Apricot kernels are the small seeds found inside the hard, woody pit of the apricot fruit. These kernels resemble small almonds and possess a distinctly bitter flavor in certain varieties. They are often marketed under the misleading names “Vitamin B17” or Laetrile, creating a public perception that they are a natural health supplement. Despite these claims, the kernels contain a naturally occurring chemical compound that poses a health risk. Understanding safe consumption limits is necessary due to the controversy surrounding their potential benefits versus their established toxicity.
The Safe Consumption Limits
Regulatory authorities have established low consumption limits for apricot kernels due to the potential for acute toxicity. The European Food Safety Authority (EFSA) determined a safe level for a single exposure, known as the Acute Reference Dose (ARfD), which is the maximum amount of a substance that can be ingested over a short period without an adverse health effect. Based on this threshold, EFSA experts estimate that an average adult should consume no more than three small raw apricot kernels in a single serving.
The precise number of safe kernels is complicated because the concentration of the toxic compound varies widely depending on the apricot variety and geographical origin. For larger kernels, the limit is stricter; consuming less than half of one large kernel can exceed the safe limit for an adult. Bitter varieties contain substantially higher levels of the toxic substance than “sweet” kernels. Due to this high variability, even a small dose can be unsafe.
Children are at a much higher risk of toxicity and should avoid consuming apricot kernels entirely. EFSA advises that toddlers should not consume more than approximately one-half of one small kernel, as even a single small kernel can risk exceeding their safe exposure level. The practice of consuming kernels for claimed health benefits, with some promotions recommending up to 10 to 60 kernels per day, far exceeds established safety limits and carries a risk of poisoning.
The Source of Toxicity in Apricot Kernels
The danger in apricot kernels stems from a naturally occurring compound called Amygdalin. Amygdalin is classified as a cyanogenic glycoside, a plant metabolite that contains a cyanide group. Although often marketed as a vitamin, it has no recognized nutritional function.
When the kernel is chewed or digested, Amygdalin is broken down in the gastrointestinal tract by enzymes. These enzymes, primarily beta-glucosidases, are present in the kernel and are also produced by gut bacteria. This enzymatic breakdown releases two molecules of glucose and a molecule of mandelonitrile. Mandelonitrile is unstable and rapidly decomposes, yielding benzaldehyde and the toxic compound, hydrogen cyanide (HCN).
Hydrogen cyanide is a cellular poison because it interferes with the body’s ability to use oxygen. Specifically, cyanide binds to a protein complex called cytochrome c oxidase within the mitochondria of cells. This binding effectively halts cellular respiration, the process by which cells generate energy using oxygen. When this pathway is blocked, tissues, especially the brain and heart, are rapidly starved of usable oxygen, leading to cellular death and systemic failure. Oral consumption of Amygdalin utilizes the gut’s enzymes for conversion, resulting in a higher risk of toxicity.
Recognizing Symptoms of Cyanide Poisoning
The effects of consuming toxic levels of Amygdalin manifest as symptoms of cyanide poisoning, ranging from mild to life-threatening. The onset of symptoms can be rapid, as cyanide quickly impairs the body’s oxygen utilization. Initial symptoms of acute exposure include anxiety, restlessness, and a headache. These are often followed by digestive upset, such as nausea and vomiting, along with weakness, lethargy, and lightheadedness.
As the dose of cyanide increases, symptoms become more severe, reflecting the lack of oxygen reaching vital organs. Individuals may experience confusion, difficulty breathing, and a rapid or irregular heart rate. A distinctive sign of severe poisoning is cyanosis, a bluish discoloration of the skin and mucous membranes, which indicates low blood oxygen saturation. At the highest toxic levels, poisoning can quickly escalate to seizures, stupor, loss of consciousness, and metabolic acidosis, potentially leading to coma, cardiovascular collapse, and death. If any of these symptoms appear after consuming apricot kernels, emergency medical attention should be sought immediately.