50 Fascinating Facts About Human Diets and Eating Habits

Human beings can thrive on surprising foods, suffer from seemingly harmless diets, and reshape entire eating traditions through science, scarcity, migration, and marketing. From ancient meals preserved in pottery to modern research on nutrition and gut bacteria, our food choices reveal how adaptable and vulnerable the human body can be. These facts explore the strange, clever, and sometimes dangerous ways people have eaten throughout history.

1 Potatoes And Buttermilk Sustained Ireland

Although potatoes alone do not provide complete nutrition, people can survive for years on a diet of potatoes and buttermilk. Potatoes provide calories, vitamin C, potassium, magnesium, iodine, and certain B vitamins, while buttermilk supplies vitamin B12, calcium, and vitamin A. This combination sustained much of Ireland’s population for generations before the 1845 potato blight, with some adult men consuming 5 to 6 kilograms of potatoes per day.

2. Introducing peanut products into babies’ diets between 4 and 6 months of age could reduce peanut allergies across the population by up to 77%. Researchers led by the University of Southampton, King’s College London, and the National Institute for Health and Care Research found that most peanut allergies develop before age 1. Waiting until 12 months could reduce cases by only 33%. Researchers recommend introducing suitable peanut products at 4 months for babies with eczema, using smooth peanut butter or baby-safe peanut snacks rather than whole or broken peanuts.

3. A British teenager who ate French fries, Pringles, white bread, and occasional slices of ham or sausage developed severe vitamin deficiencies, malnutrition damage, and blind spots in the center of his vision. At age 14, he visited a doctor for fatigue and received vitamin B12 injections and dietary advice, but he did not follow the treatment or change his diet. By age 17, tests revealed deficiencies in vitamin B12, copper, selenium, and vitamin D, and doctors diagnosed nutritional optic neuropathy caused by damage to the optic nerve. His central sight loss permanently impaired his ability to read, watch television, and recognize faces.

4. Some Australians follow a diet called kangatarianism, which excludes every type of meat except kangaroo for environmental and ethical reasons. Supporters otherwise eat a vegetarian diet and argue that wild kangaroos require no additional farmland or water while producing little methane compared with cattle and other livestock.

5. A 2022 study proposed that martial artist and actor Bruce Lee may have died from hyponatraemia, a dangerously low sodium concentration that can develop when excess water dilutes the blood. At the time of his death in Hong Kong in 1973, the 32-year-old had reportedly stopped eating solid food and was living mostly on carrot and apple juice. Researchers argued that chronic fluid intake and other factors may have prevented Lee’s kidneys from removing enough water. They suggested the resulting hyponatremia may have caused the cerebral edema found during his autopsy.

6 High-Fiber Diets Reduce Calorie Absorption

People absorb fewer calories overall from a high-fiber diet than from a Western diet rich in processed foods, according to a 2025 Arizona State University-led study. Researchers gave participants both diets with identical proportions of carbohydrates, proteins, and fats, then measured their metabolism inside sealed whole-room calorimeters. Nearly everyone absorbed fewer calories from the high-fiber diet, although participants with methane-producing gut microbes extracted more energy from it than those who produced less methane.

7. A person can die from eating only rabbits without another source of fat or carbohydrates because rabbit meat is extremely lean. This condition, called protein poisoning or rabbit starvation, occurs when someone consumes excessive lean protein without enough alternative energy sources. Arctic explorer Vilhjalmur Stefansson described the condition among people forced to survive on lean animals such as rabbits, although actual deaths were rare.

8. Eating the Australian aquatic fern nardoo without preparing it correctly can make a person starve even while consuming enough nutritious food. Nardoo contains large quantities of thiaminase, an enzyme that destroys thiamine, or vitamin B1, which the body needs to release energy from food. During their 1861 expedition, British explorers Robert O’Hara Burke and William John Wills grew weaker despite eating up to 4 or 5 pounds of nardoo between them daily. Aboriginal Australians made the plant safe by roasting its spore cases before grinding them, as heat destroys the thiaminase.

9. A 2022 systematic review found that low-carbohydrate, high-protein diets greatly decreased resting total testosterone in healthy men. Researchers defined low carbohydrate as 35% or less of total energy and high protein as 35% or more.

10. Roman gladiators were often overweight and ate mostly vegetarian diets rather than developing the lean, muscle-bound bodies shown in movies. Austrian scientists analyzed bones from about 70 gladiators buried at Ephesus, near Selcuk in modern Turkey, and found that they mainly ate barley, beans, and dried fruit. Researchers suggested that this carbohydrate-heavy diet created a protective layer of fat that shielded vital organs, nerves, and blood vessels from cutting wounds.

11 British Rationing Improved Wartime Health

Food rationing during World War II increased life expectancy and reduced infant mortality in the United Kingdom, excluding deaths caused by the fighting. Rather than forcing everyone to eat a prescribed menu, the system ensured access to a varied diet containing enough vitamins while reducing fat and sugar consumption and increasing milk and fiber intake. The government also gave young children free blackcurrant syrup and bottled orange juice while providing subsidized milk to children under 5 and expectant mothers.

12. Chemical analysis of ancient West African pottery revealed organic residues from meals prepared by the Nok people as early as 3,500 years ago. Researchers examined 458 prehistoric vessels from 10 sites in central Nigeria and found diverse plant lipid profiles in more than one-third of them. The evidence indicates that Nok cooks processed leafy greens, cereals, pulses, and possibly yams, with the greens likely including African eggplant, okra, cowpea, jute mallow, and bombax.

13. Iceberg lettuce consists of nearly 96% water, making it less nutrient-dense than most darker leafy greens. One shredded cup contains less than 1 gram of fiber and only trace amounts of calcium, iron, vitamin C, and vitamin K.

14. Ordinary food cravings during pregnancy generally do not correlate with maternal nutritional imbalances, and researchers still do not know their exact cause. Studies indicate that 66% to 90% of expectant mothers experience at least one craving, but popular choices vary across cultures, arguing against a universal nutritional cause. One exception is pica, a compulsive urge to consume non-food substances such as chalk, rocks, or ice chips. Pica may indicate a mineral deficiency or severe anemia.

15. Golden Rice is a genetically modified crop designed to improve nutrition and fight malnutrition in low-income regions where rice forms a major part of the diet. Ordinary rice grains contain neither vitamin A nor its precursors, so scientists inserted genes that allow the grain to produce beta-carotene, which the body converts into vitamin A. The beta-carotene gives the rice its golden color.

16 Quinoa Could Feed Space Crews

NASA researchers identified quinoa as a potential crop for its Controlled Ecological Life Support System in 1993 because of its nutritional value for long-duration crewed space missions. Quinoa contains 12% to 18% protein and supplies all essential amino acids in favorable proportions, making it unusually complete among plant foods.

17. Oregon State University researchers patented a fast-growing strain of red seaweed called dulse that reportedly tastes like bacon when fried and offers twice the nutritional value of kale. Marine biologist Chris Langdon and his team originally cultivated it as food for edible sea snails called abalone. The dulse contains vitamins, minerals, antioxidants, and up to 16% protein by dry weight. After business professor Chuck Toombs recognized its potential for human consumption, the university’s Food Innovation Center began developing products such as rice crackers and salad dressing from it.

18. To combat widespread iron deficiency, Cambodian families add fish-shaped iron ingots called Lucky Iron Fish to their cooking pots. Canadian physician Christopher Charles initially tested plain iron lumps, but women used them as doorstops, so he molded them into the “try kantrop,” a fish considered lucky in Cambodian culture. Boiling the fish in food or water releases iron, while added citrus juice helps the body absorb it. Studies found that 90% of test subjects used the fish regularly and were more than 10 times as likely to achieve normal blood iron levels as a control group.

19. Beginning in January 2020, the U.S. Food and Drug Administration stopped requiring vitamins A and C on updated Nutrition Facts labels because deficiencies had become uncommon compared with when the labels were first created. Manufacturers may still list both vitamins voluntarily. The revised labels instead require vitamin D and potassium because many Americans do not consume enough of these nutrients.

20. On October 1, 2008, a 20-year-old Belgian student reheated spaghetti that had been prepared five days earlier and left at room temperature. Within 30 minutes, he developed a headache, abdominal pain, and nausea before vomiting for hours and suffering diarrhea. His parents found him dead the following morning, approximately 10 hours after he ate the meal. Tests found significant amounts of Bacillus cereus in the pasta, linking his death to the food poisoning commonly called “fried rice syndrome.”

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21 Pistachios Fed Humans For Millennia

Humans have eaten pistachios for approximately 8,750 years. Archaeological evidence shows that pistachio seeds had become a common food by 6750 BCE, while evidence of their later production comes from Bronze Age Djarkutan in modern Uzbekistan. Native to Iran and Central Asia, pistachio trees eventually reached Europe through the Romans during the first century AD.

22. Your body absorbs roughly 51% of an egg’s protein when you eat it raw, compared with about 91% when you cook it. Cooking changes the protein’s structure, allowing digestive enzymes to break it down more efficiently. Rocky Balboa, therefore, would have absorbed more protein by frying his famous training eggs instead of drinking them raw.

23. When chocolate develops a white or gray powdery coating, it has experienced either sugar bloom or fat bloom. Moisture causes sugar bloom by dissolving surface sugar, while temperature changes cause fat bloom by bringing cocoa butter to the surface. Both indicate improper storage rather than spoilage, so the chocolate remains safe to eat.

24. Kudzu, also known as Japanese arrowroot, is edible, and people have used its root in traditional Chinese medicine for more than 2,000 years. People can cook the root like a potato or grind it into powder, while the leaves, vine tips, and purple blossoms are also edible. However, avoid wild kudzu in the southern United States because it may have been treated with pesticides, and only consume plants that you have grown yourself.

25. Eating certain species of tropical and temperate fish can cause hallucinogenic fish inebriation, a rare poisoning sometimes likened to a three-day LSD trip. The salema porgy, or Sarpa salpa, can trigger a condition called ichthyoallyeinotoxism, producing vivid auditory and visual hallucinations, nightmares, nausea, and weakness. People supposedly consumed the fish recreationally in the Roman Empire and used it ceremonially in Polynesia, although modern cases remain rare.

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