Herbs and Diabetes Mellitus
Bitter melon
What is it?
 Momordica charantia; also known as karela, bitter gourd, African cucumber, ku gua, karavellaka, and
balsam pear
 It grows in tropical areas, including parts of East Africa, Asia, the Caribbean, and South America,
where it is consumed as a vegetable
 Bitter melon is a green cucumber-shaped fruit with gourd-like bumps all over it
 You should consume fruit that is firm, yet bitter
 Bitter melon is confirmed to have antidiabetic, laxative, and antimicrobial properties (both fruit and
seeds)
Compounds that help control diabetes
 Charantin, extracted by alcohol, is a hypoglycemic (glucose-lowering) agent composed of mixed
steroids more potent than the drug tolbutamide, often used in the treatment of diabetes
 Saponin extracted from bitter melon fruit is demonstrated to inhibit both disaccharidase and pancreatic
lipase activity, preventing blood sugar and neutral fat elevation, respectively; is also is believed to
inhibit active transport of glucose across the intestinal border by inhibiting adenosine triphosphate
(ATP) production
 Cucurbitane triterpenoids extracted with methanol are demonstrated to have hypoglycemic effects in
mice
 The oral administration of 50–60 milliliters (mL) of the juice (amount from four to five fruits) has
shown positive hypoglycemic effects in clinical trials
 The water-extracted powder of fresh, unripe whole fruits at a dose of 20 milligrams (mg)/kilogram
(kg) body weight was found to reduce fasting blood glucose by 48% in one study
The facts
 In a randomized, double-blind, placebo-controlled trial of 40 patients with type 2 diabetes, either
poorly controlled or newly diagnosed, two capsules three times/day after meals for 3 months led to a
mild improvement in A1c levels in those taking the bitter melon, while there was no effect on blood
glucose levels, lipids, or weight:
– Participants also received standard therapy
– Baseline A1cs were between 7%–9%
– The authors note that the results are not strong enough to draw a conclusion regarding the
effectiveness of bitter melon for improving glycemia
 Animal studies have demonstrated numerous benefits of bitter melon extracts:
– Antioxidant properties, such as the inhibition of lipid oxidation and glutathione recycling
– Hepatoprotective effects by increasing antioxidant levels of liver enzyme activities
– Ability to stimulate insulin and repair damage in pancreatic beta cells
– Ability to stimulate production of insulin and adiponectin in adipose cells
– Significant lipid improvement
 Bitter melon may lower blood sugar by several specific actions:
– Enhances glucose uptake at suboptimal concentrations of insulin in certain fat cells
– Enhances insulin secretion by the islets of Langerhans
– Reduces glycogenesis in the liver
– Improves peripheral glucose utilization
– Increases serum protein levels
 Excessively high doses of bitter melon juice can cause abdominal pain and diarrhea
 Small children or anyone with hypoglycemia should not take bitter melon, because this herb could
theoretically trigger or worsen hypoglycemia
 People with diabetes taking oral hypoglycemic drugs, such as chlorpropamide, glyburide, or
metformin, or insulin should use bitter melon with caution, because it may increase the effectiveness
of the drugs, leading to severe hypoglycemia
Fenugreek
What is it?
 Trigonella foenum-graecum; also known as Greek hay or trigonella
 One of the oldest cultivated medicinal plants, ancient Egyptians used it to induce childbirth, while
early Greek and Roman herbalists used this ancient spice to treat diabetes
 It is an annual herb native to the Mediterranean region and Asia, often used as a cooking spice
 Commercial fenugreek comes primarily from Morocco, Turkey, India, and China; also grown widely
in Argentina, France, India, North Africa, and the United States
 The fenugreek plant reaches a height of 0.3–0.8 meters and has trifoliate leaves, with white flowers
appearing in early summer and developing into long, slender, yellow-brown pods containing the
brown seeds
Compounds to help control diabetes
 The defatted portion of the fenugreek seed contains the alkaloid trigonelline, nicotinic acid, and
coumarin, which many think are the ingredients responsible for its antidiabetic properties
 Fenugreek seeds contain approximately 50% mucilaginous fiber, which serves to slow down the rate at
which food is emptied from the stomach—this delays absorption of glucose by the small intestine,
resulting in lower blood sugar levels
The facts
 Most clinical studies on fenugreek are small, have inadequately reported results, or are poorly
controlled
 Typical doses include:
– 10–15 grams (g)/day seed powder, either in single or divided doses with meals
– 1 g hydroalcoholic extract
– 6 g/day cut or crushed seeds (in foods)
 Rats given seed extract for 6 weeks showed significantly reduced glucose, A1c, total cholesterol, and
triglyceride levels, with increased high-density lipoprotein (HDL); response was dose dependent
 Rats fed soluble fiber fractions of fenugreek seed significantly improved oral glucose tolerance by
decreasing intestinal disaccharidase activity and glucose absorption, as well as increasing
gastrointestinal motility
– Feeding of the fraction for 28 days led to decreased serum glucose, increased liver glycogen, and
increased total body antioxidant status, but had no effect on serum insulin or insulin secretion
– The authors concluded that “the present findings indicate that the SDF (soluble fiber) fraction of T
foenum-graecum seeds exerts antidiabetic effects mediated through inhibition of carbohydrate
digestion and absorption, and enhancement of peripheral insulin action”
 In vivo experiments have shown that fenugreek seed powder affects glycemia by influencing the
expression of liver pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), as well as
the GLUT4 glucose transporter in skeletal muscle
 Pregnant women should not consume fenugreek; the main side effect is gastrointestinal distress
 Patients taking glucose-lowering medications should use caution if taking fenugreek, because of the
risk of severe hypoglycemia
Bilberry
What is it?
 Vaccinium myrtillus; also known as whortleberry or European blueberry
 Bilberry is found in North America, Europe, and northern Asia
 It is a relative of blueberry, cranberry, and huckleberry:
– The fruit looks and tastes much like the American blueberry
– It also appears much like the blueberry, but it produces single or pairs of berries on the bush instead
of clusters
 Bilberry is a shrub that grows to about 16″ in height, with oval, pointed leaves and small pink and
white flowers, which bloom from April through June; in the late summer, its dark purple berries are
ripe to pick
 The fruit of the plant is eaten or made into extracts
 The leaves of the plant are made into extracts or teas
Compounds to help control diabetes
 Anthocyanins found in bilberries appear to possess significant antioxidant, chemopreventive,
anticarcinogenic, and antiparasitic effects, based on animal and in vitro studies
 Recent research has demonstrated that quercetin, a flavonoid found in bilberry, acts as an antioxidant
by activating a detoxification system that is genetically controlled, and more specifically, by regulating
the promoter region of the responsible genes
The facts
 Bilberries are eaten both fresh or in dried forms
 Fresh or dried berries, as well as the leaves of the bilberry plant, are used to make bilberry tea
 Bilberry extract—standardized to contain 25% anthocyanidins—contains the highest percentage of
anthocyanidins, making it the most potent form of bilberry
 No clinical data exists to support the use of bilberry as a dietary supplement for any reason
 No support is available for claims that bilberry has antidiabetic properties, despite its common use for
that purpose
Garlic
What is it?
 Allium sativum
 Garlic is probably descended from the Allium longicuspis species, which grows wild in southwestern
Asia
 It is closely related to the onion, shallot, and leek
 The portion of the plant most often consumed is an underground storage structure called a head, which
is composed of a dozen or more discrete cloves
Compounds to help control diabetes
 It is thought that the principal active ingredients are allyl propyl disulphide (APDS) and diallyl
disulphide oxide (allicin), although other constituents, such as flavonoids, may play a role as well
 Allicin has known antibiotic and antifungal properties
The facts
 Garlic actually creates the chemicals that give it its sharp flavor when the plant’s cells are damaged, as
when the clove is broken by chopping, chewing, or crushing
 Although initially promising, research has not turned out in support of using garlic as a supplement to
improve glycemia or lipids when viewed as thorough evidence analysis; its use as an antioxidant is
somewhat more hopeful
 Garlic is safe for most people
 Possible side effects include bad breath, stomach upset, heartburn, or allergic reactions, most common
from eating raw garlic
 In larger quantities, garlic may cause thinning of the blood
 Patients should use with caution prior to dental or surgical procedures, or if they have bleeding
disorders or are taking blood thinners
Asian/American ginseng
What is it?
 Asian ginseng is commonly used in traditional Chinese medicine to treat diabetes
 Asian ginseng is native to China and Korea, where it has had medicinal use for centuries
 Both American and Asian ginseng belong to a genus of 11 species of slow-growing perennial plants
with fleshy roots, in the family Araliaceae; both are “true” ginsengs
 It appears as a light-tan, gnarled root, with stringy shoots that look like arms and legs
 The dried root is used to make tablets, capsules, teas, creams, and extracts
Compounds to help control diabetes
 The active chemical components are called ginsenosides (or panaxosides)
 Ginsenosides are shown to enhance the release of insulin from the pancreas and to increase the number
of insulin receptors, as well as to have a direct blood sugar-lowering effect
The facts
 Used traditionally and currently:
– For general wellness
– For stamina
– To speed recovery from illness
– To improve mental and physical performance
– For lowering blood pressure and glucose levels
– To improve symptoms of menopause
– To treat erectile dysfunction and hepatitis C
 A recent study found that 200 mg of ginseng extract/day improved blood sugar control, as well as
energy levels in people with type 2 diabetes
 Recent rat studies have demonstrated significant effects of ginseng, including:
– Decreases in blood glucose, A1c, advanced glycation end products (AGEs), and cholesterol
– Antioxidant activity, including cytoprotective effects and protection against lipid peroxidation
– Direct modification of diabetic genes
– Improved creatinine clearance
– Decreased body weight
 Overall the clinical data regarding the antidiabetic effect of ginseng looks positive, but is still
preliminary; the National Center for Complementary and Alternative Medicine is funding further
research in this area
 Side effects include:
– Headache
– Sleep disturbance
– Gastrointestinal symptoms
 Patients taking medications to lower their blood sugar or using other alternative remedies that may
lower their blood sugar should use caution when taking Asian/American ginseng, because of its
potential to lower blood sugar levels
 Ginseng is a potential allergen
Dandelion
What is it?
 Taraxacum officinale; also called lion’s tooth or blowball
 Dandelion grows in the temperate regions of Europe, Asia, and North America
 It is a hardy, variable perennial that can grow to a height of nearly 12″
 Its deeply notched, toothy, spatula-like leaves are shiny and hairless
 Dandelion stems are capped by a head of bright yellow flowers
Compounds that help control diabetes
 Contains a compound called inulin, which traps glucose molecules and prevents them from reaching
high concentrations in the bloodstream; inulin is becoming well known for its use as a functional fiber
 Inulin also appears to act directly on the pancreas to increase insulin production
The facts
 Studies have shown that dandelion extracts can reduce blood sugar levels by as much as 20% in as
little as 2 hours
 Dandelion leaves are a rich source of vitamins A, B complex, C, and D, as well as minerals, such as
iron, potassium, and zinc; great used in salads
 Traditionally, dandelion was used to treat problems of the kidney, liver, spleen, and intestine
 In modern times, dandelion is sometimes used as a “tonic” for the kidney or liver, for mild digestive
problems, or as a diuretic
References and recommended readings
Ahmad MS, Ahmed N. Antiglycation properties of aged garlic extract: possible role in prevention of
diabetic complications. J Nutr. 2006;136(suppl 3):796S-799S.
Cicero AF, Derosa G, Gaddi A. What do herbalists suggest to diabetic patients in order to improve
glycemic control? Evaluation of scientific evidence and potential risks. Acta Diabetol. 2004;41:91-98.
Dans AM, Villarruz MV, Jimeno CA, et al. The effect of Momordica charantia capsule preparation on
glycemic control in type 2 diabetes mellitus needs further studies. J Clin Epidemiol. 2007;60:554-559.
National Center for Complementary and Alternative Medicine. Herbs at a glance: fenugreek. Available
at: http://nccam.nih.gov/health/fenugreek/. Accessed June 12, 2012.
National Center for Complementary and Alternative Medicine. Herbs at a glance: garlic. Available at:
http://nccam.nih.gov/health/garlic/. Accessed June 12, 2012.
National Center for Complementary and Alternative Medicine. Herbs at a glance: ginseng. Available at:
http://nccam.nih.gov/health/asianginseng/. Accessed June 12, 2012.
National Institutes of Health, National Institutes of Health. Dietary supplements fact sheets. Available
at: http://ods.od.nih.gov/factsheets/list-all/. Accessed June 12, 2012.
Raju J, Gupta D, Rao AR, Yadava PK, Baquer NZ. Trigonellafoenum graecum (fenugreek) seed powder
improves glucose homeostasis in alloxan diabetic rat tissues by reversing the altered glycolytic,
gluconeogenic and lipogenic enzymes. Mol Cell Biochem. 2001;224:45-51.
Raza H, Ahmed I, Lakhani MS, Sharma AK, Pallot D, Montague W. Effect of bitter melon (Momordica
charantia) fruit juice on the hepatic cytochrome P450-dependent monooxygenases and glutathione Stransferases in streptozotocin-induced diabetic rats. Biochem Pharmacol. 1996;22:1639-1642.
Tapsell LC, Hemphill I, Cobiac L, et al. Health benefits of herbs and spices: the past, the present, the
future. Med J Aust. 2006;185(suppl 4):S4-S24.
Virdi J, Sivakami S, Shahani S, Suthar AC, Banavalikar MM, Biyani MK. Antihyperglycemic effects of
three extracts from Momordica charantia. J Ethnopharmacol. 2003;88:107-111.
Review Date 6/12
D-0516