The Mitochondrial Theory of Aging

The mitochondrial theory of aging (MTA) and the free-radical theory of aging (FRTA) are closely related, and were in fact proposed by the same researcher about 20 years apart. Both theories suggest that free-radicals damage DNA over time, causing one to age, while the MTA just adds the mitochondria and its production of free radicals into the equation. These theories and the understanding we now have of free radicals are the reason that antioxidants are such popular supplements and topics of discussion today.

The Paradox

Mitochondria are like little cells within our cells (see Figure 1 ). They are the energy producing organelles of the body. The more energy a certain tissue requires such as the brain and the heart, the more mitochondria those cells contain. What makes mitochondria interesting is that they have their own set of DNA. What makes them paradoxical is that the more energy they produce, the more DNA-damaging free radicals they produce! Mitochondrial DNA damage appears to be caused by the natural by-products of energy or ATP production, meaning that the very process that is meant to sustain life is what eventually causes the dysfunction and death of the cell! Mitochondria may well hold the key to function and dysfunction, and ultimately to life and death!Think of it this way: all cells, tissues and thus body parts require ATP, or energy, to function properly. If DNA holds the blueprint for the proper function of a cell, then any change in the blueprint will change how the cell functions. If the mitochondria do not function properly, then they cannot fulfill their role in producing energy, meaning that the cell will lose its ability to function adequately.

Many Mechanisms

Researchers have mostly focused on those related to the heart and the brain because they require large amounts of oxygen and energy and are so dense in mitochondria, meaning that mitochondrial dysfunction has a huge impact on the functioning of these organs.

Toxic Fat

Mitochondria are also involved in lipid metabolism. If the mitochondria are dysfunctional, then lipid metabolism becomes imbalanced. In humans, a high-fat diet has been shown to increase mitochondrial production of free radicals in muscles, and that when free radical production was limited with a targeted drug, insulin sensitivity was preserved!⁶

Calcium Regulation

Dysfunctional mitochondria are also a hallmark of heart muscle remodeling in disease. It is now thought that mitochondria help regulate calcium flux in the heart cells, helping to regulate its function.^7,8 Calcium is required for the contraction of muscles, including the heart. If the mitochondria are dysfunctional, their ability to buffer calcium as well as supply energy to the heart are greatly compromised.

Potential Treatment Options Under Study

Exercise for Endothelial and Mitochondrial Dysfunction

It is known that exercise can actually stimulate the multiplication of mitochondria in muscle tissue. This makes sense because if the muscles require more energy, the body will need to make sure the machinery to make that extra energy is available. We also know that exercise improves endothelial function.

Nutritional Support for the Mitochondria

1. Lipoic Acid & Acetyl-L-Carnitine

Calcification of the blood vessels is an important concern today because it leads to hardening of the arteries. Alpha lipoic acid is known to be a mitochondrial antioxidant that preserves or improves mitochondrial function. However, it has now also been shown in vitro and in an animal study that lipoic acid can prevent arterial calcification, and that arterial calcification may even be related to mitochondrial dysfunction!¹² Since lipoic acid is so important for mitochondrial health, methods are under study to increase lipoic acid synthase production, the enzyme responsible for making lipoic acid in the body.¹¹

2. Co-Enzyme Q10

CoQ10 is perhaps the most popular mitochondrial enzyme and antioxidant. It is already well known that statin drugs taken for high cholesterol severely reduce CoQ10 levels, which ironically Advances 23causes other negative cardiovascular side effects.

3. Other Mitochondrial Antioxidants

Other natural compounds that have been shown to have antioxidant effects in the mitochondria include resveratrol, found in wine and grapes, curcumin from turmeric and EGCG, found abundantly in green tea extract. However, human studies have not been conducted for these compounds in mitochondrial dysfunction.^16,18

A New Name

So recognized is the role of mitochondrial dysfunction in many diseases that a new term has been coined for this phenomenon: bioenergetic dysfunction.¹⁵

Quality Mitochondria Equals Quality Health

Not only the quantity of mitochondria but the quality of those mitochondria is important for good health. Exercise can increase the number of mitochondria, but the health of those mitochondria must be preserved with targeted mitochondrial antioxidants. Failure to do so can result in mutations to the mitochondrial DNA. The mitochondria need to be functioning adequately enough to destroy damaged or mutated machinery (mitophagy) in order to remain healthy. In fact, this regulated recycling process is essential in order to lengthen one’s lifespan according to the caloric restriction diet (which by the way is the only proven method to lengthen one’s lifespan and healthspan).¹⁵ The bottom line is that all evidence is pointing toward the mitochondria as the key holders to health.

References

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11. Padmalayam I. Targeting mitochondrial oxidative stress through lipoic acid synthase: a novel strategy to manage diabetic cardiovascular disease. Cardiovasc Hematol Agents Med Chem. 2012 Sep;10(3):223-33.

12. Kim H, Kim HJ, Lee K, Kim JM, Kim HS, Kim JR, Ha CM, Choi YK, Lee SJ, Kim JY, Harris RA, Jeong D, Lee IK. α-Lipoic acid attenuates vascular calcification via reversal of mitochondrial function and restoration of Gas6/Axl/Akt survival pathway. J Cell Mol Med. 2012 Feb;16(2):273-86.

13. McMackin CJ, Widlansky ME, Hamburg NM, Huang AL, Weller S, Holbrook M, Gokce N, Hagen TM, Keaney JF Jr, Vita JA. Effect of combined treatment with alpha-Lipoic acid and acetyl-L-carnitine on vascular function and blood pressure in patients with coronary artery disease. J Clin Hypertens (Greenwich). 2007 Apr;9(4):249-55.

14. Dai YL, Luk TH, Yiu KH, Wang M, Yip PM, Lee SW, Li SW, Tam S, Fong B, Lau CP, Siu CW, Tse HF. Reversal of mitochondrial dysfunction by coenzyme Q10 supplement improves endothelial function in patients with ischaemic left ventricular systolic dysfunction: a randomized controlled trial. Atherosclerosis. 2011 Jun;216(2):395-401.

15. Hill BG, Benavides GA, Lancaster JR, Ballinger S, Dell’italia L, Zhang J, Darley-Usmar VM. Integration of cellular bioenergetics with mitochondrial quality control and autophagy. Biol Chem. 2012 Jun 23.

16. Kang J, Pervaiz S. Mitochondria: redox metabolism and dysfunction. Biochem Res Int. 2012.

17. Davis RE, Williams M. Mitochondrial function and dysfunction: an update. J Pharmacol Exp Ther. 2012 Sep;342(3):598-607.18. Rimbaud S, Ruiz M, Piquereau J, Mateo P, Fortin D, Veksler V, Garnier A, Ventura-Clapier R. Resveratrol improves survival, hemodynamics and energetics in a rat model of hypertension leading to heart failure. PLoS One. 2011;6(10):e26391