Amino acids and their significance for diabetes
Arginine can reduce insulin resistance
Diabetics cannot sufficiently utilise carbohydrates such as sugar, which is an important energy source. Insulin plays a significant role here as it is a blood-sugar reducing endogenous hormone and the production of insulin is lower in those affected. Furthermore, the cells in their bodies are not able to properly absorb the insulin that is available. The reason for this is the highly diminished sensitivity of the cells towards insulin. The cell membranes are unable to recognise the hormone and therefore do not absorb enough of it. The consequence of this so-called insulin resistance is that not enough energy is produced in the cells. Moreover, sugar cannot properly be degraded in the blood and therefore accumulates so that the blood sugar level increases. Over the long-term, a constantly elevated blood sugar level can damage the vessels and lead to calcification and typical resulting illnesses such as stroke or heart attack. Diabetes mellitus type 2 is mostly associated with older people, as the insulin sensitivity in the cells decreases with age. A well-received study from 1998 showed that arginine can reduce insulin resistance, meaning in turn that insulin sensitivity can be increased.1
Arginine - an important amino acid for insulin absorption
Another study by European researchers showed that the amino acid arginine is of great importance for the sensitivity of the body’s cells towards insulin. Arginine is a precursor of nitrogen oxide, a transmitting substance which has a direct influence on insulin sensitivity. For the study, six type two diabetes patients were split into two groups. Both groups consumed a normal diabetic diet. One of the groups was administered a placebo to be taken three times daily for one month. The other group was administered arginine over the same time period. The insulin sensitivity levels in the patients were regularly tested by scientists throughout the course of the study. Results were conclusive and showed that arginine improved the insulin sensitivity by more than 30 percent when compared to the placebo group. Arginine furthermore led to a considerable expansion of the blood vessels, allowing for the blood pressure in the patients to be reduced significantly.2 Two studies from 2013 have reached a similar conclusion.3,4 Another study has shown that arginine is also important in the treatment of diabetes-related foot diseases.5
Carnitine - a useful supplement in the treatment of diabetes
A study carried out in 2007 was able to prove that the amino acid L-carnitine can improve insulin sensitivity in the treatment of diabetes, when taken as a dietary supplement.6 An additional intake of carnitine can also offer other advantages to diabetics, as was shown by a study carried out in 20097 for instance, in which LDL cholesterol levels in diabetics were reduced. Furthermore, carnitine protects the cells in the body from oxidative stress. Oxidative stress is triggered by free radicals which come into being through particular metabolic processes but also though environmental pollution, smoking or UV rays. Free radicals can damage cell membranes and various surface structures in the body, such as the inner walls of the arteries. This is why they are often involved in the development of cardiovascular diseases. Diabetics already have a higher risk of cardiovascular, kidney and eye diseases because the increased blood sugar attacks the blood vessels. Oxidative stress increases this effect. Carnitine can make free radicals harmless and thereby protect the heart, kidneys and eyes.8
Carnitine improves blood lipid values
Lipoprotein A is a component of blood fat. If the concentration of this substance in the blood plasma increases, the risk of coronary heart disease or circulatory disorders increases with it. One study showed that the administration of carnitine could lower this risk. 94 patients suffering from type 2 diabetes with increased lipid values were split into two groups. Both groups consumed a strict diabetic diet. The participants of the main group were also administered a placebo and the other group took a gram of carnitine daily, in tablet form. The intake of carnitine led to a significant decrease of the level of lipoprotein A in the blood plasma of the participants, both after three and six month intervals. Even though this particular study is actually only preliminary, a clear tendency for the protective properties of carnitine has already become apparent.9
Zinc regulates insulin secretion
The trace element zinc also plays a significant role in the insulin cycle. It is a component of insulin and is necessary for the storage and effect of the hormone. Zinc is furthermore a component of many important enzymes which are involved in the regulation of the glucose balance in the body. It controls the release of insulin after eating, for instance. The supply of zinc in the UK is not sufficient, as is the case in many other countries in Europe and is below the RDA of 12-15mg. Diabetics are more likely to suffer from zinc sufficiency than non-diabetics. This is why they are more likely to suffer from reduced insulin secretion.
Zinc stabilises blood sugar
A regular intake of zinc over a period of a few weeks in diabetic patients activates the remaining insulin production and stabilises the blood sugar levels. At the same time it reduces fasting blood glucose levels which are determined by the so-called glycohaemoglobin in diabetics. Zinc also has a positive effect with regards to the healing of wounds. This is why a supplement of it is useful in the treatment of diabetic gangrene.
An daily intake of 15 to 30mg of zinc is advisable within the framework of prevention and treatment of diabetes. A proportion of this should be taken in the form of a dietary supplement.10
Lutein and zeaxanthin strengthen the eyesight of diabetics
The increasing calcification of the arteries mainly affects the eyes, especially in diabetics. This is why a supplementary intake of the secondary plant metabolite lutein should be of particular interest to diabetics. A study from the USA showed that lutein can ease the symptoms of a macular degeneration in the early stages, where the retina gradually loses its function. For the study, 90 patients with a macular degeneration were divided into three groups. One group were administered 10mg of lutein per day for a year, another group was given a combination of lutein with other antioxidative vitamins and minerals and a control group were given a placebo. No changes were witnessed in the placebo group, but patients in the lutein and combination treatment groups experienced improved eyesight.
Although these results still have to be tested on larger groups and over a longer period of time, a considerable positive effect of anti-oxidative nutrients, especially lutein, has certainly become apparent in eye health.11
It is especially important for diabetics to prevent unnecessary strain to the eyes and to ensure a sufficient supply of micronutrients. This particularly applies to the nutrients which cannot be produced in the body such as the carotenoid lutein and zeaxanthin. They protect the eyes in two ways as they act like an internal pair of sunglasses in front of the sensitive retina and filter out the harmful rays. If the harmful UV or other rays are nevertheless able to reach the eye, triggering the formation of free radicals, the second protective feature comes into effect. The micronutrients connect the free radicals and make them safe.12 This double protection through filtering and capturing radicals deteriorates quickly in diabetics, which is why those affected should particularly ensure they have a sufficient supply of the necessary nutrients.
Those who consume five portions of fruit and vegetables a day, depending on levels of freshness and preparation method, should have a sufficient intake of micronutrients. Nevertheless, these daily amounts are not always practical and nutritional supplements offer a sensible alternative for they permit a regular supply of all of the necessary micronutrients. Lutein and zeaxanthin are natural nutrients and are completely safe. Unfortunately production is currently relatively costly, which is why the price for respective dietary supplements is usually quite high.
1Krishna Mohan, I. & Das, U.N. (1998) Effect of L-arginine-nitric oxide system on chemical-induced diabetes mellitus, Free Radical Biology and Medicine, Volume 25, issue 7, (pp. 757-765)
2Piatti, P.M., Monti, L.D., Valsecchi, G., Magni, F., Setola, E., Marchesi, F., Galli-Kienle, M., Pozza, G. & Alberti, K.G.M.M. (2001) Long-term oral L-arginine administration improves peripheral and hepatic insulin sensitivity in type 2 diabetic patients, Diabetes Care, Volume 24, issue 5, (pp. 875-880)
3Hoang, H. H., Padgham, S. V., & Meininger, C. J. (2013) L-arginine, tetrahydrobiopterin, nitric oxide and diabetes, Current Opinion in Clinical Nutrition & Metabolic Care, Volume 16, issue 1, (pp. 76-82)
4Rajapakse, N. W., Chong, A. L., Zhang, W. Z., & Kaye, D. M. (2013) Insulin-Mediated Activation of the L-Arginine Nitric Oxide Pathway in Man, and Its Impairment in Diabetes, PloS one, Volume 8, issue 5
5Arana, V., Paz, Y., González, A., Méndez, V., Méndez, J.D. (2004) Healing of diabetic foot ulcers in L-arginine-treated patients, Biomed Pharmacother, Volume 58, (pp. 588-597)
6Power, R.A., Hulver, M.W., Zhang, J.Y., Dubois, J., Marchand, R.M., Ilkayeva, O., Muoio, D.M. & Mynatt, R.L. (2007) Carnitine revisted: potential use as adjunctive treatment, Diabetes Diabetologia, Volume 50, issue 4, (pp. 824-832)
7Malaguarnera, M., Vacante, M., Avitabile, T., Cammalleri, L. & Motta, M. (2009) L-carnitine supplementation reduces oxidized LDL cholesterol in patients with diabetes, American Journal of Clinical Nutrition, Volume 89, issue 1, (pp. 71-76)
8Löster, H. & Böhm, U. (2000) L-crnitine reduces malondialdehyde concentrations in isolated hearts in dependence on perfusion conditions, Molecular and Cellular Biochemistry, issue 217, (pp. 83-90)
9Derosa, G., Cicero, F.G., Gaddi, A., Mugellini, A. Ciccarelli, L. & Fogari, R. (2003) The effect of L-carnitine on plasma lipoprotein(a) levels in hyperchol esterolemic patients with type 2 diabetes mellitus, Clinical Therapeutics, Volume 25, issue 5, (pp. 1429-1439)
10Niewoehner, C.B., Allen, J.I., Boosalis, M., Levine, A.S. & Morley, J.E. (1986) Role of zinc supplementation in type II diabetes mellitus, American Journal of Medicine, Volume 81, issue 1, (pp. 63-68)
11Richer, S., Stiles, W., Statkute, L., Pulido, J., Fraukowski, J., Rudy, D., Pei, K., Tsipursky, M. & Nyland, J. (2004) Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation Trial), Optometry Journal of the American Optometrid Association, Volume 75, issue 4, (pp. 216-229)
12Semba, R.D. & Dagnelie, G. (2003) Are lutein and zeaxanthin conditionally essential nutrients for eye health?, Medical Hypotheses, Volume 61, issue 4, (pp. 465-472)