Nutrients

NutrientAPI returns 14 nutrients for every recipe analysis. These cover the nutrients required on US FDA Nutrition Facts labels, giving you everything needed to generate compliant labels or power nutrition-tracking features.

All nutrient values are calculated deterministically from USDA FoodData Central data. The AI component handles only natural language parsing and food matching; once a food is identified, the math is straightforward multiplication from USDA's per-100g values.

Quick Reference

Field Name	Unit	Category
calories	kcal	Energy
protein	g	Macronutrient
fat_total	g	Macronutrient
fat_saturated	g	Fat breakdown
fat_trans	g	Fat breakdown
cholesterol	mg	Fat-related
sodium	mg	Mineral
carbs_total	g	Macronutrient
carbs_sugar	g	Carb breakdown
carbs_fiber	g	Carb breakdown
vitamin_d	mcg	Vitamin
calcium	mg	Mineral
iron	mg	Mineral
potassium	mg	Mineral

Detailed Nutrient Descriptions

Energy

calories — kilocalories (kcal)

The total metabolizable energy in the food, measured in kilocalories. This is what most people mean when they say "calories." It represents the energy your body can extract from the food through digestion. The USDA derives this value using the Atwater system, which assigns energy factors to protein (4 kcal/g), fat (9 kcal/g), and carbohydrate (4 kcal/g), with adjustments for specific food types where more precise factors are known.

Macronutrients

protein — grams (g)

Total protein content, determined from the nitrogen content of the food using the Kjeldahl method. Protein provides 4 kcal per gram and is essential for muscle maintenance, immune function, and enzyme production. This value includes all amino acids from both complete proteins (meat, dairy, eggs) and incomplete proteins (grains, legumes).

fat_total — grams (g)

Total lipid (fat) content, including saturated, monounsaturated, polyunsaturated, and trans fats. Fat provides 9 kcal per gram, making it the most energy-dense macronutrient. This value encompasses all fatty acids regardless of chain length or saturation.

carbs_total — grams (g)

Total carbohydrate content, calculated by difference: the weight remaining after subtracting water, protein, fat, ash, and alcohol from the total food weight. This includes sugars, starches, and dietary fiber. Digestible carbohydrates provide 4 kcal per gram.

Fat Breakdown

fat_saturated — grams (g)

Saturated fatty acids. These fats have no double bonds in their carbon chains, making them solid at room temperature. Found predominantly in animal products (butter, cheese, fatty meat) and some plant oils (coconut, palm). The FDA Daily Value is less than 20g for a 2,000-calorie diet.

fat_trans — grams (g)

Trans fatty acids, including both naturally occurring trans fats (found in small amounts in dairy and meat from ruminant animals) and industrially produced trans fats (from partial hydrogenation of vegetable oils). The FDA requires declaration of trans fat on Nutrition Facts labels when present at 0.5g or more per serving.

cholesterol — milligrams (mg)

Dietary cholesterol, a waxy lipid found only in animal-derived foods. Eggs, organ meats, and shellfish are among the richest sources. Plant-based foods contain zero cholesterol. The FDA's reference Daily Value is 300mg.

Carbohydrate Breakdown

carbs_sugar — grams (g)

Total sugars, including both naturally occurring sugars (fructose in fruit, lactose in milk) and added sugars. This value represents all mono- and disaccharides present in the food. The API does not currently distinguish between natural and added sugars.

carbs_fiber — grams (g)

Dietary fiber, the indigestible portion of plant-based carbohydrates. Includes both soluble fiber (which dissolves in water and can lower cholesterol) and insoluble fiber (which aids digestion). Fiber is subtracted from total carbohydrates when calculating "net carbs." The FDA Daily Value is 28g.

Minerals

sodium — milligrams (mg)

Sodium, an essential mineral that regulates fluid balance and nerve function. Most dietary sodium comes from salt (sodium chloride) added during food processing or cooking. The FDA Daily Value is 2,300mg. This is one of the most important nutrients for nutrition labeling and health-tracking applications.

calcium — milligrams (mg)

Calcium, essential for bone health, muscle contraction, and nerve signaling. Major dietary sources include dairy products, fortified plant milks, leafy greens, and canned fish with bones. The FDA Daily Value is 1,300mg.

iron — milligrams (mg)

Iron, necessary for oxygen transport in the blood (as part of hemoglobin) and energy metabolism. Exists in two dietary forms: heme iron (from animal sources, more easily absorbed) and non-heme iron (from plant sources). The FDA Daily Value is 18mg.

potassium — milligrams (mg)

Potassium, critical for heart rhythm, muscle contraction, and maintaining normal blood pressure. Rich sources include bananas, potatoes, beans, and yogurt. The FDA Daily Value is 4,700mg. Potassium was added to the mandatory Nutrition Facts label in 2020.

Vitamins

vitamin_d — micrograms (mcg)

Vitamin D, a fat-soluble vitamin essential for calcium absorption and bone health. Few foods are naturally rich in vitamin D; fatty fish and egg yolks are among the best sources. Many foods (milk, cereals, orange juice) are fortified with it. The FDA Daily Value is 20mcg. Vitamin D was added as a mandatory Nutrition Facts label nutrient in 2020.

Response Structure

Nutrients appear in three places in the API response:

{
  "ingredients": [
    {
      "input": "2 cups chopped romaine lettuce",
      "nutrients": {
        "calories": 16.0,
        "protein": 1.2,
        // ... all 14 nutrients for this ingredient
      }
    }
  ],
  "total_nutrients": {
    "calories": 385.0,
    // ... summed across all ingredients
  },
  "per_serving": {
    "calories": 192.5,
    // ... total divided by servings count
  }
}

• ingredients[].nutrients — Nutrients for each individual ingredient
• total_nutrients — Sum of all ingredient nutrients (the whole recipe)
• per_serving — Total nutrients divided by the servings value you provide

Data Source

All nutrient values come from the USDA FoodData Central database. NutrientAPI indexes data from four USDA datasets:

• SR Legacy — The classic USDA food composition database with broad coverage of common foods
• Foundation Foods — Analytically measured values for minimally processed foods
• FNDDS — Survey data covering foods as consumed, including mixed dishes and prepared foods
• Branded Foods — Manufacturer-reported data for branded and packaged products

The database contains approximately 2 million food items. When matching ingredients, the system prioritizes SR Legacy and Foundation foods for common ingredients, as these have the most analytically rigorous nutrient data.

Precision and Rounding

Nutrient values are returned as floating-point numbers with up to one decimal place of precision. Values are not rounded to FDA label rounding rules; if you need to generate a compliant Nutrition Facts label, apply FDA rounding guidelines on your end.