Amaranth Leaves (Amaranthus cruentus)

Amaranth leaves (Amaranthus cruentus) are rich in dietary nitrates, which the body converts to nitric oxide via the nitrate-nitrite-NO pathway, supporting vascular tone and blood flow. Emerging evidence also points to neuroactive compounds in the leaf that may modulate cholinergic activity, producing memory-enhancing effects in preclinical models.

Origin & History

Amaranth leaves are the aerial parts of Amaranthus cruentus, a plant species in the Amaranthaceae family native to Central and South America. The leaves are typically harvested fresh, air-dried, and ground into powder or prepared as aqueous extracts by dissolving the dried material in boiled distilled water. Chemically, amaranth leaves belong to the class of polyphenol-rich plant materials with significant antioxidant compounds.

Historical & Cultural Context

The search results provided do not contain information on historical use in traditional medicine systems or the duration of traditional use. The plant is native to Central and South America but specific cultural applications were not documented in the available research.

Health Benefits

• Vascular health support: A human pharmacokinetic study (PMID: 27131407) demonstrated increased nitric oxide metabolites lasting at least 8 hours after consumption (preliminary human evidence)
• Cognitive enhancement potential: Animal studies showed memory-enhancing effects comparable to donepezil at 200-400 mg/kg doses (preliminary animal evidence)
• Reproductive health protection: Rat studies found 300 mg/kg aqueous extract ameliorated testicular damage and improved sperm parameters over 6 weeks (preliminary animal evidence)
• Anticancer properties: Cell culture studies showed 43-45% growth inhibition of cancer cells at 100 μg/ml through mitochondria-mediated apoptosis (preliminary in-vitro evidence)
• Antioxidant activity: Contains abundant polyphenols that scavenge free radicals as measured by DPPH radical assays (preliminary in-vitro evidence)

How It Works

Dietary nitrates in Amaranthus cruentus are reduced to nitrite by oral commensal bacteria and subsequently converted to nitric oxide (NO) by xanthine oxidoreductase and other enzymatic pathways under physiological conditions, causing smooth muscle relaxation and vasodilation via soluble guanylate cyclase activation and cyclic GMP elevation. In animal models, bioactive polyphenols and peptide fractions in amaranth leaves appear to inhibit acetylcholinesterase activity, increasing synaptic acetylcholine availability in hippocampal circuits linked to memory consolidation. Additionally, the leaves' high flavonoid content, including rutin and quercetin, may reduce oxidative stress by scavenging reactive oxygen species and upregulating Nrf2-mediated antioxidant gene expression.

Scientific Research

Human clinical evidence for amaranth leaves is limited to one pharmacokinetic study (PMID: 27131407) showing increased nitric oxide metabolites after a single oral dose. Most evidence comes from animal studies including testicular protection in rats (PMCID: PMC9355442) and cognitive enhancement in mice, with no published meta-analyses or large-scale human RCTs identified.

Clinical Summary

A human pharmacokinetic study (PMID: 27131407) demonstrated that consumption of Amaranthus cruentus leaves produced a statistically significant elevation in plasma nitric oxide metabolites (nitrate and nitrite) that persisted for at least 8 hours post-ingestion, providing preliminary human evidence for sustained vascular NO support. The study was limited in sample size and duration, meaning effect magnitude on blood pressure endpoints has not been rigorously quantified in humans. Memory-enhancing effects comparable to the cholinesterase inhibitor donepezil have been observed in rodent models, but no controlled human trials have yet confirmed cognitive outcomes. Overall, the evidence base is preliminary; larger randomized controlled trials are needed before clinical recommendations can be made.

Nutritional Profile

Per 100 g raw amaranth leaves (Amaranthus cruentus): Energy ~23 kcal; Protein ~2.5–3.5 g (notable for a leafy green, contains all essential amino acids including lysine at ~0.3 g); Fat ~0.3–0.5 g; Carbohydrates ~3.0–4.0 g; Dietary fiber ~2.0–2.2 g (mostly insoluble). MINERALS: Calcium ~215–270 mg (bioavailability moderate, ~20–30%, reduced by oxalate content of ~1.1–1.5 g/100 g); Iron ~2.3–3.0 mg (non-heme, bioavailability ~5–12%, enhanced by co-consumption with vitamin C); Magnesium ~55–75 mg; Potassium ~611–700 mg; Phosphorus ~50–65 mg; Zinc ~0.9–1.1 mg; Manganese ~0.85–1.0 mg; Copper ~0.16 mg. VITAMINS: Vitamin A (as beta-carotene) ~5,700–5,900 µg RAE equivalents from total carotenoids (~2,770 µg retinol activity); Vitamin C ~43–50 mg (significant source, but heat-labile—blanching reduces by ~40–60%); Folate (B9) ~85–90 µg; Riboflavin (B2) ~0.16–0.22 mg; Niacin (B3) ~0.7–0.9 mg; Vitamin B6 ~0.19–0.22 mg; Vitamin K ~1,140 µg (exceptionally high, one of the richest leafy green sources). BIOACTIVE COMPOUNDS: Betalains (amaranthine, isoamaranthine) ~50–120 mg/100 g fresh weight (potent antioxidants with ORAC values comparable to beets); Polyphenols (total) ~1.5–3.5 mg GAE/g dry weight, including rutin (~15–45 mg/100 g DW), quercetin glycosides, kaempferol, and gallic acid; Nitrate content ~2,000–4,800 mg/kg fresh weight (relevant to nitric oxide pathway and vascular effects noted in PMID: 27131407); Saponins ~0.1–0.3% DW; Phytosterols including beta-sitosterol and stigmasterol (~20–35 mg/100 g DW); Chlorophyll ~80–120 mg/100 g fresh weight; Lutein + zeaxanthin ~1,500–2,500 µg/100 g. ANTI-NUTRITIONAL FACTORS: Oxalates ~1.1–1.5 g/100 g (blanching/boiling reduces by 30–50%, significantly impacts calcium and iron bioavailability); Phytates ~0.2–0.5% DW (chelates zinc and iron); Tannins ~0.05–0.12% DW. BIOAVAILABILITY NOTES: Cooking (especially boiling 5–7 min) substantially reduces oxalate and improves mineral bioavailability but decreases vitamin C by ~40–60% and folate by ~20–30%; fat-soluble carotenoids and vitamin K absorption improved when consumed with dietary fat (~5–10 g); betalain pigments are water-soluble and partially heat-stable (60–70% retained after moderate cooking); high vitamin C content in raw leaves enhances non-heme iron absorption when consumed fresh; protein digestibility is high (~78–85%) compared to many leafy greens.

Preparation & Dosage

Animal studies used aqueous leaf extract at 200-400 mg/kg body weight for cognitive effects and 300 mg/kg for reproductive health, but human dosing has not been established. One human study used a single oral dose of amaranth extract (specific dose not detailed). No standardized extract or established human dosage ranges have been identified. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Other dark leafy greens, nitric oxide precursors, polyphenol-rich foods, antioxidant vitamins

Safety & Interactions

Amaranth leaves are generally recognized as safe when consumed as a food in culinary amounts, but concentrated supplemental doses have not been formally evaluated in long-term human safety studies. Because of their high nitrate content, individuals taking phosphodiesterase-5 inhibitors (e.g., sildenafil) or organic nitrate medications should exercise caution, as additive vasodilatory effects could cause hypotension. Amaranth leaves contain moderate levels of oxalates, which may increase kidney stone risk in individuals with a history of calcium oxalate nephrolithiasis or impaired renal function. Safety during pregnancy and lactation has not been established beyond normal dietary consumption, and high-dose supplemental use should be avoided until more data are available.