Hemp Seed

Industrial hemp is a tall, fast-growing annual with slender stems and palmate leaves, grown for fibre, seed or both. Its fruit is a small achene, a hard, rounded or slightly oval shell about three to five millimetres long, mottled grey-brown and often with a faint marbled pattern. The shell encloses a soft, creamy-green to off-white kernel with a mild, nutty, slightly grassy flavour that resembles sunflower seed crossed with pine nut. Seeds are sold whole in the shell, hulled as hemp hearts, as roasted snacks, as protein powder made from the pressed cake, as cold-pressed oil with a green tint, and as flour and milk. Food-grade hemp is bred to contain only trace amounts of the psychoactive compound THC.

Cannabis is thought to have originated in Central Asia, and hemp is among the oldest cultivated plants, grown for fibre and seed for thousands of years in East Asia and later across Eurasia. Archaeological finds in China include hemp fibre and seeds from Neolithic settlements. The word hemp comes from Old English haenep, related to Germanic cognates, and the genus name Cannabis traces back through Greek kannabis, probably borrowed from an older language of the Eurasian steppe. Today the main seed producers are Canada, China and several European countries, where hemp has been regulated as a distinct crop separate from drug-type cannabis.

Hemp seed has been food, medicine and bird feed for millennia. Chinese texts describe the seeds as a grain, and hemp seed was counted among the traditional five grains in some early Chinese lists. In medieval Europe, hempseed gruel and porridge fed peasants, especially in times of scarcity, and the oil was burned in lamps. The fibre side of the crop overshadowed the seed for centuries: hemp rope and canvas rigged sailing ships, and the word canvas itself derives from cannabis. In the twentieth century, drug-control laws that did not clearly distinguish hemp from marijuana halted cultivation in many countries, including the United States, and food use faded from public view. Modern hemp revival began in the 1990s when Canada and several European countries reintroduced licensed low-THC cultivars. Hemp hearts then became a staple of health-food shops, and in 2018 the United States removed hemp from its list of controlled substances, opening a wider market. Researchers continue to study the seed protein edestin and the oil's fatty acid profile.

Hulled hemp seeds are sprinkled over yoghurt, oatmeal, salads and smoothies, blended into dressings and pesto, or ground into energy balls and baked goods. Hemp milk and hemp protein powder are common in vegan cooking. The cold-pressed oil is used unheated in dressings and drizzles because it is delicate. In traditional Chinese medicine, huo ma ren is used as a gentle laxative in formulas. Whole seeds are widely sold as bird food and fishing bait, while the oil appears in some cosmetics and varnishes, and the pressed cake is fed to livestock.

Hulled hemp seeds supply complete protein of good digestibility and are a source of magnesium, phosphorus, zinc and iron. The oil is unusually high in linoleic and alpha-linolenic acids in a ratio considered favourable, and also contains gamma-linolenic acid. Reviews describe potential cardiovascular and anti-inflammatory benefits, but most evidence comes from animal or small human studies, so claims should be seen as preliminary. Whole seeds with the shell supply considerably more fibre than hearts. Hemp foods are best regarded as nutritious additions to a varied diet rather than treatments.