Anise: benefits and therapeutic properties

Anise (Pimpinella anisum L., family Apiaceae) is an aromatic annual herb native to the eastern Mediterranean region and western Asia and cultivated in many regions. the fruit is commonly known as anise, which when ripe and dried is the popular spice. Anise has a sweet and aromatic flavor similar to licorice.

In the food industry, it acts as an antioxidant and preservative.

Depending on the region of cultivation and the method of extraction, the main constituents of anise essential oil are generally trans-anethole (85%-95%), γ-imachalene (0.4%-8.2%), methylcavicol or estragole (0.5%-5.0%), p-anisaldehyde (0%-5%) and pseudoisoisoeugenol-2-methylbutyrate (1.3%-3.0%)

In ancient times, aniseed was used to promote childbirth and stimulate milk production, and it continues to be recommended for various illnesses in folk medicines. Mainly due to the presence of trans-anethole, the fruit and essential oil are used in traditional therapies, for example, to relieve cough, respiratory congestion, migraine, gastrointestinal disorders, and colic; to treat skin infections; as a tranquilizer and aphrodisiac; and to improve lactation.

Recent efforts are being made to understand the efficacy of aniseed for diabetes, dysmenorrhea, and menopausal hot flashes, as well as to clarify its antioxidant, anti-inflammatory, and antimicrobial properties.

This narrative review summarizes studies on humans and the potential health benefits of aniseed and highlights areas for future research.

Human studies evaluating the influence of aniseed on various health conditions are few.

The reported RCT studies were mostly conducted in one geographical region (8 reports from Iran), small in size (n = 20-47 subjects) and short in duration (4-6 weeks). The quality of the studies varied because some were not adequately blinded and statistical comparisons of results between treatment and control groups were not always reported.

Nonetheless, these studies provide preliminary evidence of anise’s potential actions in modulating the signs and symptoms of diabetes, gastrointestinal disorders, sinusitis, migraine, and women’s disorders.

Diabetes

Specifically, anise powder (5 g/d) was administered to subjects (n = 20) with type 2 diabetes mellitus for 60 days.

This daily intake of anise powder is considerably higher than the typical consumption of several servings of anise-containing foods. Compared with baseline values, anise administration was associated with a significant reduction in fasting blood glucose concentrations and blood levels of total cholesterol and triglycerides.

In addition, blood levels of oxidative stress biomarkers decreased and those of antioxidant factors increased. In contrast, in control group subjects, compared with baseline, fasting blood glucose increased and total cholesterol and triglyceride levels remained unchanged at 60 days.

Dyspepsia and inflammatory bowel syndrome

In another investigation, anise powder (9 g/d) was administered to patients with functional dyspepsia for 4 weeks. Compared with placebo, patients who received anise reported significantly less epigastric discomfort and bloating, epigastric and postprandial pain, and early satiety.

The prevalence of nausea and vomiting did not change.

In addition, in subjects given anise powder, quality of life was significantly improved based on increased social and physical functions, general health, and vitality.

Further mechanistic insights are, however, needed, such as how anise affects gastric emptying rate and antrum contractions, regulation of gastrointestinal motility, modulation of gastric mucosal inflammatory factors, and prevalence of Helicobacter pylori infection.

Anise oil in enteric capsule form was administered orally (600 mg/d) to subjects (n = 38) with irritable bowel syndrome (IBS) for 4 weeks in a 3-arm, double-blind, placebo-controlled study.

Detailed descriptions of the demographics and basic characteristics of the participants were provided.

Compared with the placebo group (n = 37), patients administered the oil reported significantly lower rates of diarrhea, bloating, reflux, severity of constipation, and abdominal pain, improvements that continued for an additional 2-week follow-up period after dosing was discontinued. Seventy-five percent of patients had no symptoms of IBS at the end of the 4-week treatment period, compared with 35% of control subjects (P .001).<

In addition, anise oil intake resulted in a significant decrease in symptoms of mild to moderate depression in subjects with IBS and a significant increase in quality of life scores.

Interestingly, in this study anise oil treatment was superior in reducing IBS symptoms compared to subjects in the third arm (n = 33) who were given Colpermin IBS relief capsules (containing 566 mg peppermint oil).

This superior performance of anise oil is significant because peppermint essential oil is a commonly recommended remedy that is effective and well tolerated in the short-term management of irritable bowel syndrome, compares favorably with other potential treatments for irritable bowel syndrome, and consistently demonstrates benefits in the treatment of nonulcerative dyspepsia. Therefore, further characterization of the effectiveness of aniseed in relieving irritable bowel syndrome is warranted.

Migraine and sinusitis

Anise oil incorporated into a cream was applied for 6 weeks to the temporal and forehead regions of individuals (n = 22) suffering from migraine.

Compared with users of a placebo cream, treatment with the cream containing aniseed oil significantly reduced the frequency and duration of attacks, although the severity of the attacks was not lessened.

In another study, subjects (n = 26) with chronic rhinosinusitis without polyps28 were instructed to apply nasal drops containing 200 μg of an aqueous extract of anise in almond oil to each nostril every 12 hours for 4 weeks.

Another group of patients was given the corticosteroid drug fluticasone nasally. When the results of anise extract treatment and fluticasone dosing were examined, both anise extract and fluticasone significantly improved sinonasal symptoms and significantly reduced sinonasal sinus mucosal inflammation as measured by computed tomography.

Interestingly, when these two groups were compared, anise-containing drops were significantly more effective than fluticasone in reducing rhinologic symptoms.

Hot flashes and premenopausal syndrome

Alcoholic extracts of anise powder were analyzed in 2 studies. In one study, the extract (990 mg/d) was administered for 4 weeks to subjects (n = 36) suffering from menopausal hot flashes.

Compared with controls, there was a significant reduction in the severity and frequency of hot flashes. Notably, this beneficial response continued for another 2 weeks after surgery.

Future studies should compare the action of these traditional medicines with the efficacy of accepted hormone replacement therapies and clarify possible mediators of changes in the intensity and severity of hot flashes, such as levels of estradiol, estrone, follicle-stimulating hormone, and sex hormone-binding globulin. In another study, an alcohol extract (330 mg/d) was administered orally to college-aged women (n = 35) for 7 days before and 3 days after each of 2 menstrual cycles.

Compared with placebo, anise treatment significantly reduced the symptoms and intensity of premenopausal syndrome. As was noted in a recent review of the effects of anise on female disorders, most clinical studies have evaluated anise in combination with different plant materials.

Therefore, human investigations examining the individual efficacy of anise, its oil, and its extracts on various female conditions, such as pain after childbirth, menstrual pain, polycystic ovary syndrome, hot flashes, and menopause-related depression, are needed.

Infant transition to breastfeeding

Finally, in a previously unpublished study of premature infants in Belgium, infants were exposed to an anise-containing olfactory stimulus 10 minutes before test tube meals to determine whether this brief stimulus would lead to a faster transition to satisfactory maternal breastfeeding. Compared with controls, there was a trend (P<.12) toward shorter duration of tube feeding and subsequent duration of hospitalization.

In a post hoc analysis of hospitalized infants weighing 2000 g or more, the hospital stay of those given the olfactory stimulus was significantly shorter than that of controls. It should be noted that, in these different clinical trials, the doses and duration of treatments with anise, anise oil, and extract were not associated with significant adverse effects.

However, caution is needed in the medicinal use of high amounts of aniseed for sensitive individuals, such as pregnant and lactating women and infants. Therefore, to provide evidence-based recommendations, high-quality clinical studies are needed that elucidate the bioavailability of phytochemicals consumed in anise powder, oil, and extracts; characterize physiological responses associated with dose and duration of anise intake; and better illuminate potential adverse effects for individuals with different health conditions.