Blood Glucose Regulation
We typically think of the pancreas with respect to blood glucose but the liver is key to regulating this important nutrient. In response to the pancreatic hormones insulin and glucagon, the liver stores excess glucose as glycogen and then breaks that glycogen down to release glucose as required. When carbohydrate intake is low, the liver makes glucose from starting material such as amino acids (the process of gluconeogenesis). The liver very quickly removes insulin from the bloodstream. This allows for rapid control of insulin levels. Swings in blood glucose would be much more dramatic without a functioning liver.
Liver damage and Type 2 Diabetes are connected with each increasing the risk of the other (1). More than half of people with Type 2 Diabetes also have non-alcoholic fatty liver disease. These health conditions share risk factors such as obesity, high blood pressure and high cholesterol.
Ketogenesis
The popular ketogenic diets rely on the liver’s ability to produce ketones. When carbohydrates are restricted tissues still need an energy source. While fat can provide energy for some tissues, others—quite notably the brain-— cannot use fat directly. The liver will produce ketones and secrete them into the blood. The ketones can be utilized by many tissues including skeletal muscle, the heart and the brain. Interestingly, the liver itself is not able to use ketones for energy! It also turns out that cancer cells are not good at using ketones for energy. For this reason, ketogenic diets are being researched as an adjunct to cancer treatment (2).
Glutathione
The liver is a factory, synthesizing many substances for the body. One of these is the tripeptide glutathione. Glutathione is made from cysteine, glycine and glutamic acid. Glutathione is an extraordinary antioxidant that is present in surprisingly high concentrations inside the cell (concentrations can be as high as that of glucose). Glutathione depletion is linked with many diverse health conditions including Alzheimer’s, asthma and autoimmune disease. Decreased glutathione may be involved in the aging process itself (3). Glutathione supplements are often poorly absorbed, although liposomal delivery improves this. The lipid covering protects the glutathione from being broken down in our G.I. tract. Natural production of glutathione can be increased by supplementing N-acetyl cysteine, omega-3 fatty acids, riboflavin, Vitamin C and Vitamin E (4).
A Connection with Growth Hormone
In response to growth hormone, the liver synthesizes insulin-like growth factor 1 (IGF-1). Many of the effects that are attributed to growth hormone are actually the result of IGF-1. These effects include stimulating growth of bone and other tissues and promoting production of lean muscle mass. IGF-1 also plays a role in glucose and lipid metabolism. Low IGF-1 levels are associated with increased risk of metabolic syndrome (5) as well as an increased risk of cardiovascular disease (6). Patients with non-alcoholic fatty liver disease have decreased IGF-1 levels. Since 80% of IGF-1 is made by the liver, clearly there is a connection between liver health and both cardiovascular and metabolic health.
Be Kind to Your Liver
Our livers suffer many kinds of assaults daily. Alcohol is the best known substance that damages the liver. However, assaults on the liver range from poor diet to toxins to medications. A key dietary concern is high sugar intake (from sucrose and high fructose corn syrup). High sugar intake is implicated in non-alcoholic fatty liver (7). A common medication that causes liver damage is acetaminophen (Tylenol).
The liver has a remarkable ability to cope with all of these assaults. It can even regenerate itself as long as it is not scarred as in cirrhosis. Early stages of liver disease can be reversed with lifestyle changes such as improved diet, avoiding alcohol, increasing exercise and maintaining a healthy weight.
Take care of your liver and your liver will take care of you.
IHN students go through a full analysis of the functions of the liver in our Body Metabolism course; one of the 19 unique courses that make up IHN’s Applied Holistic Nutrition Diploma Program.
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References:
- Tanase DM, Gosav EM, Costea CF, Ciocoiu M, Lacatusu CM, Maranduca MA, Ouatu A, Floria M. The Intricate Relationship between Type 2 Diabetes Mellitus (T2DM), Insulin Resistance (IR), and Nonalcoholic Fatty Liver Disease (NAFLD). J Diabetes Res. 2020 Jul 31;2020:3920196. doi: 10.1155/2020/3920196. PMID: 32832560; PMCID: PMC7424491.
- Barrea L, Caprio M, Tuccinardi D, Moriconi E, Di Renzo L, Muscogiuri G, Colao A, Savastano S; Obesity Programs of nutrition, Education, Research and Assessment (OPERA) group. Could ketogenic diet “starve” cancer? Emerging evidence. Crit Rev Food Sci Nutr. 2022;62(7):1800-1821. doi: 10.1080/10408398.2020.1847030. Epub 2020 Dec 4. PMID: 33274644.
- Pizzorno J. Glutathione! Integr Med (Encinitas). 2014 Feb;13(1):8-12. PMID: 26770075; PMCID: PMC4684116.
- Minich DM, Brown BI. A Review of Dietary (Phyto)Nutrients for Glutathione Support. Nutrients. 2019 Sep 3;11(9):2073. doi: 10.3390/nu11092073. PMID: 31484368; PMCID: PMC6770193.
- Aguirre GA, De Ita JR, de la Garza RG, Castilla-Cortazar I. Insulin-like growth factor-1 deficiency and metabolic syndrome. J Transl Med. 2016 Jan 6;14:3. doi: 10.1186/s12967-015-0762-z. PMID: 26733412; PMCID: PMC4702316.
- Obradovic M, Zafirovic S, Soskic S, Stanimirovic J, Trpkovic A, Jevremovic D, Isenovic ER. Effects of IGF-1 on the Cardiovascular System. Curr Pharm Des. 2019;25(35):3715-3725. doi: 10.2174/1381612825666191106091507. PMID: 31692426.
- Jensen T, Abdelmalek MF, Sullivan S, Nadeau KJ, Green M, Roncal C, Nakagawa T, Kuwabara M, Sato Y, Kang DH, Tolan DR, Sanchez-Lozada LG, Rosen HR, Lanaspa MA, Diehl AM, Johnson RJ. Fructose and sugar: A major mediator of non-alcoholic fatty liver disease. J Hepatol. 2018 May;68(5):1063-1075. doi: 10.1016/j.jhep.2018.01.019. Epub 2018 Feb 2. PMID: 29408694; PMCID: PMC5893377.