Stone Fruit

TL;DR. Peaches, nectarines, plums, cherries, and apricots are all Prunus, all close relatives of the almond, and all carry cyanide-releasing compounds in the kernel inside the stone. They are climacteric, so they can be picked hard and shipped, and this is why supermarket stone fruit is so frequently a disappointment: picked underripe it never develops sugar or aroma, only softness. Cherries are the exception, non-climacteric and therefore expensive. Prunes for constipation is one of the best-evidenced food remedies there is, better than psyllium in head-to-head trials.

1. What it is

Genus Prunus, family Rosaceae. The fruit is a drupe: a fleshy layer around a hard endocarp (the stone) containing a single seed (the kernel).

That last row is the striking one: an almond is a stone fruit whose flesh is thin and inedible, so we crack the stone and eat the seed. Everything else in the list, we do the opposite.

2. Where it comes from

Peach: China, domesticated around 6000 BCE, with archaeological peach stones from the Yangtze valley. The species name persica reflects the Roman assumption that it came from Persia, which was merely the route.

Apricot: China and Central Asia, spread west through Armenia (hence armeniaca).

Sweet cherry: the Caspian and Black Sea region, spread by Greeks and Romans. Sour cherry is a natural hybrid of sweet cherry and the ground cherry P. fruticosa.

European plum is an ancient hexaploid hybrid of the cherry plum and the sloe, probably arising in the Caucasus.

Production (approximate): peaches and nectarines around 25 million tonnes, with China producing well over half; plums around 12 million tonnes, again China-dominated; cherries around 2.5 million tonnes led by Turkey, Chile, the US, and Uzbekistan; apricots around 4 million tonnes led by Turkey, Uzbekistan, and Iran. California produces the large majority of the world's dried prunes and a substantial share of dried apricots.

Chile's cherry export industry deserves a mention as one of the strangest supply chains in food: the great majority of its crop is flown and shipped to China for Lunar New Year, where red fruit is auspicious, in a compressed few-week window at extraordinary prices.

3. How it is grown

Climate. Temperate, with a real chilling requirement:

Apricot's low chill requirement combined with very early bloom makes it the most frost-vulnerable major fruit in temperate climates: it wakes up at the first warm spell and loses its flowers to the next frost. This is why apricot crops fail so often in Britain and northern Europe and why the fruit is expensive.

Peach needs heat to develop sugar, so the best peaches come from continental climates with hot summers (Georgia and California in the US, the Rhône valley, Emilia-Romagna, Murcia).

Cherries hate rain at harvest. A ripe cherry absorbs water through its skin and splits, and a single rain event days before picking can destroy a crop. Growers respond with permanent rain covers, with anti-transpirant sprays, and, famously in Michigan and Washington, with helicopters hovering over orchards to blow the water off the fruit.

Soil. Well-drained, and stone fruit is even less tolerant of wet feet than apples. Phytophthora and bacterial canker follow waterlogging. pH 6.0 to 7.0.

Trees. Grafted, on rootstocks that control size and tolerate soil conditions. Peach on Nemaguard or Lovell; cherry on the dwarfing Gisela series, which revolutionised cherry growing by bringing trees down from 10 metres to a pickable 3 to 4 metres; plum on Myrobalan or St Julien.

Pollination. Varies importantly by fruit. Peaches, nectarines, and apricots are largely self-fertile and need only bees, not a second variety. Most sweet cherries are self-incompatible and need a compatible partner flowering simultaneously, though self-fertile cultivars (Stella, Lapins, Sunburst) have been bred and simplified orchard design considerably. Plums vary by cultivar.

Thinning is critical and severe. Peaches are thinned to roughly one fruit every 15 to 20 cm along a branch, which means removing most of the crop. Unthinned peaches are small, pale, and lacking sugar. This is one of the biggest hand labour costs in the crop.

Harvest. Hand-picked. Stone fruit other than cherries is climacteric, so it is picked firm for shipping. Cherries are non-climacteric and must be picked ripe, which is why they arrive in a punnet, cost what they cost, and last a week at best.

Post-harvest. The characteristic disaster of peaches and nectarines is chilling injury or "internal breakdown": fruit held between roughly 2 and 8 °C for too long develops mealy, dry, woolly flesh and fails to ripen properly. The correct handling is either to ripen at room temperature first, or to store below 0.5 °C, and the domestic fridge sits squarely in the damaging zone. This is the mechanistic reason so many supermarket peaches are woolly, and it is entirely a supply chain failure rather than a variety problem.

4. What is inside it

Per 100 g raw:

Notable points:

• Apricots are the carotenoid standout, with beta-carotene giving both the colour and substantial provitamin A. Dried apricots concentrate this further.
• Prunes are exceptional: 7 g of fibre per 100 g, over 700 mg of potassium, high in vitamin K, and around 15 g of sorbitol, which is the key to their action.
• Tart cherries contain notably high anthocyanins and measurable melatonin, which is the basis of the sleep research below.
• Sorbitol is a sugar alcohol present in most stone fruit and concentrated in prunes. It is poorly absorbed, draws water into the bowel osmotically, and is fermented. That is both the laxative mechanism and the reason stone fruit is high-FODMAP.

5. What it does in your body

Prunes and constipation is the best-supported food remedy in this book. The mechanism is three-part: about 7 g of fibre per 100 g, roughly 15 g of sorbitol drawing water into the lumen osmotically, and phenolic compounds with a mild stimulant effect on the colon. A randomised crossover trial by Attaluri and colleagues compared 50 g of prunes twice daily against psyllium and found prunes produced more complete spontaneous bowel movements and better stool consistency. Subsequent reviews and a 2022 meta-analysis support prunes as a first-line dietary treatment. Roughly 50 to 100 g a day (5 to 10 prunes) is the effective dose, built up gradually.

Prunes and bone is a smaller but genuine story: several trials, including work led by Bahram Arjmandi, have found that 50 to 100 g of dried plums daily preserved bone mineral density in postmenopausal women better than control, plausibly via polyphenols suppressing bone resorption. The 2022 Prune Study confirmed benefit at 50 g/day. It is a modest effect from a food, which is a reasonable thing to know.

Tart cherry and sleep has a plausible mechanism (measurable melatonin plus tryptophan availability) and a handful of small positive trials showing modest increases in sleep time and efficiency in older adults and insomniacs. The effect sizes are small and the trials are small.

Tart cherry and exercise recovery / gout has better support: several trials find reduced muscle soreness and faster strength recovery after intense exercise, and observational and small trial data suggest reduced gout flare frequency, plausibly because anthocyanins reduce uric acid and inflammation. The gout finding, from Zhang and colleagues, showed roughly a 35 percent lower flare risk with cherry intake, and it is observational.

Carotenoids from apricots convert to vitamin A, with all the caveats about conversion efficiency in Chapter 15.

6. What the evidence actually shows

Established: prunes relieve constipation, and the mechanism is well characterised. Apricots are a good provitamin A source.

Strong: stone fruit contributes to the general whole-fruit association with lower cardiovascular and diabetes risk. Prunes for bone density in postmenopausal women has multiple supporting trials.

Mixed: tart cherry for sleep and for exercise recovery. Positive, small, and worth trying if the problem matters to you.

Thin: anything about peaches specifically. Apricot kernels for cancer is not thin, it is actively harmful, and it is covered below.

7. Who should eat more, who should be careful

Good for: most people. Prunes specifically for anyone with constipation, particularly older adults, people on opioids, and during pregnancy, where stimulant laxatives are less desirable.

Be careful if:

• IBS or FODMAP sensitivity. Stone fruit is the highest-FODMAP fruit category, thanks to sorbitol. Peaches, plums, cherries, apricots, and especially prunes are all common triggers. This is the single most likely fruit family to cause bloating and cramps.
• You eat a lot of dried fruit. Sorbitol at high doses causes osmotic diarrhoea in anyone.
• Sulphite sensitivity. Bright orange dried apricots are sulphited; brown ones are not. Sulphites can trigger asthma.
• Oral allergy syndrome. Very common with peach and cherry in birch-pollen-allergic people (Pru p 1). Separately, peach Pru p 3, a lipid transfer protein concentrated in the skin, is heat-stable and causes genuine systemic allergic reactions, particularly in Mediterranean populations. Peach is one of the more common causes of food anaphylaxis in Spain and Italy. Peeling reduces the risk substantially because the protein concentrates in the skin.
• Diabetes. Fresh stone fruit is moderate; dried stone fruit is concentrated sugar.

Ages. Fine from 6 months as soft or cooked pieces. Cherry stones and whole cherries are a choking hazard; stone and halve for young children.

The kernels. The seed inside the stone contains amygdalin, which releases cyanide when crushed and digested. Swallowing a stone whole is harmless; the shell passes through. Apricot kernels sold as a health food or as "vitamin B17" / laetrile are genuinely dangerous. EFSA assessed that as few as three small kernels can exceed the acute reference dose for an adult and one for a toddler; poisonings and deaths are documented. Laetrile has been tested as a cancer treatment in controlled trials and does not work (Chapter 18).

Bitter almonds carry the same compound and are not sold as food in most countries; sweet almonds have been bred to contain almost none.

8. When and how to eat it

• Buy in season, locally, if you possibly can. No fruit category degrades more between a tree-ripened example and a shipped one. A tree-ripened peach in August and a supermarket peach in March are barely the same food.
• Ripen at room temperature, in a paper bag if you want speed. Stone fruit is climacteric and will soften and sweeten after picking, though the sugar it can develop is capped by what it accumulated on the tree.
• Only refrigerate once fully ripe, and then only for two or three days. The mealy-woolly peach is caused by refrigerating an unripe one.
• Eat the skin. It carries most of the polyphenols and fibre. The exception is anyone with peach LTP allergy, for whom the skin is exactly the problem.
• Cook them. Roasting or grilling stone fruit concentrates sugar and works well; poaching is the classic treatment for underripe fruit that will never improve on its own.
• Prunes: start at 3 to 4 a day and build to 8 to 10, with water, to avoid a dramatic first experience.

9. Choosing, storing, and ripening

Choosing.

• Smell the stem end. This is the most reliable test for peaches, nectarines, apricots, and plums. Ripe fruit smells of itself. No smell means it was picked too early and no amount of waiting will fix it.
• Slight give at the shoulders, near the stem, not at the tip. Pressing the tip bruises it.
• Background colour, not blush. The red blush on a peach is a variety and sun-exposure trait, not ripeness. The background colour between the red should be creamy or golden, not green. A green ground colour means immature.
• Cherries: green, flexible stems and firm, glossy fruit. Cherries are non-climacteric, so what you buy is what you get.
• Plums: a dusty bloom, and slight give.

Storing. Counter until ripe, then fridge for a few days. Cherries go straight in the fridge and last about a week. Prunes and dried apricots keep for months in a sealed container, and refrigerating them keeps them softer.

10. The varieties worth knowing

Peaches split into clingstone (flesh adheres to the stone; used for canning, juicier) and freestone (flesh separates cleanly; the eating peach). Yellow-fleshed peaches are higher in carotenoids and more acidic; white-fleshed are lower acid and taste sweeter at the same sugar level. Donut/Saturn peaches are flat, white-fleshed, and low acid.

Nectarines are genetically peaches minus the fuzz; they tend to be slightly firmer and more aromatic.

Plums: European types (Victoria, damson, greengage, mirabelle, Italian prune plum) are firmer, sweeter, oval, and are the ones that dry into prunes. Japanese types (Santa Rosa, Methley) are rounder, juicier, more acidic, and eaten fresh. Damsons and sloes are too astringent to eat raw and go into jams and gin respectively.

Cherries: sweet cherries (Bing, Lapins, Rainier, Sweetheart, Regina) for eating; sour/tart cherries (Montmorency, Morello) for cooking, juice, and the research above. Almost all tart cherry research uses Montmorency.

Apricots: Turkish (Hacihaliloglu) types dominate drying; Blenheim/Royal is the classic Californian flavour variety; Hunza apricots from Pakistan are dried whole with the stone.

11. Myths and confusions

Don't be confused: a prune is a plum, and "dried plum" is the same product renamed. The California prune industry rebranded to "dried plums" in the early 2000s specifically because "prune" carried an association with constipation and old age. It is the same fruit, and the constipation association is the accurate part.

• "Nectarines are a cross between a peach and a plum." No. They are peaches with a recessive mutation in a single gene affecting skin fuzz.
• "Apricot kernels cure cancer." They do not, and they can cause cyanide poisoning. Laetrile failed in controlled trials.
• "Cherry juice is a proven sleep aid." Small, modest, promising, not proven.
• "Peaches should be kept in the fridge." Not until fully ripe, and this single error causes most woolly peaches.
• "A red peach is a ripe peach." The blush is variety and sun. Look at the background colour and smell it.

12. The bottom line

• Stone fruit is one genus: peaches, plums, cherries, apricots, and almonds are close cousins, and all carry amygdalin in the kernel.
• Everything except cherries is climacteric and shipped hard, which is why quality varies so much and why smelling the stem end is the only reliable purchase test.
• Do not refrigerate unripe peaches and nectarines; the 2 to 8 °C window is what makes them woolly.
• Prunes for constipation is genuinely well evidenced and outperformed psyllium in a head-to-head trial. There is also decent evidence for prunes and bone density after menopause.
• This is the highest-FODMAP fruit family, and apricot kernels sold as health food are a real poisoning hazard.

Sources and notes

Composition figures are from USDA FoodData Central; production figures are approximate FAOSTAT values for the early 2020s. Peach domestication follows Zheng et al.'s Yangtze archaeobotanical work. Cultivation, chilling requirements, thinning, and post-harvest chilling injury (internal breakdown) follow Washington State, UC Davis, and Michigan State extension publications and USDA Handbook 66. Cherry rain-cracking and helicopter drying are documented in Pacific Northwest cherry extension material. Prunes for constipation is Attaluri et al., Alimentary Pharmacology and Therapeutics, 2011, comparing prunes with psyllium, plus subsequent meta-analyses. Prunes and bone density follow Hooshmand and Arjmandi's trials and the 2022 Prune Study. Tart cherry and sleep follows Howatson et al., European Journal of Nutrition, 2012; exercise recovery follows Bell et al.'s trials; gout flares follow Zhang et al., Arthritis and Rheumatism, 2012. Pru p 1 and Pru p 3 allergen behaviour follows Fernandez-Rivas' Mediterranean LTP allergy work. Apricot kernel toxicity follows the EFSA 2016 opinion; laetrile trial failure is Moertel et al., NEJM, 1982.

Open questions. Tart cherry sleep and recovery trials are consistently small and often industry-funded, and effect sizes vary widely. The prune bone-density finding is promising and has not been replicated at scale.

👉 Next: melons, which are botanically vegetables and a repeat cause of serious food poisoning.