Purple Amaranth (Amaranthus cruentus)

Purple amaranth (Amaranthus cruentus) is a dark leafy green rich in betalains, flavonoids, and rutin, which exert antioxidant and anti-inflammatory effects primarily by scavenging reactive oxygen species and modulating NF-κB signaling. Its phytochemical profile has shown preliminary promise in supporting vascular tone and inhibiting cancer cell proliferation in early laboratory studies.

Origin & History

Purple amaranth (Amaranthus cruentus) is a nutrient-dense annual plant native to Central and South America, cultivated as a grain, leafy vegetable, and ornamental crop. It is sourced from seeds, leaves, or whole plant, with extracts typically prepared via solvent extraction methods for bioactive compounds. The plant belongs to the Amaranthaceae family and is rich in flavonoids, peptides, and amino acids.

Historical & Cultural Context

Amaranth species, including A. cruentus, have been used for millennia in Mesoamerican (Aztec/Maya) and African traditional systems as nutrient-rich grains and leafy greens for malnutrition, inflammation, and circulatory issues. Historical records note its role in staple foods and remedies for wounds, hypertension, and digestive ailments.

Health Benefits

• Supports vascular health by reducing inflammation and restoring vasal tone (in vitro evidence only)
• May protect against cellular damage through antioxidant activity and apoptosis reduction (preliminary in vitro data)
• Potentially inhibits cancer cell growth by 43-45% at tested extract doses (in vitro studies only)
• May support cardiovascular function through antithrombotic properties via rutin content (theoretical, no human studies)
• Could help maintain healthy blood pressure through encrypted amino acid sequences with antihypertensive effects (mechanism-based evidence only)

How It Works

Purple amaranth's primary bioactives — rutin, quercetin, and betalain pigments — inhibit NF-κB pathway activation, reducing downstream expression of pro-inflammatory cytokines such as TNF-α and IL-6 to support vascular tone restoration. Rutin and quercetin also directly scavenge superoxide and hydroxyl radicals, reducing lipid peroxidation and protecting cellular membranes from oxidative damage. Additionally, amaranth leaf extracts appear to modulate mitochondrial apoptotic pathways, potentially downregulating Bcl-2 expression and upregulating caspase-3 activity, which may explain the observed inhibition of cancer cell proliferation in vitro.

Scientific Research

No human clinical trials, RCTs, or meta-analyses specifically on Amaranthus cruentus were identified. Available data are limited to in vitro studies using 3D intestinal barrier and venous insufficiency models, which showed reduced inflammation and improved vascular parameters (p < 0.0001). References to AMARANTH trials (PMIDs: 31764959, 40675957) pertain to unrelated Alzheimer's drug studies, not the plant.

Clinical Summary

Current evidence for purple amaranth is limited to in vitro cell culture studies, with no published randomized controlled trials in humans as of early 2025. Laboratory experiments using amaranth leaf extracts demonstrated approximately 43–45% inhibition of cancer cell growth at tested concentrations, though the specific cell lines and extract doses vary across experiments. In vitro vascular models showed restoration of vasal tone and reduced endothelial inflammation markers, but these findings have not been replicated in animal models or human trials. The overall evidence base must be characterized as preliminary, and extrapolating these results to clinical outcomes in humans is not currently supported by the data.

Nutritional Profile

Per 100 g of raw leaves: Protein 3.5–4.5 g (notably high for a leafy green, rich in lysine); Carbohydrates 4–6 g; Dietary fiber 2.0–2.5 g; Fat 0.3–0.5 g; Energy ~23–30 kcal. Minerals: Iron 2.3–3.0 mg (non-heme; bioavailability enhanced by concurrent vitamin C intake), Calcium 215–270 mg (moderate bioavailability, partially reduced by oxalate content ~1.0–1.5 g/100 g), Magnesium 55–65 mg, Potassium 600–700 mg, Phosphorus 65–75 mg, Zinc 0.9–1.1 mg, Manganese 0.9–1.2 mg. Vitamins: Vitamin C 40–55 mg, Vitamin A (as β-carotene) 5,000–5,700 IU (~1,700–1,900 µg RAE; fat-soluble, bioavailability improved with dietary lipids), Folate (B9) 80–90 µg, Riboflavin (B2) 0.16–0.22 mg, Niacin (B3) 0.7–0.9 mg, Vitamin B6 0.19–0.24 mg, Vitamin K ~400–450 µg (phylloquinone). Bioactive compounds: Amaranthine and isoamaranthine (betalain pigments, 50–150 mg/100 g dry weight, responsible for red-purple coloration, potent water-soluble antioxidants), total phenolics 1.5–3.5 mg GAE/g fresh weight (including rutin 15–45 mg/100 g dry weight, quercetin glycosides, kaempferol derivatives), hydroxycinnamates (ferulic acid, p-coumaric acid), betacyanins contributing to ORAC values of 1,500–2,500 µmol TE/100 g fresh weight. Contains squalene in trace amounts in leaves (more concentrated in seeds, up to 5–8% of seed oil). Antinutritional factors include oxalates (1.0–1.5 g/100 g, reduced ~40–50% by blanching/boiling) and nitrates (variable, 1,000–4,000 mg/kg depending on soil nitrogen); phytate content is relatively low compared to seeds. Amino acid profile is well-balanced for a plant source, with lysine content (~5–6% of protein) notably higher than most cereals.

Preparation & Dosage

No clinically studied human dosages exist. In vitro models used 50 mg amaranthus extract (unstandardized) combined with other ingredients every 12 hours. Traditional food use involves dietary consumption of seeds and leaves. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Pumpkin seed extract, Hypersmin, Rutin, Vitamin C, Bilberry extract

Safety & Interactions

Purple amaranth consumed as a whole food is generally regarded as safe for most adults, but concentrated extracts and supplements lack long-term human safety data. Individuals taking anticoagulant medications such as warfarin should exercise caution, as the rutin content may have mild antiplatelet activity that could potentiate bleeding risk. Purple amaranth contains moderate levels of oxalates, which may contribute to kidney stone formation in susceptible individuals and should be limited by those with a history of calcium oxalate nephrolithiasis. Pregnant and breastfeeding women should restrict use to culinary food amounts rather than supplemental extracts, as safety data in these populations is absent.