Natural plant toxins in food: A comprehensive review of health implications, processing changes and regulatory challenges

• Provides a comprehensive overview of natural toxicants, with a focus on their presence in food. • Explores toxicological mechanisms supported by evidence from in vivo studies. • Discusses health risks associated with dietary exposure and their public health relevance. • Evaluates current regulatory guidelines and safety limits across regions. • Identifies research gaps and proposes future directions for risk assessment and management. Plants produce diverse secondary metabolites such as cyanogenic glycosides, glycoalkaloids, glucosinolates, pyrrolizidine alkaloids, and lectins, which act as defense systems against predators. While beneficial for plants, these compounds may adversely affect humans and other organisms, causing acute poisoning, chronic health disorders, or even fatality. They are found in common foods, including almonds, potatoes, cruciferous vegetables, legumes, cassava, and others. For instance, cassava releases 900–2000 mg Hydrogen Cyanide (HCN)/kg from cyanogenic glycosides, far exceeding the safe threshold of 10 mg/kg, while mustard seeds contain glucosinolates up to 60,000 ppm. Numerous in vitro and in vivo studies confirm that these metabolites exert both beneficial and harmful outcomes depending on the dose, frequency, and individual susceptibility. At optimal intake, they exhibit anti-cancer, antioxidant, anti-microbial, and anti-inflammatory properties. However, excess or prolonged intake can result in nausea, vomiting, gastrointestinal disturbances, neurological damage, teratogenic effects, or long-term effects. Traditional processing techniques, such as boiling, fermentation, and germination, along with modern approaches like high-pressure processing, gamma irradiation, and microwave heating, effectively lower the toxin content. Regulatory bodies, including the World Health Organisation (WHO), European Food Safety Authority (EFSA), and Food and Agriculture Organisation (FAO), have established permissible thresholds to safeguard public health.