The hormone-like substance, coenzyme Q10 (CoQ10) is synthesised by the body and stored in the mitochondria. Deficiency of the active form of CoQ10 can therefore affect the body’s ability to produce energy at the mitochondrial level. It is present in all body cells but is found in highest concentrations in the organs that use the greatest energy; these include the heart, kidneys, lungs and liver. CoQ10 is involved in production of adenosine triphosphate (ATP) which is involved in energy transfer within cells.
CoQ10 comes in two forms – ubiquinol and ubiquinone. Ubiquinone is metabolised to ubiquinol which is the antioxidant form of CoQ10. It is also the most absorbable form and accounts for 90% of the CoQ10 in the blood. Thus, choosing supplements containing the ubiquinol form is recommended.[2,3]
Ubiquinol deficiency may be caused by:
- Low levels of vitamin B6 – endogenous synthesis of the quinone nucleus of CoQ10 from tyrosine requires adequate vitamin B6, thus low levels may result in low ubiquinol levels.
- Inherited genetic mutations, such as that of the APTX gene affecting synthesis and utilisation.
- Oxidative stress due to ageing.
- Production associated with chronic illness – diabetes and cancer have been linked to low levels of ubiquinol as has heart disease. It is not clear whether low levels of ubiquinol cause these diseases or are a result of them.
- A side effect of statin treatment - some cholesterol-lowering medications inhibit the action of HMG-CoA reductase, causing a reduction in the amount of mevalonate available to make cholesterol and also CoQ10. Thus, statins can reduce the concentration of CoQ10 in the bloodstream – both the conventional form and the active form of the compound, ubiquinol. Long-term statin use has been associated with fatigue and muscle cramps.
Ubiquinol is synthesised in a similar way to the production of cholesterol, a vital component of cell membranes. In CoQ10 production, acetoacetyl-CoA is converted into mevalonate by HMG-CoA reductase. Mevalonate can be used to make either cholesterol or CoQ10, and in turn, ubiquinol.
Ubiquinol is an important antioxidant that protects cells from oxidative damage as well as assisting the regeneration of other potent antioxidants such as vitamin E. The antioxidant actions and function as a cofactor for energy production of ubiquinol make it a vital nutrient for cardiovascular health. In a study of 420 people with heart failure, treatment with CoQ10 (100mg three times daily) for two years improved symptoms and reduced their risk of morbidity due to heart problems.
The body can’t store ubiquinol, so regular use is recommended to see its benefits. Supplementing with ubiquinol appears to be well tolerated by individuals and has low toxicity.[12,13]
Foods that provide CoQ10 include organ meats and meat, oily fish, vegetables (spinach, broccoli, cauliflower, avocado), fruit (oranges clementine, persimmon), legumes and wholegrains, soybean and canola oil.
Because it is fat soluble, up to a third of the CoQ10 in vegetables and eggs can be lost during frying; CoQ10 content is not changed when cooked in water.
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