Table 2.

Common dietary supplements used in the management of diabetes

S/no	Dietary supplement	Nutrients/ food source	Form found	Target organ/cell	Health benefits	Limitations	Reference
1.	Alpha-lipoic acid	Liver, spinach, broccoli and potato.	lipoic acid in tablet and capsule.	Nerve cell, kidney and liver.	Prevents cell damage, improves the body's ability to use insulin.	May lower blood sugar too much.	Jacob et al., 1995; 1996; Konrad et al., 1999.
2.	Chromium	Trace element, meat, whole grain products, some fruits, vegetables and spices.	Capsule and tablets sold as chromium picolinate, chromium chloride, chromium nicotinate.	Pancreas	Keeps pancreas working well and lowers blood sugar levels.	Lower doses are safer as high doses can cause kidney problem.	McCarty, 1999; Althuis et al., 2002; Cefalu and He, 2004; Balk et al., 2007; Jellin and Gregory, 2007.
3.	Omega-3fatty acids	Poly unsaturated fatty acids. Oil, vegetable oil (canola and soybean), walnuts, and wheat germ.	Capsule or oil.	Liver and heart.	Maintains blood glucose levels.	Safer at low to moderate doses, may interfere with certain medications.	Hartweg et al., 2007; Hartweg et al., 2008.
4.	Polyphenols	Tea and dark chocolate.	Green tea	Vascular tissue	Lowers blood glucose levels by enhancing insulin action.	Contains caffeine, which can cause, in some people, insomnia, anxiety, or irritability. Green tea also has small amounts of vitamin K, which can make anticoagulant drugs, such as warfarin, less effective.	Fukino et al., 2005; Ryu et al., 2006 Collins et al., 2007; Kim et al., 2007; Mackenzie et al., 2007; Potenza et al., 2007.
5.	Garlic	Allium sativum	S-ally cysteine sulphoxide (SACS).	Pancreas	Reduces fasting blood glucose and lower serum cholesterol levels.	Inhibits platelet Aggregation and may prolong bleeding time.	Sheela and Augusti, 1992; Kaczmar, 1998. Banerjee and Maulik, 2002.
6.	Magnissium	Fat or fibre from fruits, vegetables, cereals and grain.	Citrate, chloride, sulphate and stearate.	Heart, kidney and muscle.	Improves insulin response and glucose handling in the elderly and in type 2 diabetics.	Causes loose stool in sensitive individuals.	Begon et al., 2000; Larsson and Wolk, 2007; Schulze et al., 2007.
7.	Coenzyme Q10	B vitamins i.e. niacin and folic acid. Fatty fish, organ meat, peanuts, spinach.	Oil	Heart, liver and lungs.	Improves long-term glycemic control in type 2 diabetics.	Body stores of Co-Q10 can be reduced when used alongside prescribed diabetic medications such as glyburide.	Andersonet al, 2001; Hodgson et al., 2002; Bonadkdar and Guarneri, 2005.
8.	Vanadium	Black pepper, mushroom , shell fish parsley, fresh fruits and vegetables.	Chelate and sulphates.	Muscles, liver and body fluids.	Helps cells of both the liver and muscles use insulin more effectively, controls glucose and insulin sensitizers.	Adverse reactions of diarrhea, green Tongue, nausea, vomiting and cramps are reported.	Cusi et al., 2001.
9.	Folic Acid	Vitamin B9, spinach broccoli, avocado, oranges, tomatoes, banana.	Oxidized synthetic folate tablet form.	Liver and kidney	Along with B12, folic acid prevents strokes and loss of limbs due to diabetic complications.	High dosages cause neural damage.	Salardi et al., 2000.
10.	Selenium	Broccoli, raddish, cabbage, onion, garlic, cereals, meat, mushroom, fish , nuts and egg.	Chelate	Small intestine, kidney	Helps take blood sugar into cells, protects against blood vessel and nerve damage from elevated blood sugars.	Low blood selenium predisposes to cancer, coronary heart disease and diabetes.	Mukherjee et al., 1998; Stapleton, 2000.
11.	Vitamin B6	All bran, brown rice, oats, molasses, wheat germ, banana, plum, fish and salmon.	Pyridoxine	Jejunum, ileum	Pyridoxine with folic acid, B12 and B6 helps prevent diabetic blindness and vision loss.	Excessive vitamin B6 produces painful, disfiguring dermatological lesions.	Bendich and Cohen, 1990; Ellis et al., 1991; McCormick, 2006.
12.	Vitamin C	Fruit and vegetables	Ascorbic acid	Endothelial cells	Improves insulin stimulated glucose metabolism.	May raise blood sugar level.	Paolisso et al., 1994; 1995.
13.	Vitamin E	Vegetable oil, sunflower, nuts, whole grain, green leafy avocado, carrot, peanuts, almond, hazelnuts.	Tocopherol	Kidney, brain, muscles, heart and lung.	Produces a significant improvement in insulin mediated glucose utilization in healthy people and type-2 diabetics.	Large doses of α-tocopherol are known to deplete plasma and tissue γ-tocopherol.	Paolisso et al., 1993; Barbagallo et al., 1999; Jiang et al., 2001.
14.	Zinc	Minerals	Zinc (picolinate)	Immune and metabolic cells.	Assists normal production, storage and secretion of insulin, necessary for the conformational integrity of insulin, helps blood sugar get into cells.	Significantly higher doses may cause nausea, vomiting, headache and drowsiness.	Paolisso et al., 1993; Barbagallo et al., 1999; Jiang et al., 2001.
15.	Copper	Oat, bran, apple, almond.	Copper picolinate	Pancreas, blood vessels and nerves.	Protects pancreatic cells, prevents diabetes-related damage to blood vessels and nerves and lowers blood sugar levels.	Health benefits impaired by high intake of zinc.	Johnson et al., 1998; Sitasawad et al., 2001.