Ikigai Daily
Menu
StillnessHealth fact

About 90% of the body's serotonin, a chemical messenger, is made in the gut, where it helps move food along. Serotonin cannot pass from the blood into the brain, so the brain makes its own supply separately.

Health science

Health

The story behind the card

Serotonin was named in 1948 by researchers at the Cleveland Clinic, who found a substance in blood serum that tightened blood vessels: sero- for serum, -tonin for tone. An Italian scientist, Vittorio Erspamer, had already found it in the gut in the 1930s and called it enteramine; in 1952 the two proved to be the same molecule. In the gut, lining cells called enterochromaffin cells release it when food arrives, making the intestine contract. Platelets, the blood cells involved in clotting, soak up much of the rest. The brain's serotonin, only about 1 to 2% of the total, is made by small clusters of nerve cells in the brainstem called the raphe nuclei. A protective filter, the blood–brain barrier, keeps gut serotonin out, so the gut's large share does not mean it directly controls mood.

Türkçe oku
Vücuttaki serotoninin yaklaşık %90'ı bağırsakta üretilir. Kimyasal bir haberci olan serotonin, orada besinlerin ilerlemesine yardım eder. Kandaki serotonin beyne geçemez; bu yüzden beyin kendi serotoninini ayrıca üretir.

Serotonin adını 1948'de, kan serumunda damarları daraltan bir madde bulan Cleveland Clinic araştırmacılarından aldı: “Sero-” serumu, “-tonin” damar gerginliğini, yani tonusu anlatır. İtalyan bilim insanı Vittorio Erspamer aynı maddeyi 1930'larda bağırsakta bulmuş ve ona enteramin demişti; 1952'de ikisinin aynı molekül olduğu anlaşıldı. Bağırsağın iç yüzeyindeki enterokromafin hücreler, besin geldiğinde serotonin salgılar ve bağırsağın kasılmasını sağlar. Geri kalanın büyük kısmını, kanın pıhtılaşmasında görev alan trombositler depolar. Beyindeki serotonin toplamın ancak %1-2'si kadardır ve beyin sapındaki rafe çekirdekleri denen küçük sinir hücresi kümelerinde üretilir. Kan-beyin bariyeri denen koruyucu süzgeç, bağırsaktaki serotoninin beyne geçmesini engeller. Bu yüzden serotoninin çoğunun bağırsakta üretilmesi, ruh hâlimizi doğrudan bağırsağın yönettiği anlamına gelmez.

Sources and further reading

Background reading: Serotonin
Get the mobile appAbout our cards

Related cards

These cards share a subject or reading mode with the card above.

DrivePhilosophy

He who has health has hope, and he who has hope has everything.

English quotation books have called this an “Arabian proverb” since at least the 1860s; Tryon Edwards's A Dictionary of Thoughts (1891) is one, but these books give no Arabic original, so the label is best taken loosely. The idea is widely shared: good health gives people the strength to plan and to recover from setbacks. Turkish says “Her şeyin başı sağlık”, health comes first, and when a glass breaks people say “Sağlık olsun”: never mind, as long as everyone is well.

Spanish, Arabic variants ProverbRead card
DriveHealth

Protein helps with satiety, the feeling of fullness that lasts after a meal. Meals that include beans and lentils, eggs, fish, dairy or other protein sources can help people feel full for longer, although appetite and digestion vary from person to person.

In studies that compare meals with the same number of calories, the higher-protein version usually keeps people satisfied for longer, although the effect is modest. One reason is that protein prompts the gut to release more of the hormone PYY, which tells the brain that food has arrived; a 2006 study led by Rachel Batterham at University College London found the strongest PYY response after high-protein meals. Another is that the body works harder to process protein: a 2004 review by the Maastricht University physiologist Klaas Westerterp reports that digesting and using it burns 20 to 30% of its calories, against 5 to 10% for carbohydrate and up to 3% for fat. UK guidance puts adults' needs at about 0.75 g of protein per kilogram of body weight a day, around 45 g for women and 56 g for men, and average intakes are well above that.

NHSRead card
StillnessHealth

The fibre we eat comes from plant foods: fruit, vegetables, wholegrains, beans and lentils, nuts and seeds. Meat, fish, eggs and dairy naturally contain none.

Fibre is the part of plant food that our digestive enzymes cannot break down. Much of it comes from the walls of plant cells, which give stems, peel and seeds their structure. Animals do not make these substances, so meat, fish, eggs and milk contain none. Mushrooms, which are fungi rather than plants, also supply a little fibre from their own cell walls. Nutritionists divide fibre into two kinds. Soluble fibre, found in oats, barley, apples and beans, dissolves in water in the gut, can form a gel and helps lower cholesterol. Insoluble fibre, in wholegrains, brown rice, nuts and the skins of fruit and vegetables, adds bulk and helps food pass through. Once fibre reaches the large intestine, gut bacteria ferment part of it into short-chain fatty acids, compounds that feed the cells lining the bowel.

NHS InformRead card
StillnessHealth

Whole fruit keeps its fibre and cell structure, so it takes longer to eat and fills you up more than juice. Juicing breaks the cells open and frees their sugars, which are harder on teeth. The NHS therefore counts juice as one of your five daily portions at most, and advises no more than 150ml a day.

In a 2009 study at Pennsylvania State University, Julie Flood-Obbagy and Barbara Rolls gave 58 adults an apple, apple sauce or apple juice 15 minutes before lunch, each with the same weight and calories. After the whole apple, people felt fuller and ate about 15% fewer calories across the starter and lunch together than on days with no starter. Juice did not have that effect, even with the apple's fibre added back. A larger Harvard analysis of about 187,000 American health professionals, published in the BMJ in 2013, found that people who ate more whole fruit, especially blueberries, grapes and apples, were less likely to develop type 2 diabetes, while those who drank more fruit juice were slightly more likely to. Long-term observational studies like this show a link rather than proof of cause, but the two kinds of evidence point the same way.

NHS InformRead card
StillnessHealth

Water makes up about 60% of an adult's body weight. The body needs it to control its temperature, keep blood flowing, digest food and keep organs working. When lost fluid is not replaced, thirst can come with tiredness, headache, dizziness and poorer concentration.

Every day we lose water in urine, in sweat and even in our breath, and more in hot weather or during exercise. About a fifth of what we take in comes from food, especially fruit and vegetables, and the rest from drinks. The NHS suggests 6 to 8 glasses of fluid a day, and water, lower-fat milk, tea and coffee all count. Thirst is the body's alarm: when the blood becomes slightly too concentrated, sensors in the hypothalamus, a small region at the base of the brain, trigger the urge to drink. This alarm weakens with age, which is one reason older people become dehydrated more easily. A simple check is the colour of urine: the NHS advises drinking enough to keep it a clear pale yellow, and darker urine is a sign to drink more.

Harvard T.H. Chan School of Public HealthRead card
Next card in the archiveA Finnish study that followed 2,315 middle-aged men for about 20 years found that those who took a sauna four to seven times a week were less likely to die of heart disease, or of any cause, than those who went once a week. It shows a link, not proof that the sauna did it.Read next →