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Hesperidin is one of the best-studied flavonoids in citrus fruit. Current research focuses on its relationship with markers of inflammation and oxidative balance.

What hesperidin is

Hesperidin is a natural plant compound belonging to the flavonoids, and more precisely to the flavanones. It is neither a vitamin nor a mineral, and no recommended daily intake has been established for it. In the plant it occurs as a glycoside: a hesperetin molecule is linked to a disaccharide made of glucose and rhamnose. The presence of the sugar moiety affects the compound's solubility and the way it is processed in the digestive tract.

Hesperidin dissolves poorly in water and is not absorbed in full in the small intestine. A significant part reaches the large intestine, where gut-bacteria enzymes detach the sugar moiety and release hesperetin. The compound can then be absorbed and converted mainly into glucuronide and sulfate derivatives. Differences in microbiota composition, the form of the preparation, particle size and meal composition can cause considerable inter-individual differences in availability.

Sources of hesperidin

Citrus fruits provide the most hesperidin, especially sweet and bitter oranges, mandarins, clementines and lemons. Its content depends on the species and variety, ripeness, growing and storage conditions, and processing. The compound is not evenly distributed — more is found in the peel, the white layer beneath it, the membranes separating segments and pressing residues than in the flesh itself.

Orange juice also contains hesperidin, but the amount can vary with the proportion of fine fruit particles, filtration and production technology. Supplements use, among others, purified, micronized or modified hesperidin to increase its solubility.

Inflammation and oxidative stress

Inflammation is a natural response to infection or tissue damage. In the short term it supports defence and repair, but when it persists too long it can proceed without clear symptoms. It is assessed using, among others, C-reactive protein (CRP), high-sensitivity CRP (hs-CRP), tumour necrosis factor alpha (TNF-α) and interleukin 6 (IL-6).

Oxidative stress arises when the body cannot keep up with neutralising reactive oxygen and nitrogen species. Their excess can lead to changes in lipids, proteins and DNA. Studies assess, among others, malondialdehyde (MDA), 8-hydroxy-2′-deoxyguanosine (8-OHdG) and total antioxidant capacity (TAC). The two processes are linked and can amplify each other, yet a change in a single marker does not automatically mean an improvement in health.

Results of the latest meta-analysis

In 2026 a pooled analysis of 10 studies involving 532 adults was published. Participants included both healthy people and those with type 2 diabetes, metabolic syndrome, fatty liver disease, after a heart attack or with periodontitis. The studies differed in the dose and form of hesperidin and the duration of use.

After synthesising the results, hesperidin use was associated with lower CRP, hs-CRP and TNF-α values. No clear difference was found in IL-6 across the whole group. Lower IL-6 values were found only in studies involving people with type 2 diabetes or after a heart attack. There were too few data on oxidative stress to draw firm conclusions — only one study assessed MDA and TAC.

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Saffron has been used for thousands of years as a spice and plant material. In 2026 an analysis of 34 studies evaluating its effect on symptoms of depression, anxiety and mood in adults was published.

What saffron is

Saffron is a spice obtained from the cultivated crocus, Crocus sativus L., of the iris family. The plant is small and perennial and grows from an underground corm. It usually flowers in autumn, producing pale-purple or lilac flowers. Inside the flower are three yellow stamens and long, intensely red stigmas.

It is the stigmas — not the whole petals or the stamens — that are hand-picked, dried and sold as true saffron. Crocus sativus does not propagate from seed but by dividing corms. Each plant produces few stigmas, and separating and drying them requires much labour, which contributes to the high price of the spice. Iran remains the most important producer.

Bioactive compounds of saffron

The most characteristic compounds of saffron are the crocins, picrocrocin and safranal. Crocins are water-soluble and are mainly responsible for the intense yellow-orange colour; during digestion they can be converted to crocetin. Picrocrocin is responsible for the bitterish taste, while safranal is a volatile aroma component whose amount increases during drying, among other processes.

The petals have a different chemical profile: they contain flavonoids and anthocyanins, but usually far fewer of the characteristic compounds found in the stigmas. For this reason petal powder, whole stigmas and a standardised extract are not equivalent raw materials.

Saffron and mood regulation

The 2026 review collected results from 34 studies published up to July 2025. The analysis covered 1,769 adults: 895 received saffron and 874 were included in control groups. Follow-up ranged from 4 to 12 weeks, and most studies were carried out in Iran. They included healthy people and patients with, among others, depression, Parkinson's disease, multiple sclerosis, type 2 diabetes or heart disease.

People taking saffron reported milder symptoms of depression and anxiety in self-completed questionnaires than those in placebo groups. On the Beck Depression Inventory the difference averaged 4.39 points, and on the Beck Anxiety Inventory 5.06 points in favour of saffron. However, no clear differences were found in clinician-rated assessments or in overall mood.

There were differences between individual results — in some studies the effect was clear, in others small or absent. Larger changes occurred more often after at least eight weeks. The data did not, however, allow the best dose or type of preparation to be identified.

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Probiotics are increasingly studied in the nutrition of physically active people and athletes. What do the latest data on their effect on performance show?

Probiotics from the ground up

Probiotics are live microorganisms that, given in an adequate amount, may confer a specific benefit on the host. Most often these are selected bacteria, though some yeasts can also be probiotics. The word "selected" is key — not every bacterium of the genus Lactobacillus or Bifidobacterium is automatically a probiotic, because properties are assessed at the level of a specific strain. This can be compared to varieties of the same plant species: they belong to one group but can differ markedly in their properties.

A product's label may show not only the genus and species name but also the strain designation. The number of live microorganisms, usually given as CFU (colony-forming units), also matters. A high CFU count alone does not determine a product's properties, however — what counts includes the strain used, its amount, storage conditions and maintaining an adequate number of live microorganisms over the declared period.

Probiotics versus fermented foods

A probiotic should not be equated with every fermented product. Yoghurt, kefir, sauerkraut or kimchi may contain live microorganisms, but calling a specific microorganism probiotic requires its identification and appropriate data on that strain.

Probiotics also differ from prebiotics. Prebiotics are components used by specific host microorganisms, while preparations combining suitably chosen microorganisms and the substrate for them are called synbiotics.

The latest performance data

In 2026 Frontiers in Nutrition published an analysis of probiotic use and the physical fitness of healthy people. The authors included 21 studies with a total of 685 participants. Across the material, probiotic use was associated with a small-to-moderate difference in fitness outcomes in favour of the groups receiving a probiotic. A clearer signal was obtained for parameters related to endurance exercise.

The most consistent effect was noted at doses of 10⁹ to 10¹¹ CFU per day. Beneficial results were obtained for both single- and multi-strain preparations, with the effect of the latter somewhat larger. Overall certainty of evidence was rated moderate. The studies differed, however, in the strains, doses, duration of supplementation and fitness tests used; study groups were often small and interventions short.

An athlete's gut day to day

The result may be consistent with the premise that an athlete's digestive tract faces several additional burdens. High energy demand encourages frequent use of gels, carbohydrate drinks and bars, and with low dietary variety this may be accompanied by lower fibre and plant-food intake. The gut is additionally strained by intense exercise, dehydration, high temperature, competition stress, sleep deprivation and travel.

At the same time, large amounts of fibre or carbohydrate during exercise can worsen gastrointestinal tolerance, so their intake must be matched to training and increased gradually.

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Melatonin provides one of the most important signals about the time of day. Its action includes regulating the circadian rhythm and processes related to the body's response to exercise.

Melatonin and the circadian rhythm

Melatonin is a hormone produced mainly by the pineal gland, a small gland in the brain. It is formed from tryptophan — an amino acid present in dietary proteins — and one intermediate step in this process is serotonin.

Its production is strongly time-of-day dependent. Information about light reaches the main biological clock in the hypothalamus from the retina, and then the pineal gland. During the light part of the day melatonin secretion remains low, whereas after dark it begins to rise. The highest values usually appear during the biological night, after which the level falls again towards morning. It is not, however, simply a substance that "switches off" the brain and induces sleep.

Consequences of disturbed melatonin secretion

Melatonin disturbances usually concern not the presence of melatonin itself but its amount, timing of secretion or the size of the nocturnal rise. When the evening rise appears too late, is weakened or shifted by light, night work or a change of time zone, the biological clock may stop matching the actual hours of sleep and activity. This may be accompanied by harder falling asleep, a shift in sleep timing, more frequent awakenings and sleepiness during time meant for activity.

This does not mean, however, that every sleep problem results from a "melatonin deficiency". Sleep also depends on time spent awake, stress, physical activity, stimulants, medications, illnesses and individual features of the circadian rhythm. Shifts in the melatonin rhythm may be accompanied by shifts in the cortisol and body-temperature rhythms, so not all consequences of a disturbed rhythm can be attributed solely to reduced melatonin production.

Melatonin, performance and recovery

A 2026 publication combined the results of 19 studies comparing melatonin with placebo in a total of 266 physically active people. In 13 experiments the participants were competitive or professional athletes, mainly footballers and volleyball players. Doses of 3 to 10 mg were used; 14 studies assessed a single dose, while five used melatonin for several days or up to four weeks.

After pooling the results, a moderate difference in favour of melatonin was found in endurance tests and a small difference in explosive power. The more favourable result concerned mainly time-to-exhaustion. In trials involving covering a set distance as fast as possible no clear difference was confirmed, and no consistent improvement in speed or maximal muscle strength was shown.

In seven studies on creatine kinase — an enzyme whose blood level can rise after intense exercise and muscle damage — lower values were found after melatonin than after placebo. A more favourable picture was obtained when melatonin was taken in the evening and exercise performed more than six hours later. These relationships should not, however, be treated as an established supplementation scheme — they were based on few studies, and most participants were men.

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Coenzyme Q10 takes part in reactions essential to life. In recent years its role in regulating glucose metabolism has been analysed, especially in people with metabolic disorders.

Disturbances of glycaemic control

After a meal, glucose passes from the digestive tract into the blood, and the pancreas secretes insulin, which helps cells use it and limits an excessive rise in blood glucose. Proper glycaemic control means keeping blood glucose within a range the body can handle efficiently. Disturbances can appear when tissues respond more weakly to insulin, the pancreas does not produce enough of it, or both mechanisms occur at once.

The most commonly used markers include fasting glucose and glycated haemoglobin (HbA1c), which reflects the average exposure of red blood cells to glucose over the preceding roughly 2–3 months. An oral glucose tolerance test is also used. From glucose and insulin levels the HOMA-IR index — a model estimate of insulin resistance — is calculated, though it alone does not serve to diagnose diabetes.

Coenzyme Q10 – properties and sources

Coenzyme Q10 (CoQ10), also called ubiquinone, is a fat-soluble compound. It is not a vitamin in the strict sense, because humans do not have to obtain all the needed amount from food. A large part of CoQ10 is found in the mitochondria, where it participates in electron transport in the respiratory chain linked to the formation of ATP. It occurs in two interconverting forms: oxidised (ubiquinone) and reduced (ubiquinol).

CoQ10 is produced mainly in the body, but small amounts come from the diet — richer sources are offal, meat and fish. A typical diet usually provides only a few milligrams a day, whereas supplementation studies often use doses in the hundreds of milligrams. Because CoQ10 dissolves in fat, its absorption depends among others on the form of the preparation and the presence of fat in the digestive tract.

CoQ10 and markers of glycaemic control

A 2026 paper assessed whether coenzyme Q10 supplementation was associated with changes in markers of glycaemic control. From 452 records found, eight papers published between 2016 and 2023 were included. The populations covered included, among others, people with type 2 diabetes, obesity or overweight, metabolic syndrome, polycystic ovary syndrome and chronic kidney disease.

Mean CoQ10 doses ranged from about 110 to 376.6 mg per day, and supplementation lasted about 8–15 weeks. Lower fasting glucose by 5.04 mg/dl, HbA1c by 0.17 percentage points, HOMA-IR by 0.72 and insulin by 1.32 µIU/ml were observed in the groups receiving CoQ10. With a different approach to analysing the data, a significant difference was confirmed for fasting glucose, whereas for HbA1c, HOMA-IR and insulin no significant changes were shown.

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