Chromium

Overview

It is estimated that 90% of American diets are deficient in chromium, and the general population is thought to show signs of a marginal deficiencies, such as impaired glucose tolerance. Typical food sources of chromium include brewer’s yeast, whole grain cereals, broccoli, prunes, mushrooms and beer. However, the typical American diet is thought to exacerbate the problem of deficiency by the large-scale consumption of simple sugars in processed foods that may block chromium absorption. Brewer’s yeast, also called nutritional yeast, is thought to be the most bioavailable form of chromium, as it part of a bioactive complex called glucose tolerance factor (GTF) (Sterns et al., 1995).

Chromium is one of the essential trace minerals, and is important for carbohydrate metabolism and the potentiation of insulin. As chromium is well known for its difficulty in absorption, with only about 3% of the chromium we intake being absorbed, supplementation is a viable option. However, there are many types of chromium supplements on the market, and there have been recent concerns over the potential for toxicity of chromium picolinate, one of the most studied supplemental forms of chromium. These concerns have not been validated. Chromium chloride as well as some other forms of chromium (III) supplements do not have this concern (Vincent, 2000; Vincent 2003).

Comments

Although evidence is still mounting for the use of chromium to normalize blood sugar and meet marginal deficiencies, there seems to be a great potential as a supplement as the American population is sorely in need of nutritional answers to its large and growing overweight and diabetic populations.

Scientific Support

Athletic Performance

Chromium’s clinical results so far for enhancing exercise performance have been limited. In a double-blind clinical study on the effects of chromium picolinate supplementation on football players, 200 mcg daily was administered. The outcome measurements were urinary excretion, girth and skinfold measures, percent body fat, lean body mass, and isometric and dynamic strength. No changes in any of the parameters were found, except for an increase in urinary chromium output (Clancy et al., 1994).

In two earlier studies, 200 mcg daily of chromium supplementation failed to show results. One study involved college students during weight training, and the only group that showed a significant difference were the females, who had a significant increase in body weight (Hasten et al., 1992). In another double-blind placebo controlled study, no enhancement on athletic performance was found (Walker et al., 2000).

Weight Loss

Mixed results have been found clinically for chromium picolinate in weight loss. Pittler et al. (2003) performed a meta-analysis of chromium as it had been administered in randomized, double-blind, placebo controlled studies that reported on chromium picolinate’s use in weight loss. Ten studies matched the criteria of the meta-analysis, and the authors found a small benefit for the use of chromium picolinate in weight loss.

Volpe et al. (2001) tested the effects of chromium picolinate supplementation on body composition, resting metabolic rate, and zinc status in moderately obese women who underwent a prescribed exercise program. No changes in any of the measured outcomes were found except for a reduction in serum total cholesterol levels and total iron building capacity in both groups due to the increase in exercise for both groups.

In a clinical study on the effects of chromium picolinate supplementation on the risk factors for coronary artery disease and type II diabetes in obese women, 400 mcg daily was administered. In the groups that underwent exercise, chromium supplementation resulted in significant weight loss, whereas, the groups that did not undergo exercise but used chromium has significant weight gain. Chromium supplementation was only recommended then by the authors for obese women who were undergoing an exercise program (Grant et al., 1997).

In an earlier double-blind, placebo controlled study, chromium picolinate (400 mcg daily) supplementation was administered and investigated for its effect on body composition in obese people undergoing and exercise program. The results of this study showed no difference between the placebo and chromium groups (Trent et al., 1995).

Blood Sugar Control/ Diabetes & Chromium Ions

Ryan et al. (2003) performed a review of chromium (III) supplements for diabetes type II and hyperlipidemia. It was found that chromium reduced blood glucose in hyperglycemia, but not in people with normal blood glucose levels. Chromium was found to have variable effects on lipid levels.

In another recent study, Keszthelyi et al. (2003) found chromium supplementation used in diabetics for 6 months resulted in significant reductions in cholesterin levels, as well as a slight reduction in the HbA1c level.

Anderson et al. (2001) studied the effect of combined and individual zinc and chromium supplementation on oxidative stress and glucose homeostasis in people with type II diabetes. Diabetic subjects were supplemented with 30 mg/day of zinc (as zinc gluconate), or 400 micrograms/day of chromium (as chromium picolinate), or the combination, or placebo. The authors concluded that there are potential beneficial antioxidant effects of taking either the individual or combined supplementation of zinc or chromium in type II diabetics.

Bahijri (2000) found an improved lipid profile and glycemic control in a study on healthy adults given chromium tetrachloride daily. In this double-blind study, 200 micrograms or placebo was given daily for 8 weeks.

In a general study of urine and serum concentrations in diabetic and normal subjects, Ding et al. (1998) found that chromium loss is associated with aging and also diabetes occurrence.

Chromium supplementation on diabetic patients (with type I and type II diabetes) was investigated. Chromium supplementation (200 mcg daily) produced beneficial results in reducing insulin sulfonylurea or metformin requirements. Greater results were found for type II diabetics, but type I diabetics also showed good results with supplementation (Ravina and Slezack, 1993).

Safety / Dosage

The RDI for chromium is 120 mcg. There have been many concerns about the toxicity of chromium picolinate, however several recent studies have confirmed its safety (Campbell et al, 2004; Rhodes et al., 2005).

References

1.Anderson RA, Roussel AM, Zouari N, Mahjoub S, Matheau JM, Kerkeni A. Potential antioxidant effects of zinc and chromium supplementation in people with type 2 diabetes mellitus. J Am Coll Nutr. 2001 Jun;20(3):212-8.

2.Bahijri SM. Effect of chromium supplementation on glucose tolerance and lipid profile. Saudi Med J. 2000 Jan;21(1):45-50.

3.Campbell WW, Joseph LJ, Ostlund RE Jr, Anderson RA, Farrell PA, Evans WJ. Resistive training and chromium picolinate: effects on inositols and liver and kidney functions in older adults. Int J Sport Nutr Exerc Metab. 2004 Aug;14(4):430-42.

4.Clancy SP, Clarkson PM, DeCheke ME, Nosaka K, Freedson PS, Cunningham JJ, Valentine B. Effects of chromium picolinate supplementation on body composition, strength, and urinary chromium loss in football players. Int J Sport Nutr. 1994 Jun;4(2):142-53.

5.Ding W, Chai Z, Duan P, Feng W, Qian Q. Serum and urine chromium concentrations in elderly diabetics. Biol Trace Elem Res. 1998 Sep;63(3):231-7.

6.Grant KE, Chandler RM, Castle AL, Ivy JL. Chromium and exercise training: effect on obese women. Med Sci Sports Exerc. 1997 Aug;29(8):992-8.

7.Hasten DL, Rome EP, Franks BD, Hegsted M. Effects of chromium picolinate on beginning weight training students. Int J Sport Nutr. 1992 Dec;2(4):343-50.

8.Keszthelyi Z, Past T, Koltai K, Szabo L, Mozsik G. Chromium (III)-ion enhances the utilization of glucose in type-2 diabetes mellitus. Orv Hetil. 2003 Oct 19;144(42):2073-6.

9.Pittler MH, Stevinson C, Ernst E. Chromium picolinate for reducing body weight: meta-analysis of randomized trials. Int J Obes Relat Metab Disord. 2003 Apr;27(4):522-9.

10.Ravina A, Slezack L. Chromium in the treatment of clinical diabetes mellitus. Harefuah. 1993 Sep;125(5-6):142-5, 191.

11.Rhodes MC, Hebert CD, Herbert RA, Morinello EJ, Roycroft JH, Travlos GS, Abdo KM. Absence of toxic effects in F344/N rats and B6C3F1 mice following subchronic administration of chromium picolinate monohydrate. Food Chem Toxicol. 2005 Jan;43(1):21-9.

12.Ryan GJ, Wanko NS, Redman AR, Cook CB. Chromium as adjunctive treatment for type 2 diabetes. Ann Pharmacother. 2003 Jun;37(6):876-85.

13.Stearns DM, Belbruno JJ, Wetterhahn KE. A prediction of chromium(III) accumulation in humans from chromium dietary supplements. FASEB J. 1995 Dec;9(15):1650-7.

14.Trent LK, Thieding-Cancel D. Effects of chromium picolinate on body composition. J Sports Med Phys Fitness. 1995 Dec;35(4):273-80.

15.Walker LS, Bemben MG, Bemben DA, Knehans AW.Chromium picolinate effects on body composition and muscular performance in wrestlers. Med Sci Sports Exerc. 1998 Dec;30(12):1730-7.

16.Volpe SL, Huang HW, Larpadisorn K, Lesser II. Effect of chromium supplementation and exercise on body composition, resting metabolic rate and selected biochemical parameters in moderately obese women following an exercise program. J Am Coll Nutr. 2001 Aug;20(4):293-306.

EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.

Fenugreek

Overview

Fenugreek is a popular spice in Indian cuisine and has a long use in both Ayervedic and Chinese traditional medicine, for uses including inducing lactation, inducing labor, aiding in digestion, and as a general health and wellness tonic (Basch et al., 2003; Gabay, 2002). Both animal and human clinical studies are finding that fenugreek shows promising therapeutic activity as a hypoglycemic and hypocholesterolaemic agent. The unique dietary fibers along with the high saponin content, and possibly an amino acid (4-Hydroxyisoleucine) in fenugreek is thought to be responsible for its activities (Madar, 2002; Sauvaire et al., 1998).

Comments

Vajifdar et al. (2000) included fenugreek dietary fiber in a dietary fiber mixture in a study which had favorable results on lowering LDL cholesterol, apolipoproteine A-1, body mass index and waist circumference. As the mechanisms of action of dietary fiber are assumed to be similar, this study shows promise for the use of fenugreek fiber for being helpful in ischemic heart disease. Likewise, fenugreek was found beneficial in the diabetic diet when combined with millet and legumes in another clinical study, and a combination of other herbs (Pathak et al., 2000; Bhardqaj et al., 1994).

Scientific Support

Type I & II Diabetes

Madar et al. (2002) tested the dietary effect of fenugreek in type II diabetics (non-insulin dependent) following the meal tolerance test (MTT). Powdered fenugreek (15 g) was added to the diets of type II diabetics, and found to significantly reduce the postprandial glucose levels, and non-significantly lower the plasma insulin levels as well. There was no effect on the blood lipid levels after 3 hours following the MTT.

Gupta et al. (2001) performed a double-blind, randomized, placebo-controlled study to determine the effect of fenugreek on glycemic control and insulin resistance in type II diabetics. The participants were given either fenugreek extract (hydroalcoholic; 1 g daily) or placebo for two months. Serum triglycerides were found to be reduced in the treatment group, as well as insulin control a a decrease in insulin resistance.

Sharma et al. (1990) tested the effect of fenugreek seeds on type I diabetic’s blood glucose levels and serum lipid profiles in a placebo-controlled clinical study. Fenugreek seed was administered in the treatment group diet (100 g daily), whereas isocaloric diets without fenugreek served as the control, and the diets were followed for 10 days. A 54% reduction in 24-hour urinary glucose excretion, along with significantly reduced serum total cholesterol, LDL, and VLDL cholesterol and triglycerides was found in the treatment group. The HDL levels remained unchanged between groups. The authors noted that fenugreek appeared useful in the diets of diabetics.

Hypocholesterolemic Effect

Sowmya and Rajyalakshmi (1999) tested the effect of dietary germinated fenugreek seed powder on blood lipid levels in hypocholesterolemic adults. Twenty participants were divided into two groups and asked to add the fenugreek powder to their meals for one month, the groups differed in the amount of fenugreek in the packet: either 12.5 g or 18 g daily. Both treatment levels resulted in a hypocholesterolemic effect, but the 18 g dosage resulted in significant reductions in total and LDL cholesterol levels. There were no changes found between the groups in HDL, VLDL and triglyceride levels. The authors claimed that the germination of the seeds was able to increase the solubility of the fiber content of fenugreek.

Safety / Dosage

Fenugreek seed powder has been found to be beneficial in the typical dosages of between 15-20 (and up) grams daily for reducing serum cholesterol levels and improving blood sugar control in diabetics. Fenugreek is considered quite safe, even at the higher doses needed for therapeutic use (Muralidhara et al., 1999). As is the case with other botanicals with high coumarin contents, there is concern with the potential adverse reaction of increasing bleeding, and an interaction with other blood-thinning drugs (Abebe, 2002).

References

1.Abebe W. Herbal medication: potential for adverse interactions with analgesic drugs. J Clin Pharm Ther. 2002 Dec;27(6):391-401.

2.Basch E, Ulbricht C, Kuo G, Szapary P, Smith M. Therapeutic applications of fenugreek. Altern Med Rev. 2003 Feb;8(1):20-7.

3.Bhardwaj PK, Dasgupta DJ, Prashar BS, Kaushal SS. Control of hyperglycaemia and hyperlipidaemia by plant product. J Assoc Physicians India. 1994 Jan;42(1):33-5.

4.Gabay MP. Galactogogues: medications that induce lactation. J Hum Lact. 2002 Aug;18(3):274-9.

5.Gupta A, Gupta R, Lal B. Effect of Trigonella foenum-graecum (fenugreek) seeds on glycaemic control and insulin resistance in type 2 diabetes mellitus: a double blind placebo controlled study. J Assoc Physicians India. 2001 Nov;49:1057-61.

6.Hibasami H, Moteki H, Ishikawa K, Katsuzaki H, Imai K, Yoshioka K, Ishii Y, Komiya T. Protodioscin isolated from fenugreek (Trigonella foenumgraecum L.) induces cell death and morphological change indicative of apoptosis in leukemic cell line H-60, but not in gastric cancer cell line KATO III. Int J Mol Med. 2003 Jan;11(1):23-6.

7.Madar Z, Abel R, Samish S, Arad J. Glucose-lowering effect of fenugreek in non-insulin dependent diabetics. Eur J Clin Nutr. 1988 Jan;42(1):51-4.

8.Madar Z, Stark AH.New legume sources as therapeutic agents. Br J Nutr. 2002 Dec;88 Suppl 3:S287-92.

9.Muralidhara, Narasimhamurthy K, Viswanatha S, Ramesh BS. Acute and subchronic toxicity assessment of debitterized fenugreek powder in the mouse and rat. Food Chem Toxicol. 1999 Aug;37(8):831-8.

10.Pathak P, Srivastava S, Grover S. Development of food products based on millets, legumes and fenugreek seeds and their suitability in the diabetic diet. Int J Food Sci Nutr. 2000 Sep;51(5):409-14.

11.Sauvaire Y, Petit P, Broca C, Manteghetti M, Baissac Y, Fernandez-Alvarez J, Gross R, Roye M, Leconte A, Gomis R, Ribes G. 4-Hydroxyisoleucine: a novel amino acid potentiator of insulin secretion. Diabetes. 1998 Feb;47(2):206-10.

12.Sharma RD, Raghuram TC, Rao NS. Effect of fenugreek seeds on blood glucose and serum lipids in type I diabetes. Eur J Clin Nutr. 1990 Apr;44(4):301-6.

13.Sowmya P, Rajyalakshmi P. Hypocholesterolemic effect of germinated fenugreek seeds in human subjects. Plant Foods Hum Nutr. 1999;53(4):359-65.

14.Vajifdar BU, Goyal VS, Lokhandwala YY, Mhamunkar SR, Mahadik SP, Gawad AK, Halankar SA, Kulkarni HL. Is dietary fiber beneficial in chronic ischemic heart disease? J Assoc Physicians India. 2000 Sep;48(9):871-6.

EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS

Gymnema

Overview

Gymnema sylvestre is a plant used medicinally in India and Southeast Asia for treatment of “sweet urine” or what we refer to in the West as diabetes or hyperglycemia. In ancient Indian (Ayurvedic medicine) texts, gymnema is referred to as gurmar, which means “sugar destroyer” in Sanskrit. Gymnema leaves, whether extracted or infused into a tea, suppress glucose absorption and reduce the sensation of sweetness in foods – effects which may deliver important health benefits for individuals who want to reduce blood sugar levels or body weight. Modern-day dietary supplements containing gymnema are typically intended for control of blood sugar and insulin levels, reduction of sugar cravings, and weight loss – particularly in patients with diabetes.

Comments

As a dietary supplement to enhance control of blood glucose and insulin, gymnema sylvestre appears to be effective – particularly in the case of individuals with diabetes or hyperglycemia (elevated blood sugar). As an agent to promote weight loss, gymnema may help control appetite and carbohydrate cravings – effects which may be helpful in some individuals attempting weight loss.

Scientific Support

Gymnema sylvestre leaves contain gymnemic acids, which are known to suppress transport of glucose from the intestine into the blood stream and a small protein, gurmar, that can interact with receptors on the tongue to decrease the sensation of sweetness in many foods (Miyasaka and Imoto 1995). This dual action has been shown to reduce blood sugar and cholesterol levels in diabetic animals and humans and may provide some benefits in terms of regulating appetite control and food cravings (Suttisri et al. 1995).

The hypoglycemic effect of gymnema has been known for centuries. Modern scientific methods have isolated at least nine different fractions of gymnemic acids which possess hypoglycemic activity (Chattopadhyay 1998, Fushiki et al. 1992). The effect of gymnema extract on lowering blood levels of glucose, cholesterol and triglycerides is fairly gradual – typically taking a few days to several weeks. Very high doses of the dried gymnema leaves may even help to repair the cellular damage that causes diabetes by helping to regenerate the insulin producing beta-cells in the pancreas (Shanmugasundaram et al. 1990).

Several human studies conducted on gymnema for treatment of diabetes have shown significant reduction in blood glucose, glycosylated hemoglobin (an index of blood sugar control) and insulin requirements (Baskaran et al. 1990, Khare et al. 1983). Gymnema appears to increase the effectiveness of insulin rather than causing the body to produce more (Shanmugasundaram et al. 1981) – although the precise mechanism by which this occurs remains unknown. As with other natural ingredients for control of blood sugar and insulin levels, such as banaba leaf, a common “side effect” is weight loss (Khare et al. 1983) – probably due to a combination of appetite suppression and control of food cravings (especially for carbohydrates and sweets).

Safety/Dosage

At typical recommended doses (see below), dietary supplements containing gymnema are not associated with significant adverse side effects. Mild gastrointestinal upset may occur if gymnema is taken on an empty stomach – so consumption with meals is recommended. Caution is urged, however, because of the potential to induce hypoglycemia in susceptible individuals. In those individuals with active diabetes, it is recommended to consult your personal physician before and during use of gymnema, as alterations to your dosage of insulin or other anti-diabetic medications may be warranted. Certain medications, including antidepressants (St. John’s wort) and salicylates (white willow and aspirin) can enhance the blood sugar-lowering effects of gymnema, whereas certain stimulants such as ephedra (Ma Huang) may reduce its effectiveness. Most human studies have been conducted in diabetic patients and have used 400-600mg of gymnema extract per day in conjunction with conventional oral anti-diabetic medications to lower blood glucose and reduce insulin requirements. In non-diabetics, smaller doses may be effective in helping to control blood sugar and insulin fluctuations – and the associated swings in appetite and food cravings. Because it acts gradually, gymnema extract should be consumed regularly with meals for several days/weeks.

References

1.Baskaran K, Kizar Ahamath B, Radha Shanmugasundaram K, Shanmugasundaram ER. Antidiabetic effect of a leaf extract from Gymnema sylvestre in non-insulin-dependent diabetes mellitus patients. J Ethnopharmacol. 1990 Oct;30(3):295-300.

2.Chattopadhyay RR. Possible mechanism of antihyperglycemic effect of Gymnema sylvestre leaf extract. Gen Pharmacol. 1998 Sep;31(3):495-6.

3.Fushiki T, Kojima A, Imoto T, Inoue K, Sugimoto E. An extract of Gymnema sylvestre leaves and purified gymnemic acid inhibits glucose-stimulated gastric inhibitory peptide secretion in rats. J Nutr. 1992 Dec;122(12):2367-73.

4.Khare AK, Tondon RN, Tewari JP. Hypoglycaemic activity of an indigenous drug (Gymnema sylvestre, 'Gurmar') in normal and diabetic persons. Indian J Physiol Pharmacol. 1983 Jul-Sep;27(3):257-8.

5.Miyasaka A, Imoto T. Electrophysiological characterization of the inhibitory effect of a novel peptide gurmarin on the sweet taste response in rats. Brain Res. 1995 Apr 3;676(1):63-8.

6.Murakami N, Murakami T, Kadoya M, Matsuda H, Yamahara J, Yoshikawa M. New hypoglycemic constituents in "gymnemic acid" from Gymnema sylvestre. Chem Pharm Bull (Tokyo). 1996 Feb;44(2):469-71.

7.Ota M, Shimizu Y, Tonosaki K, Ariyoshi Y. Role of hydrophobic amino acids in gurmarin, a sweetness-suppressing polypeptide. Biopolymers. 1998 Mar;45(3):231-8.

8.Shanmugasundaram ER, Gopinath KL, Radha Shanmugasundaram K, Rajendran VM. Possible regeneration of the islets of Langerhans in streptozotocin-diabetic rats given Gymnema sylvestre leaf extracts. J Ethnopharmacol. 1990 Oct;30(3):265-79.

9.Shanmugasundaram ER, Rajeswari G, Baskaran K, Rajesh Kumar BR, Radha Shanmugasundaram K, Kizar Ahmath B. Use of Gymnema sylvestre leaf extract in the control of blood glucose in insulin-dependent diabetes mellitus. J Ethnopharmacol. 1990 Oct;30(3):281-94.

10.Shanmugasundaram KR, Panneerselvam C, Samudram P, Shanmugasundaram ER. The insulinotropic activity of Gymnema sylvestre, R. Br. An Indian medical herb used in controlling diabetes mellitus. Pharmacol Res Commun. 1981 May;13(5):475-86.

11.Shimizu K, Abe T, Nakajyo S, Urakawa N, Atsuchi M, Yamashita C. Inhibitory effects of glucose utilization by gymnema acids in the guinea-pig ileal longitudinal muscle. J Smooth Muscle Res. 1996 Oct;32(5):219-28.

12.Shimizu K, Iino A, Nakajima J, Tanaka K, Nakajyo S, Urakawa N, Atsuchi M, Wada T, Yamashita C. Suppression of glucose absorption by some fractions extracted from Gymnema sylvestre leaves. J Vet Med Sci. 1997 Apr;59(4):245-51.

13.Shimizu K, Ozeki M, Tanaka K, Itoh K, Nakajyo S, Urakawa N, Atsuchi M. Suppression of glucose absorption by extracts from the leaves of Gymnema inodorum. J Vet Med Sci. 1997 Sep;59(9):753-7.

14.Suttisri R, Lee IS, Kinghorn AD. Plant-derived triterpenoid sweetness inhibitors. J Ethnopharmacol. 1995 Jun 23;47(1):9-26.

EDITOR'S NOTE: This monograph can be found in The Health Professional's Guide to Dietary Supplements (Lippincott, Williams & Wilkins) by Shawn M. Talbott, PhD and Kerry Hughes, MS.