Histidine
What it is and what it does
- Histidine is one of the nine essential amino acids, along with the others listed by MedlinePlus. (MedlinePlus Medical Encyclopedia (US National Library of Medicine): Amino acids (review date 1/21/2025))
- Histidine was once thought to be non-essential, because a diet lacking it does not quickly upset the body's protein balance the way a lack of other essential amino acids does. (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
- It is now counted as an essential (indispensable) amino acid because diets without histidine have been seen to harm haemoglobin levels. (WHO/FAO/UNU (2007). Protein and amino acid requirements in human nutrition: report of a joint FAO/WHO/UNU expert consultation. WHO Technical Report Series 935)
- The body makes histamine from histidine, using the enzyme histidine decarboxylase. (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
- Histidine holds the iron in haemoglobin and myoglobin, and is often found at the working (active) sites of metal-containing enzymes. (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
- Among the amino acids in proteins, only histidine's side chain (the imidazole ring) is suited to act as a pH buffer. (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
- Histidine is part of carnosine, a dipeptide found in large amounts in skeletal muscle. (WHO/FAO/UNU (2007). Protein and amino acid requirements in human nutrition: report of a joint FAO/WHO/UNU expert consultation. WHO Technical Report Series 935)
Why it matters
- When people ate a histidine-deficient diet for a long period, their haemoglobin fell while serum iron rose. (WHO/FAO/UNU (2007). Protein and amino acid requirements in human nutrition: report of a joint FAO/WHO/UNU expert consultation. WHO Technical Report Series 935)
- An eczema-like skin rash has been seen in infants and adults fed a diet lacking histidine. (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
- On higher intakes (as supplements), a 2020 review reports a consensus among researchers that increased histidine intake is safe ... (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
General information, not medical advice — for your own needs, ask a doctor or dietitian.
How much is needed
| Who | Amount | What the figure is | Whose figure |
|---|---|---|---|
| Adults | 15 mg per g protein | Recommended amino acid pattern (ICMR-NIN 2020) | ICMR-NIN 2020 (as printed in DGI 2024 Table 8.2) |
| Adults (mean requirement) | 10 mg/kg body weight/day | Average requirement | FAO/WHO/UNU 2007 (not an Indian value) |
| Older children, adolescents and adults | 16 mg per g protein | Scoring pattern for protein quality | FAO 2013 (not an Indian value) |
India’s own figure (ICMR-NIN 2020) comes first. Figures from other bodies are shown only where they help, and say whose they are.
Sources: ICMR-NIN. Dietary Guidelines for Indians 2024; WHO/FAO/UNU (2007). Protein and amino acid requirements in human nutrition: report of a joint FAO/WHO/UNU expert consultation. WHO Technical Report Series 935; FAO (2013). Dietary protein quality evaluation in human nutrition: report of an FAO Expert Consultation. FAO Food and Nutrition Paper 92
In every millet and pseudo-cereal, per 100 g raw
| Grain | Amount | Source |
|---|---|---|
| Quinoa | 2.98 g per 100 g protein | IFCT A009 |
| Ragi (finger millet) | 2.37 g per 100 g protein | IFCT A010 |
| Little millet | 2.35 g per 100 g protein | IFCT A016 |
| Bajra (pearl millet) | 2.15 g per 100 g protein | IFCT A003 |
| Kodo millet | 2.14 g per 100 g protein | IFCT A017 |
| Jowar (sorghum) | 2.07 g per 100 g protein | IFCT A005 |
| Rajgira (amaranth) | 1.98 g per 100 g protein | IFCT A002 |
| Kuttu (buckwheat) | 0.309 g | USDA FDC 170286 |
| Teff | 0.301 g | USDA FDC 169747 |
| Proso millet | 0.236 g | USDA FDC 169702 |
Each grain has ONE source, named on its page: IFCT = Indian Food Composition Tables 2017 (ICMR-NIN) with its food code; USDA FDC; FAO WAFCT 2019; NIN 2007 via ICAR-IIMR. Values exactly as printed, not converted — tables differ in method, so compare within a source. Published values for the grain, not a laboratory test of our packs.
Absorption and food
- Plant proteins such as soybean, kidney beans, peas, oats and wheat contain about 20-30 mg histidine per gram of protein. (Holecek M. Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement. Nutrients 2020;12(3):848. doi:10.3390/nu12030848 (open access, CC BY))
- ICMR-NIN's model vegetarian diet ('My Plate for the Day') provides 24.1 mg histidine per g of protein, more than the 15 mg/g recommendation. (ICMR-NIN. Dietary Guidelines for Indians 2024)