Composition for promoting or improving renal function

Abstract

The present invention relates to a method and means for promoting or improving renal function. Specifically, the present invention relates to a composition for promoting or improving renal function, the composition containing turmeric extract as an active ingredient.

Description

Composition for promoting or improving renal function

[0001] The present invention relates to a composition for promoting or improving renal function, and in particular to a composition for promoting or improving renal function containing a turmeric extract.

[0002] The kidneys are involved in regulating various physiological functions, such as excreting waste products from the blood, reabsorbing nutrients necessary for the body from among the excreted substances, maintaining a constant body fluid level by excreting excess water and salt, and producing hormones involved in maintaining homeostasis. It is known that these regulatory functions of the kidneys are impaired due to renal disease or renal impairment, as well as aging and an irregular lifestyle, resulting in symptoms such as edema, frequent urination, and fatigue.

[0003] There have been several reports on the relationship between turmeric extract and kidney damage. For example, it has been reported that carbon tetrachloride-induced kidney damage was suppressed in rats that received oral administration of a turmeric hot water extract in combination with intraperitoneal administration of a calcium blocker (Non-Patent Document 1). It has also been reported that kidney damage was suppressed in a diabetic nephropathy model rat that received bisacron, a component of turmeric (Non-Patent Document 2), and that high-fat diet-induced kidney damage was suppressed in rats that received curcumin, a component of turmeric (Non-Patent Document 3).

[0004] In addition, the effect of aqueous turmeric extract on isoniazid (INH)- and rifampicin (RIF)-induced renal damage has been investigated, and it has been reported that the aqueous turmeric extract inhibited the rise in creatinine levels in mice with induced renal damage, while there was no change in creatinine levels in healthy mice (Non-Patent Document 4). Similarly, it has been reported that the effect of methanolic turmeric extract on acetaminophen-induced renal damage did not change creatinine levels in healthy rats (Non-Patent Document 5), that the effect of ethyl acetate extract of turmeric on ethanol-induced renal damage did not change creatinine levels in healthy rats (Non-Patent Document 6), and that the effect of curcumin (a component of turmeric) on potassium bromate (KBrO3)-induced renal damage did not change creatinine levels in healthy rats (Non-Patent Document 7).

[0005] Uchendu, IK et al., Pak J Pharm Sci. 33(5):2059-2065, 2020. Yang, F. et al., Hum Exp Toxicol. 41:9603271221143713, 2022. Ding, X. et al., Int J Mol Sci. 23(13):7395, 2022.Thuawaini, MM et al., Asian J Pharm Clin Res. 12(3):293-298, 2019.Khoursandi, LS et al., DARU Journal of Pharmaceutical Sciences 16(3):155-159, 2008.Eteng, OE et al., Asian Journal of Natural Product Biochemistry 18(1), 2020. Akomolafe, SF et al., Biol Trace Elem Res. 199(1):197-204, 2021.

[0006] It has been reported that ingestion of turmeric extract or turmeric-derived components improves creatinine levels in patients with drug-induced kidney damage (pathological level), but there have been no reports on the effects of ingestion of turmeric extract or turmeric-derived components on the kidneys in healthy patients, particularly in humans.

[0007] Therefore, an object of the present invention is to provide means and methods for promoting or improving renal function (eg, serum creatinine levels) in healthy subjects, particularly humans without renal disease or impairment.

[0008] In the course of intensive research into the effects of turmeric extract, the present inventors discovered that turmeric extract has the effect of suppressing an increase in serum creatinine levels in humans with normal renal function, and gained the knowledge that turmeric extract can promote or improve renal function, and ultimately prevent a decline in renal function, leading to the completion of the present invention.

[0009] Therefore, the present invention encompasses, for example, the following: [1] A composition for promoting or improving renal function, comprising a turmeric extract as an active ingredient. [2] The composition according to [1], wherein the composition consists solely of a turmeric extract as an active ingredient. [3] The composition according to [1] or [2], wherein the turmeric extract comprises a turmeric extract obtained with at least one extraction solvent selected from the group consisting of water and hydrophilic organic solvents. [4] The composition according to [1] or [2], wherein the turmeric extract comprises a mixture of a turmeric extract obtained by extraction with water and a turmeric extract obtained by extraction with supercritical carbon dioxide. [5] The composition according to any of [1] to [4], wherein the turmeric extract contains at least one of turmeronol A, turmeronol B, and bisacron. [6] The composition according to [5], wherein the total amount of turmeronol A and turmeronol B per daily intake is 100 μg or more. [7] The composition according to any of [1] to [6], wherein the composition is administered to a human without renal disease or impairment.

[0010] [8] Use of a turmeric extract for producing a composition for promoting or improving renal function. [9] A method for promoting or improving renal function in a subject, comprising administering a turmeric extract to a subject in whom prevention of decline in renal function is desired, and promoting or improving renal function in the subject.

[10] The method according to [9], wherein the subject is a human without renal disease or renal impairment.

[11] A turmeric extract for use in promoting or improving renal function.

[0011] According to one or more embodiments of the present invention, there is provided a composition for promoting or improving renal function, particularly a composition for administration to a human without renal disease or impairment. The composition of the present invention is useful for promoting or improving renal function and preventing the decline of renal function.

[0012] 1 is a graph showing the change in creatinine levels before and after 4, 8, and 12 weeks of turmeric extract intake in the control group and placebo group. ** indicates p<0.01 and * indicates p<0.05 compared to the placebo group.

[0013] This specification includes the disclosure of Japanese Patent Application No. 2023-149906, filed September 15, 2023, from which this application claims priority.

[0014] The present invention is based on the finding that administration or ingestion of turmeric extract can promote or improve renal function. Specifically, it was observed that ingestion of turmeric extract inhibited increases in serum creatinine levels in humans with normal renal function, and this is based on the experimental results that ingestion of turmeric extract promotes or improves renal function. It is known that kidneys are difficult to recover once they have deteriorated due to renal disease or renal impairment, and it is important to maintain normal renal function and prevent its decline.

[0015] Therefore, in one aspect, the present invention provides a composition for promoting or improving kidney function, which contains turmeric extract as an active ingredient.

[0016] In this specification, renal function refers to physiological functions in the living body in which the kidneys are involved, and includes, but is not limited to, functions such as excreting waste products in the blood from the body (excretion of uremic toxins), absorbing nutrients necessary for the body from the excreted substances back into the body (reabsorption in the renal tubules), maintaining constant body fluids by excreting excess water and salt (adjusting the water balance, electrolyte balance, and pH of body fluids), and producing hormones involved in maintaining homeostasis.

[0017] Renal function can be assessed by any method known in the art. For example, serum creatinine (Cr) (blood creatinine and plasma creatinine are known to have equivalent creatinine values) is filtered through the glomeruli of the kidney and excreted in urine. However, as renal function declines, the amount excreted in urine decreases, resulting in the accumulation of creatinine in the blood. This leads to an increase in serum creatinine levels. Therefore, measurement of serum creatinine levels is widely used as a renal function test. Normal serum creatinine levels are considered to be 1.2 mg / dL or less for men and 1.0 mg / dL or less for women. Creatinine clearance (CCr), a test that measures the amount of blood filtered through the glomeruli, is also known and is an indicator of the actual amount of creatinine excreted by the kidney. Daily urine is collected (24-hour urine collection), and the amount of creatinine excreted is measured and calculated based on serum creatinine. As kidney function deteriorates, the amount filtered decreases, and so does the creatinine clearance value. Normal values ​​are around 100-120 ml / min. Furthermore, there is also a known test to measure the amount of nitrogen in the blood as blood urea nitrogen (BUN). Urea nitrogen is a waste product produced after protein is used. Normally, it is filtered by the glomeruli of the kidneys and excreted in the urine, but when kidney function declines, it cannot be completely filtered and accumulates in the blood, causing the blood urea nitrogen level to rise. The normal value for blood urea nitrogen is below 20 mg / dl.

[0018] Promoting or improving renal function means promoting renal function, protecting renal function, maintaining renal function within the normal range, inhibiting decline in renal function, or improving renal function that is within the normal range but has declined, compared to when turmeric extract is not administered or ingested. Therefore, in the present invention, the subject includes any subject for whom promotion or improvement of renal function is desired (e.g., subjects with renal disease or renal impairment, subjects at risk of developing renal disease or renal impairment, subjects without renal disease or renal impairment, etc.). Renal function can deteriorate or decline due to renal disease or renal impairment, but even healthy subjects (i.e., subjects without renal disease or renal impairment) can experience decline due to aging, diet, lack of sleep, etc. Renal function can also decline due to other diseases (e.g., diabetes) or treatment for other diseases. In the present invention, administration of turmeric extract promotes or improves renal function and prevents decline or worsening of renal function, even in subjects with normal renal function, particularly in subjects without renal disease or renal impairment. For example, in subjects with normal renal function, the eGFR value, which is calculated based on creatinine levels and correction factors such as age, is ≥ 60 mL / min / 1.73m 2 It includes objects where:

[0019] <Composition Containing Turmeric Extract> The composition of the present invention contains turmeric extract. In the present invention, turmeric extract refers to an extract (turmeric extract) of a plant material derived from a plant of the genus Curcuma in the Zingiberaceae family, using an extraction solvent. Turmeric extract is not limited to solvent extracts obtained by extraction with an extraction solvent, but also includes solvent extracts that have been further fractionated and purified by column chromatography or the like. The turmeric extract used in the present invention can be in the form of an extract liquid after the extraction procedure (including fractionation and purification if fractionation and purification is performed), a concentrate obtained by partially removing the solvent from the extract liquid, or a dried product obtained by removing the solvent from the extract liquid. The solvent can be removed from the extract by volatilizing the solvent by heating and / or reducing pressure, etc. The heating and pressure reduction methods are not particularly limited, and for example, conventionally known methods can be used.

[0020] Examples of the plant material include the rhizomes of plants of the genus Curcuma in the Zingiberaceae family, such as Curcuma longa (turmeric), Curcuma aromatica, Curcuma zedoaria, Curcuma phaeocaulis, Curcuma kwangsiensis, Curcuma wenyujin, and / or Curcuma xanthorrhiza. The rhizomes of Curcuma longa are particularly preferred. The rhizomes may be collected from the ground, and an appropriate portion of the rhizome may be used intact, cut to an appropriate size or shape, or pulverized. These plant materials may be appropriately dried.

[0021] The extraction solvent can be at least one selected from the group consisting of water and hydrophilic organic solvents. The at least one extraction solvent selected from the group consisting of water and hydrophilic organic solvents can be water, a hydrophilic organic solvent, or a mixed solvent of water and a hydrophilic organic solvent. The hydrophilic organic solvent can also be a mixed solvent of multiple hydrophilic organic solvents. "Water" also includes hot water. Hot water, for example, can be hot water at 95°C or higher. The hydrophilic organic solvent can include at least one alcohol (or a mixed solvent of multiple alcohols). The alcohol is not particularly limited, but ethanol is preferred. When a mixed solvent of alcohol and water is used as the extraction solvent, the mixing ratio is not particularly limited, but is preferably in the range of 10:90 to 90:10 by weight, and more preferably 20:80 to 50:50 by weight. Supercritical carbon dioxide can also be used as the extraction solvent.

[0022] The method for extracting turmeric extract from plant materials is not particularly limited, and any extraction method commonly used in the art can be employed.

[0023] In the present invention, the turmeric extract may contain one type of turmeric extract, or may contain two or more types of turmeric extracts obtained using different extraction solvents and / or extraction methods. In one embodiment, the turmeric extract comprises a mixture of a turmeric extract obtained using at least one extracting solvent selected from the group consisting of water and a hydrophilic organic solvent, and a turmeric extract obtained using supercritical carbon dioxide, for example, a mixture of a turmeric extract obtained by extraction with water and a turmeric extract obtained by extraction with supercritical carbon dioxide. The ratio of each extract in the mixture is not particularly limited, and may be, for example, a weight ratio of 1:0.01 to 1:1.

[0024] In a preferred embodiment, the turmeric extract comprises at least one of an extract with water, such as hot water, and an extract with supercritical carbon dioxide.

[0025] The turmeric extract used in the present invention contains at least one of turmeronol A, turmeronol B, and bisacronol.

[0026] Turmeronol A and turmeronol B are compounds each having the following planar structure.

[0027]

[0028]

[0029] In the present invention, turmeronol A and turmeronol B each have the above-mentioned planar structure, and may be any optical isomer or a mixture of multiple optical isomers.

[0030] It is known that the configuration of the 6-carbon atom in the partial structure of 2-methyl-2-hepten-4-one in natural products isolated from turmeric extracts, such as turmeronol A and turmeronol B, is S. However, in the present invention, turmeronol A and turmeronol B may have the above-mentioned planar structure, and the configuration may be S, R, or a mixture of S and R.

[0031] In the present invention, bisacron is a compound having the following planar structure: Bisacron has an asymmetric carbon at the position indicated by the * mark in the planar structural formula and may contain multiple optical isomers, but in the present invention, bisacron may be any optical isomer or a mixture of two or more optical isomers.

[0032]

[0033] The turmeric extract may be processed by a conventional method such as drying, powdering, granulation, or solution.

[0034] <Composition of the Present Invention> One aspect of the composition of the present invention relates to a composition for promoting or improving renal function, containing the turmeric extract as an active ingredient. By administering the composition of the present invention according to this aspect to a subject such as a human, renal function in the subject can be promoted or improved. Here, the active ingredient is ingested or administered in an amount effective for promoting or improving renal function. Oral or nasal administration is preferred as the route of administration, with oral administration being particularly preferred. The composition of the present invention can promote or improve renal function by suppressing an increase in serum creatinine levels.

[0035] The composition of the present invention may be in the form of a pharmaceutical, food or drink, feed, food additive, feed additive, etc., and is more preferably a pharmaceutical or food or drink. Food and drink products also include those in the form of functional foods, foods for specified health uses, nutritional supplements, etc. The composition of the present invention is preferably in the form of a composition that is ingested or administered orally or nasally, and more preferably in the form of a composition that is ingested or administered orally.

[0036] The content of the turmeric extract in the composition of the present invention is such that the total amount of turmeronol A and turmeronol B is 100 μg or more per daily intake or dosage of the composition of the present invention, preferably per daily intake or dosage for one human, particularly one adult, and / or the amount of turmeronol A is 17 μg or more, preferably 28 μg or more, more preferably 43 μg or more, even more preferably 57 μg or more, most preferably 80 μg or more, for example 100 μg; In order to effectively promote or improve renal function, it is preferable to contain 5 μg or more, preferably 8 μg or more, more preferably 12 μg or more, even more preferably 16 μg or more, and most preferably 20 μg or more, e.g., 100 μg, of turmeronol B and / or 80 μg or more, preferably 133 μg or more, more preferably 200 μg or more, even more preferably 267 μg or more, and most preferably 360 μg or more, e.g., 400 μg, of bisacronol. There is no particular upper limit to the content of the turmeric extract or each component. Here, the "daily intake or administration amount" refers to a typical amount of 0.1 g to 500 g of the composition of the present invention when taken or administered orally or nasally, preferably orally. The composition of the present invention may be taken or administered continuously or as needed.

[0037] The composition of the present invention containing the turmeric extract as an active ingredient may be the turmeric extract itself, or it may be a composition containing the turmeric extract and at least one other ingredient. When the composition of the present invention contains the turmeric extract and at least one other ingredient, it may be a composition obtained by mixing the turmeric extract and at least one other ingredient, a composition obtained by formulating the turmeric extract and at least one other ingredient by an appropriate means, or a composition obtained by mixing a composition obtained by formulating the turmeric extract and at least one other ingredient with other ingredients. In one embodiment, the composition of the present invention is a composition consisting solely of turmeric extract as an active ingredient. "Consisting solely of turmeric extract as an active ingredient" means that the active ingredient exhibiting the desired activity (enhancement or improvement of renal function) is turmeric extract alone, and no other active ingredients are contained. However, components other than the active ingredient, such as carriers and excipients, may also be contained in the composition of the present invention.

[0038] The form of the composition of the present invention is not particularly limited, and may be, for example, any of liquid, fluid, gel, semi-solid, and solid forms.

[0039] The at least one other component that may be contained in the composition of the present invention is not particularly limited, but preferably includes a component that is acceptable in the final form of a pharmaceutical, food or drink, nutritional supplement, supplement, feed, food additive, feed additive, etc., and that can be orally ingested.

[0040] Such other ingredients include, for example, sweeteners, acidulants, vitamins, minerals, thickeners, emulsifiers, antioxidants, water, etc. Furthermore, colorants, flavorings, preservatives, antiseptics, fungicides, and other physiologically active substances may also be added as necessary.

[0041] Examples of sweeteners include monosaccharides and disaccharides such as glucose, fructose, sucrose, lactose, maltose, palatinose, trehalose, and xylose, isomerized sugars (glucose-fructose corn syrup, fructose-glucose corn syrup, mixed sugar isomerized sugars, etc.), sugar alcohols (erythritol, xylitol, lactitol, palatinit, sorbitol, reduced starch syrup, etc.), honey, and high-intensity sweeteners (sucralose, acesulfame potassium, thaumatin, stevia, aspartame, etc.).

[0042] The acidulant may be citric acid, malic acid, gluconic acid, tartaric acid, lactic acid, phosphoric acid, or salts thereof, and one or more of these may be used.

[0043] Vitamins include vitamin A, vitamin B1, vitamin B2, vitamin B6, vitamin E, niacin, inositol, etc.

[0044] Examples of minerals include calcium, magnesium, zinc, and iron.

[0045] Examples of thickeners include carrageenan, gellan gum, xanthan gum, gum arabic, tamarind gum, guar gum, locust bean gum, karaya gum, agar, gelatin, pectin, soybean polysaccharides, and carboxymethylcellulose (CMC).

[0046] Examples of emulsifiers include glycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, lecithin, plant sterols, and saponin.

[0047] Examples of antioxidants include vitamin C, tocopherol (vitamin E), enzyme-treated rutin, etc. The other components can be appropriately blended in amounts within the ranges that would normally be used by those skilled in the art in compositions such as foods and beverages, pharmaceuticals, etc.

[0048] The form of a composition prepared by appropriate means from the composition of the present invention and at least one other ingredient may be in the form of a solid composition such as powder, granules, capsules, tablets (including coated tablets such as sugar-coated tablets or multi-layer tablets, orally disintegrating tablets, chewable tablets, etc.), or in the form of a liquid composition such as a solution.

[0049] Furthermore, the composition of the present invention is relatively safe and can be easily taken continuously over a long period of time. Therefore, the composition of the present invention can be preferably used in foods and beverages, nutritional supplements, dietary supplements, and feed. The composition of the present invention has the above-mentioned functions or activities, and also contains a turmeric extract that has been conventionally taken, making it relatively safe. Furthermore, it can be added to various foods and beverages and taken continuously, and is expected to exert the desired functions or effects.

[0050] The composition of the present invention is preferably a composition to be taken continuously, specifically, a composition to be taken continuously once or twice a day, preferably for 4 weeks or more, more preferably for 8 weeks or more, and most preferably for 12 weeks or more.

[0051] <Method for Promoting or Improving Renal Function> A further aspect of the present invention relates to a method for promoting or improving renal function, comprising: administering the turmeric extract to a subject; and promoting or improving renal function in the subject.

[0052] The turmeric extract used in the method according to this embodiment may be in the form of the composition of the present invention as described above.

[0053] The subject of the method according to this embodiment is a subject in whom prevention of decline in renal function is desired, typically a healthy human, i.e., a human without renal disease or renal impairment, but may also be a mammal other than a human. Here, a human without renal disease or renal impairment is a human whose renal function has been confirmed to be normal at least before the start of administration of the turmeric extract.

[0054] In the method according to this embodiment, the route of administration is preferably oral or nasal administration, with oral administration being particularly preferred.

[0055] In the method according to this embodiment, the dose of the turmeric extract administered to a subject is not particularly limited as long as it is an amount effective for promoting or improving renal function. For example, if the subject is an adult, the turmeric extract is preferably administered to an adult per day, based on the components contained therein, so that the total amount of turmeronol A and turmeronol B is 100 μg or more, and / or turmeronol A is 17 μg or more, preferably 28 μg or more, more preferably 43 μg or more, even more preferably 57 μg or more, most preferably 80 μg or more, for example 100 μg, and / or turmeronol B is 5 μg or more, preferably 8 μg or more, more preferably 12 μg or more, even more preferably 16 μg or more, most preferably 20 μg or more, for example 100 μg, and / or bisacrolone is 80 μg or more, preferably 133 μg or more, more preferably 200 μg or more, even more preferably 267 μg or more, most preferably 360 μg or more, for example 400 μg.

[0056] The amount of administration or intake of the composition of the present invention varies depending on the age and weight of the subject, the route of administration / intake, the frequency of administration / intake, the purpose of administration, etc., and can be varied widely at the discretion of those skilled in the art so as to achieve the desired effect. The proportion of turmeric extract in the composition is not particularly limited and may be appropriately adjusted depending on the ease of production, the preferred daily dose, etc. Because turmeric extract is relatively safe, the intake amount can be further increased. The daily intake amount may be taken in one dose or in several divided doses. The frequency of administration or intake is also not particularly limited and can be appropriately selected depending on various conditions such as the route of administration / intake, the age and weight of the subject, and the desired effect.

[0057] [Reference Examples] (1) Methods for Preparing Turmeric Extracts Turmeric extracts were prepared by water extraction and supercritical gas extraction. In the water extraction method, turmeric rhizome parts were extracted with water (including hot water), and the resulting extract was then dried under reduced pressure to remove moisture. In the supercritical gas extraction method, turmeric rhizome parts were contacted with supercritical carbon dioxide, and the extracted components were mixed with vegetable oil. In the following examples, turmeric extracts prepared by each extraction method were mixed at a weight ratio of 8:1.

[0058] (2) Test Food Containing Turmeric Extract The test food is a soft capsule containing the turmeric extract prepared in (1) at 100 μg of turmeronol A (TA), 100 μg of turmeronol B (TB), and 400 μg of bisacronol per two capsules. The test food is a soft capsule made from vegetable oil, gelatin, glycerin, emulsifier (soybean-derived), and beeswax as raw materials. The placebo food is a soft capsule of the above test food that does not contain turmeric extract.

[0059] (3) Amounts of Turmeronol A, Turmeronol B, and Bisacron in Turmeric Extract The amounts of turmeronol A, turmeronol B, and bisacron in the turmeric extract were measured using HPLC as follows. The amounts of turmeronol A, turmeronol B, and bisacron per gram of turmeric extract were confirmed to be 724 μg, 578 μg, and 2182 μg, respectively.

[0060] Analysis of Turmeronol A Turmeric extract was weighed, water and ethyl acetate were added, and the resulting supernatant was centrifuged. The ethyl acetate was then removed under reduced pressure and dissolved in acetonitrile. The resulting liquid was used as the measurement sample and subjected to HPLC. HPLC was performed under the following conditions: Column: L-column ODS 5 μm (4.6 mm φ × 250 mm) Mobile phase: 48% acetonitrile (20 min) → 100% acetonitrile (5 min) → 48% acetonitrile (10 min) Flow rate: 1.0 mL / min Column temperature: 40°C Detection wavelength: 238 nm

[0061] Analysis of Turmeronol B Turmeric extract was weighed, water and ethyl acetate were added, and the mixture was centrifuged. The ethyl acetate was removed from the resulting supernatant by vacuum distillation, and the resulting solution was dissolved in acetonitrile. The resulting solution was used as the measurement sample and subjected to HPLC. HPLC was performed under the following conditions: Column: COSMOSIL 5PYE Packed Column (4.6 mm φ x 150 mm) Mobile phase: 57% methanol (30 min) ⇒ 100% methanol (5 min) ⇒ 57% methanol (15 min) Flow rate: 1.0 mL / min Column temperature: 40°C Detection wavelength: 238 nm

[0062] Analysis of Bisacron The turmeric extract was weighed, water and ethyl acetate were added, and the mixture was centrifuged to obtain a supernatant. The ethyl acetate was then removed under reduced pressure from the resulting supernatant, and the mixture was dissolved in acetonitrile. The resulting liquid was used as a measurement sample and subjected to HPLC. HPLC was performed under the following conditions: Column: Wakopak Navi C18-5 (4.6 mm φ x 250 mm) Mobile phase: 30% acetonitrile (20 minutes) ⇒ 20% acetonitrile (5 minutes) ⇒ 80% acetonitrile (10 minutes) Flow rate: 0.7 mL / min Column temperature: 50°C Detection wavelength: 240 nm

[0063] [Example 1] Study of serum creatinine levels Healthy male and female subjects aged 40 to 69 (subjects confirmed by a physician to have no abnormalities in renal function) were randomly assigned to two groups (placebo group: n=41, turmeric extract group: n=39) and under double-blind conditions, they were asked to take two tablets of a test food containing turmeric extract or a placebo food not containing the extract once daily before dinner for 12 weeks. Serum creatinine levels were measured before ingestion of the test food (week 0) and after 4, 8, and 12 weeks of ingestion.

[0064] Figure 1 shows the change in creatinine levels from before intake of the test food (week 0) to 4, 8, and 12 weeks later. Figure 1 shows the mean ± SEM (placebo group: n=41, turmeric extract group: n=39), with ** indicating p<0.01 and * indicating p<0.05 compared to the placebo group. As shown in Figure 1, creatinine levels in the turmeric extract group were significantly lower at weeks 4 and 12 compared to the placebo group. These results demonstrate that intake of turmeric extract promotes or improves renal function in healthy subjects.

[0065] All patents, patent applications and publications cited herein are hereby incorporated by reference in their entirety.

Claims

1. A composition for promoting or improving renal function, comprising turmeric extract as an active ingredient.

2. The composition of claim 1, wherein said composition consists solely of turmeric extract as an active ingredient.

3. The composition of claim 1, wherein the turmeric extract comprises an extract of turmeric with at least one extraction solvent selected from the group consisting of water and hydrophilic organic solvents.

4. The composition according to claim 1, wherein the turmeric extract comprises a mixture of a turmeric extract obtained by extraction with water and a turmeric extract obtained by extraction with supercritical carbon dioxide.

5. The composition of claim 1, wherein the turmeric extract contains at least one of turmeronol A, turmeronol B and bisacron.

6. The composition described in claim 5, containing a total of 100 μg or more of turmeronol A and turmeronol B per daily intake.

7. The composition of claim 1, administered to a human not having renal disease or impairment.

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