, lactation, kidney disease, and malabsorption fall outside this framework.

Formal nutrient recommendations began as wartime policy. In 1941 the Food and Nutrition Board of the United States National Research Council, tasked with planning military rations and civilian food supply, issued the first Recommended Dietary Allowances, covering calories and a short list of vitamins and minerals. The RDAs were revised roughly every five years thereafter, reaching a tenth edition in 1989. Their purpose was narrow - preventing classical deficiency diseases such as scurvy, beriberi, and rickets across populations - and they were never designed as individual prescriptions, a distinction that has been widely misread ever since. Beginning in 1997 the Institute of Medicine replaced them with the Dietary Reference Intakes, a four-value framework of Estimated Average Requirement, Recommended Dietary Allowance, Adequate Intake where evidence is insufficient to set an RDA, and Tolerable Upper Intake Level. The reports were issued nutrient group by nutrient group through 2005, with calcium and vitamin D revised in 2011 and sodium and potassium in 2019 under the National Academies. Vitamin B12, the nutrient that most sharply separates plant-based diets from others, was isolated in 1948 by teams under Karl Folkers in the United States and E. Lester Smith in Britain, and Dorothy Hodgkin resolved its structure by X-ray crystallography in 1956. The Academy of Nutrition and Dietetics position paper of 2016 affirms well-planned vegetarian and vegan diets as adequate while flagging B12 supplementation as necessary.