Mealy kudzu

Mealy Kudzu (Pueraria montana var. thomsonii): A Comprehensive Reference

1. Identity: Botanical Names, Source, and Common Forms

1.1 Nomenclature and Taxonomy

Mealy Kudzu is a widely used common name for Pueraria montana var. thomsonii (Benth.) M. R. Almeida, a member of the family Fabaceae (Leguminosae), subfamily Papilionoideae, tribe Phaseoleae. The substance is listed under a broad cluster of synonyms and common names, including Mealy Kudzu, Pueraria montana var. thomsonii, Pueraria thomsonii, Ge Gen, Gegen, Fengen, Fenge, Fen Ke, Japanese Arrowroot, East Asian Arrowroot, Kudzu Vine, Radix Puerariae, and Vigne Kudzu, among others. Kudzu root, known as Gegen in Chinese, is the dried root of Pueraria lobata (Willd.) Ohwi, a semi-woody, perennial and leguminous vine native to Southeast Asia; it is often used interchangeably in traditional Chinese medicine with Thomson kudzu root (Fengen in Chinese), the dried root of P. thomsonii, although the Chinese Pharmacopoeia has separated them into two monographs since the 2005 edition.

The genus Pueraria comprises 15–20 species of legumes native to south, east, and Southeast Asia and to New Guinea and northern Australia. Plants in the genus are lianas, shrubs, or climbing herbs, usually with large tuberous roots, and typical habitats include seasonally dry tropical and subtropical forest, rainforest, forest margins, and scrub vegetation, often on limestone outcrops and in rocky areas.

The former variety, Pueraria montana var. lobata, is well known as Gegen (Chinese name), and Pueraria montana var. thomsonii is known as Fengen in Traditional Chinese Medicine (TCM). Pueraria is one of the earliest medicinal herbs used in China and has been employed as a traditional Chinese medicine, food source, and fodder for thousands of years.

1.2 Botanical Description

Mealy kudzu is a fast-growing, hairy, perennial vine of the pea family with large tuberous roots and spikes of fragrant purplish pea flowers. It is a tuberous vine that establishes huge taproots, forming a crown at the soil level from which up to 30 vines may grow, with individual vines extending up to 100 feet in length and to 1–4 inches in diameter.

1.3 Pharmacopoeial Status and Forms

In the Pharmacopoeia of the People's Republic of China (PPRC), there are two primary varieties of Pueraria: Pueraria montana var. lobata (Willdenow.) Maesen & S. M. Almeida ex Sanjappa et Predeep and Pueraria montana var. thomsonii. Puerariae lobatae Radix is considered one of the 50 fundamental herbs in Traditional Chinese Medicine; it is odorless, has a slight bitter-sweet taste, and can appear as unprocessed chunks with profuse powder inside, or roasted chunks.

In the Japanese Pharmacopoeia, products of kudzu root containing more than 2% puerarin as dry matter from the roots of Pueraria lobata (Willd.) Ohwi are used as crude drugs. Kudzu is categorized as a food supplement by the European Commission Health and Food Safety Department.

Common commercial preparations include:

• Bulk herb, powder, extracts in capsules and tablets.
• Pueraria starch processed into various cakes, cold drinks, vermicelli, and highly nutritional therapeutic foods.
• Kudzu-derived medicines are reported to relieve fever, lessen stiffness and pain, and act as an antiphlogistic; kudzu flower tea is widely consumed in China, and recently kudzu flower extracts have been used as health foods in Japan, reported to be an effective treatment for hangovers and obesity.
• In China, puerarin is approved for intravenous injection as a vasodilator to treat coronary heart disease, myocardial infarction, and angina.

1.4 Differentiation from Related Species

P. thomsonii and P. lobata are economically important food and medicinal plants; P. thomsonii contains a higher starch content than P. lobata and is known as starch kudzu, while P. lobata contains abundant isoflavones, particularly puerarin, and is known as kudzu in the Chinese Pharmacopoeia. At present, most cultivated varieties of Pueraria are P. thomsonii, while P. lobata mostly consists of wild varieties. Taken together, comparative analyses demonstrate that P. lobata is better suited for use as a medicine, whereas P. thomsonii is better suited as an edible food.

2. Traditional and Historical Use

2.1 Traditional Chinese Medicine (TCM)

For more than 2,000 years, kudzu root has been used as a herbal medicine for the treatment of fever, acute dysentery, diarrhoea, diabetes and cardiovascular diseases; kudzu root (Gegen in Chinese) is the dried root of Pueraria lobata (Willd.) Ohwi, a semi-woody, perennial and leguminous vine native to Southeast Asia.

The tea of Radix Puerariae was first recorded in the Chinese materia medica Shen Nong Ben Cao Jing (Pharmacopeia of Shen Nong, ~200 BC), and used as an antipyretic, antidiarrhetic, diaphoretic, and antiemetic agent. Over the centuries it has been used to treat alcoholism, hangover, gastric distress, high blood pressure and other circulatory problems, colds, flu, diabetes, skin rashes, kidney disease, and diabetic retinopathy.

In TCM classification, the root is characterized by specific energetic properties: its indications and properties include being sweet, pungent, and cool; entering lung and stomach meridians; it acts to release the muscles, cure fever, discharge measles, promote production of fluid and relieve thirst, and ascend Yang to stop diarrhea; it is applicable for treating high fever of exterior syndromes, muscle pain of the upper back and neck, measles with incomplete eruption, thirst due to warm diseases, Yin deficiency converting into dryness, and diarrhea or dysentery due to heat.

The plant contains a number of bioactive substances, such as isoflavones, which have found versatile uses for treating alcoholism, heart and vascular problems, infections, and diabetes. Puerariae lobatae Radix is therefore considered one of the 50 fundamental herbs in Traditional Chinese Medicine.

2.2 Traditional Use in Japan and Korea

Kudzu (Pueraria montana var. lobata) is widely known in Japan, China, Korea, and other Asian countries, where it is an ingredient for traditional food and an herbal ingredient for traditional medicines, particularly in Japan and China. Kudzu-derived medicines are traditionally used to relieve fever, lessen stiffness and pain, and act as an antiphlogistic, and kudzu flower tea is widely consumed in China.

2.3 Traditional Preparations

Traditional preparations of mealy kudzu roots have included:

• Decoction (tea): Cutting the fresh or dried tuber into small pieces (about ½ inch in diameter) and decocting for about 30 minutes.
• Starch preparations: The starch powder made from East Asian arrowroot is called kudzu powder; kudzu powder is used to make arrowroot tea in traditional medicines of China, Japan and Korea.
• Raw or roasted root chunks: Puerariae lobatae Radix can appear as unprocessed chunks with profuse powder inside, or roasted chunks; the term refers to the root in fresh or dried, raw or processed (such as roasted) conditions.

3. Key Constituents and Active Compounds

3.1 Isoflavonoids

Over seventy phytochemicals have been identified in kudzu root, with isoflavonoids and triterpenoids as the major constituents. Evidence has shown that Pueraria isoflavone can play an active role in antioxidant, anti-inflammatory, anti-cancer, neuroprotection, and cardiovascular protection; over 50 isoflavones in kudzu root have been identified, including puerarin, daidzein, daidzin, 3′-hydroxy puerarin, and genistein, each with unambiguous structures.

Puerarin is the most important and best-characterized compound: The major isoflavone in kudzu is puerarin, which is the C8-glucoside of daidzein. The biological activity of Radix Puerariae has been attributed to its major isoflavonoid secondary metabolites, including daidzein and genistein, and their glycosides, especially daidzein 8-C-glucoside, also known as puerarin.

Kudzu roots are rich resources of natural product isoflavonoids, including daidzein, genistein, formononetin, and puerarin (also called daidzein 8-C-glycoside); among these isoflavonoids, puerarin is the major effective ingredient with antioxidative, antidiabetic, and antithrombotic effects, and it could also help to cure non-alcoholic fatty liver diseases, alcohol-induced adipogenesis, and osteonecrosis.

For the flower of P. thomsonii specifically, the kudzu flower extract from Pueraria thomsonii contains isoflavones such as tectoridin, tectorigenin 7-O-xylosylglucoside, tectorigenin, 6-hydroxygenistein-6,7-diglucoside, glycitin, glycitein, and genistein.

In terms of phytochemical markers distinguishing P. lobata from P. thomsonii: chemical analysis suggests isoflavonoids, including puerarin, daidzin, daidzein, and genistin, are the major constituents in P. thomsonii; however, 3-hydroxypuerarin and 3′-methoxypuerarin, which are normally found in P. lobata, were absent.

3.2 Starch, Fiber, and Other Constituents

P. thomsonii contains a higher starch content than P. lobata and is known as starch kudzu. It also contains various chemical compounds, such as isoflavonoids, triterpenoids, alkaloids, saponins, coumarins, and polysaccharides.

Dietary fiber is another essential component of the Pueraria genus; it is used to treat constipation, for detoxification, and to lower blood cholesterol and triglyceride levels.

3.3 Mechanisms of Action

Puerarin is rapidly absorbed from the intestine and exhibits beneficial effects for both cardiovascular and cerebrovascular health. Puerarin is metabolized to daidzein by intestinal bacteria.

Modern pharmacological studies have shown that puerarin has a variety of bioactive effects, including estrogen-like activity, anti-inflammation, antioxidant response, blood pressure control, blood glucose reduction, and cancer reduction.

The antioxidant and anti-inflammatory properties of puerarin provide the basis for its comprehensive biological effects; puerarin is perceived as a potential molecule that can be used in the prevention and/or treatment of various biodegenerative diseases.

Since the first isolation in the late 1950s, puerarin has been extensively studied for its effective and various pharmacological activities, including cardioprotection, vasodilation, anti-inflammation, antioxidant properties, attenuating insulin resistance, neuroprotection, alleviating pain, promoting bone formation, inhibiting alcohol intake, and anticancer effects.

Regarding estrogenic mechanisms, the root, due to its content of isoflavones, may possess phytoestrogenic properties. Isoflavones, the major components of kudzu, are thought to be responsible for its potential effects.

4. Scientific Evidence by Area of Use

4.1 Alcohol Use and Dependence

Apart from its long history of use as an anti-dipsotropic agent ameliorating the effects of alcohol abuse, there is growing evidence suggesting that puerarin may reveal health benefits in cardiovascular disease, osteoporosis, and neurodegenerative disorders.

Preclinical evidence: In animal studies, feeding with kudzu root suppressed alcohol intake and withdrawal symptoms.

Clinical evidence: Early research suggests that heavy drinkers who take kudzu extract for 7 days consume less beer when given a chance to drink. In a pilot study evaluating puerarin, ten physically and mentally healthy adult volunteers (average age of 25.8 years ± 3.2) who drank on average 17.6 ± 9.7 drinks per week completed the study; eight were men and two were women; none were diagnosed with current or past alcohol dependence according to DSM-IV criteria.

Puerarin particularly has been credited with influencing alcohol consumption patterns, although the mechanism by which this might occur is unknown.

Evidence strength: Studies of kudzu in humans are limited and have mostly focused on whether it can reduce alcohol intake or menopausal symptoms; however, all of these studies enrolled small numbers of patients, and systematic reviews have determined that the evidence of benefit for any condition is unclear.

4.2 Cardiovascular and Cerebrovascular Disease

Preclinical mechanisms: Puerarin has been extensively studied for cardioprotection, vasodilation, anti-inflammation, antioxidant, and attenuation of insulin resistance. Experimental and clinical investigations have reported that puerarin is widely used in the treatment of cardiovascular diseases, diabetes and its complications, Alzheimer's disease, Parkinson's disease, osteonecrosis, endometriosis, and cancer.

Clinical evidence: Early research suggests that injecting 500 mL of puerarin intravenously once daily for 3 weeks might reduce LDL cholesterol, increase HDL cholesterol, and reduce pre-meal insulin levels in people with coronary heart disease; however, puerarin injection products are not available in North America. The safety and efficacy of puerarin have been established in humans, especially in China where it is approved for intravenous injection as a vasodilator to treat coronary heart disease, myocardial infarction, and angina.

In countries outside China, only a few clinical trials have been conducted to investigate the effect of puerarin on cardiovascular diseases.

Evidence strength: Evidence for cardiovascular benefit from oral preparations is preliminary. The intravenous pharmaceutical use in China represents a more established clinical context, but this is distinct from the oral dietary supplement form. Beneficial outcomes on human health are still unclear due to limited availability of well-designed clinical trials; most of the publications are in Chinese literature, which at times restricts access to non-Chinese readers.

4.3 Menopausal Symptoms and Estrogenic Effects

Small clinical studies suggest that kudzu is a phytoestrogen that may help reduce menopausal symptoms, but a systematic review did not find benefit.

Clinical trials: In a clinical trial, fifty postmenopausal women were randomized equally into five different dose regimen groups of kudzu root extract in a four-week, parallel-group, open-label, single-center, exploratory study design; biomarkers CTX-I and CTX-II reflecting bone and cartilage degradation were assessed in blood samples and 24-hour urine samples; change from baseline in the Menopause Rating Scale (MRS) and subscales was also evaluated.

The results indicate that kudzu extract may possess beneficial effects on bone and cartilage health and may be a promising natural alternative to existing treatments for menopausal symptoms; kudzu root extract was well tolerated for short-term treatment of mild to severe menopausal symptoms in women in all tested doses and dose frequencies.

In one trial of 25 menopausal females, a decrease in the number of hot flushes per day occurred when a multiple-ingredient preparation containing kudzu extract was used.

A double-blind, placebo-controlled human trial examined the effects of Pueraria on blood lipids, bone alkaline phosphatase, and endometrial thickness and breast parameters in postmenopausal women aged 45–60 years; after 6 months, the groups receiving Pueraria showed a significant decrease in bone alkaline phosphatase, suggesting a reduction in bone resorption and turnover.

Evidence strength: Though kudzu root has been used for many years in traditional Chinese medicine, evidence regarding dose regimens, their pharmacological profile, effect on bone and cartilage turnover, and potential to treat menopausal symptoms of kudzu extracts is limited.

4.4 Diabetes and Blood Glucose Regulation

Clinical evidence: Early research suggests that taking puerarin 750 mg daily by mouth along with the diabetes medication rosiglitazone reduces blood sugar in patients with type 2 diabetes; however, injecting puerarin intravenously does not appear to reduce blood sugar.

Preclinical evidence: Antihyperglycemic effects of puerarin have been documented in streptozotocin-induced diabetic rat models. P. montana var. thomsonii is a notable medicinal plant known for its pharmacological activities, including heart and brain protection, hepatoprotection, and hypotensive and hypoglycemic properties.

Evidence strength: Evidence in humans is preliminary and limited. The available human data for oral supplementation in diabetes management consist of small, early-phase studies. Limited clinical studies exist to recommend use for any indication.

4.5 Bone and Cartilage Health

Naturally occurring isoflavones from Radix Pueraria lobata, kudzu root, may possess chondroprotective and symptom-relieving properties, but efficacy and safety of dosing and dose frequencies required for pharmacological action is unclear.

Isoflavones from Pueraria roots inhibited loss of bone density and lipid elevation; both animal and human studies have shown kudzu isoflavones to reduce lipid elevations and accumulation of abdominal fat that may follow rapid declines in estrogen levels.

Evidence strength: Preclinical data are supportive but clinical evidence remains sparse and derived from small exploratory trials only.

4.6 Lipid Regulation

Both animal and human studies have shown kudzu isoflavones to reduce lipid elevations and accumulation of abdominal fat that may follow rapid declines in estrogen levels; in a small clinical trial comparing Pueraria to placebo on serum lipids of postmenopausal women, after 2 months, high-density lipoprotein was 34% higher and low-density lipoprotein was 17% lower in the group receiving Pueraria.

Evidence strength: Evidence for lipid-lowering effects is preliminary and comes from small, short-duration studies. Further larger, controlled trials are needed.

4.7 In Vitro and Preliminary Findings

In vitro, kudzu has demonstrated antiproliferative, anti-inflammatory, and neuroprotective properties. Studies of kudzu in humans are limited and have mostly focused on its effects on alcohol consumption or climacteric symptoms. These in vitro findings do not establish clinical efficacy and should be regarded as hypothesis-generating only.

5. Body Systems and Health Areas

Based on the available scientific and traditional literature, mealy kudzu and its constituents are associated with the following body systems and health areas:

• Cardiovascular system: Vasodilatory, cardioprotective, and antithrombotic activity ascribed to puerarin; used clinically in China by intravenous route for coronary heart disease and angina.
• Endocrine/reproductive system: Phytoestrogenic activity of isoflavones relevant to menopausal symptom management and bone health in postmenopausal women.
• Metabolic system: Antihyperglycemic and hypolipidemic properties; investigated for type 2 diabetes and metabolic syndrome.
• Musculoskeletal system: The root acts as a general tonic that calms the nerves and heart and relaxes tension and spasms in the upper body. Potential chondroprotective and bone-protective effects.
• Central nervous system: Neuroprotective properties reported in vitro and in animal models; puerarin investigated for Alzheimer's and Parkinson's disease in preclinical settings.
• Gastrointestinal system: Traditional use for diarrhea, dysentery, and gastrointestinal distress.
• Immune/inflammatory system: Anti-inflammatory activity attributed to puerarin.
• Hepatic system: Antioxidant and hepatoprotective properties reported in preclinical studies.

6. Dosage Forms and Reported Dosages

Clinical trial data are lacking to support specific dosing recommendations. The following dosages have been reported in specific published studies:

• Oral capsules/tablets (menopausal/bone study): The lowest total daily dose regimen of three capsules was equivalent to 0.84 g of kudzu extract (corresponding to 113 mg puerarin) and the maximum daily dose of nine capsules corresponded to 2.52 g (corresponding to 338 mg of puerarin).
• Oral puerarin (diabetes study): Taking puerarin 750 mg daily by mouth along with the diabetes medication rosiglitazone was studied for blood sugar reduction in type 2 diabetes patients.
• Intravenous puerarin (cardiovascular study): Injecting 500 mL of puerarin intravenously once daily for 3 weeks was studied for lipid and insulin effects in people with coronary heart disease.
• Dried root powder (traditional dosing range): A starting dosage of five to 15 grams of dried powder per day has been reported in traditional practice.

7. Safety Considerations and Drug Interactions

7.1 General Tolerability

Kudzu root extract was well tolerated for short-term treatment of mild to severe menopausal symptoms in women in all tested doses and dose frequencies. Other small studies reported no significant adverse effects.

7.2 Documented Adverse Event Reports

Renal: A middle-aged woman consumed kudzu root juice to promote health and well-being for 10 days; she subsequently developed anorexia, epigastric discomfort, and azotemia; these symptoms improved rapidly within several days after discontinuation and conservative treatment; acute interstitial nephritis was diagnosed by renal biopsy. To the authors' knowledge, this is the first case report describing acute interstitial nephritis following the ingestion of kudzu root juice.

Hepatic: Liver injury has been reported in a 55-year-old man previously in good health who was hospitalized with mild fever, brown urine, and elevated AST/ALT levels. Two cases of symptomatic toxic hepatitis developed in middle-aged women after ingesting arrowroot juice; the clinical manifestations were nausea, vomiting, and jaundice; the diagnosis of toxic hepatitis was made using the Roussel Uclaf Causality Assessment Method score; after supportive care, the patients showed rapid improvements.

In one study of postmenopausal women: Transient negative profiles including anemia and liver profile changes were noted in one small study of postmenopausal women.

Animal toxicology: A mouse and rat toxicity study evaluated the acute and subchronic toxicity effects of 5 g/kg body weight of Pueraria flower extract and reported no mortality or toxicological changes during the experimental period.

7.3 Drug Interactions

Methotrexate (serious animal interaction): A rat study that administered 4.0 and 2.0 g/kg of Pueraria root decoction with methotrexate caused 57.1% mortality in the 4.0 g/kg group and 14.3% mortality in the 2.0 g/kg group. The concurrent use of intravenous methotrexate and kudzu root decoction at 4 g/kg enhanced the half-life of methotrexate by 53.9% and declined its clearance by 47.9%; this study suggested that the mechanism of diminished elimination might relate to the competition between methotrexate and metabolites on organic anion transporter in hepatobiliary and renal systems.

Cytochrome P450 inhibition: Puerarin may inhibit hepatic cytochrome P450-mediated drug metabolism in rats and humans, so interactions with some drugs are possible.

Antidiabetic medications: Animal studies suggest a key component in kudzu may increase the activity of antidiabetic medications; clinical relevance has yet to be determined.

Anticoagulants and blood-clotting: Kudzu might slow blood clotting and increase the risk of bleeding; taking it with other supplements with similar effects might increase the risk of bleeding in some people, including garlic, ginger, ginkgo, nattokinase, and Panax ginseng.

Cardiovascular drugs: There is a concern that kudzu might interfere with cardiovascular treatments; kudzu extracts seem to lower blood pressure and affect heart rhythm in animals.

7.4 Hormone-Sensitive Conditions

Because animal and human studies suggest some estrogenic effects, individuals with hormone-sensitive cancers and those taking tamoxifen should avoid kudzu. Current evidence suggests that Pueraria is safe for women with existing or a history of breast and uterine cancer; puerarin, the major isoflavone, has been shown to decrease the overexpression of estrogen receptors.

7.5 Pregnancy and Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

References

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• ScienceDirect: Kudzu root: Traditional uses and potential medicinal benefits in diabetes and cardiovascular diseases — Wong et al. (2011)
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