Coenzyme Q10

Coenzyme Q10 is an antioxidant and protects against free radical damage.

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Coenzyme Q10, which is also known as ubiquinone, is one form of a substance known as coenzyme Q, which is found in all plant and animal cells. Coenzyme Q10 is the form used for energy production in humans and it can be made from some of the other forms of coenzyme Q in your diet. Coenzyme Q10 was identified in 1957.

What it does in the body

Energy production

Coenzyme Q10 is involved in energy production in cells. It is necessary for the formation of adenosine triphosphate (ATP), a compound that acts as an energy donor in chemical reactions. Coenzyme Q10 is mobile in cell membranes and functions in the transfer of energy and oxygen between blood and body cells and between cell components.

Antioxidant properties

Coenzyme Q10 is an antioxidant and protects against free radical damage to cell structures and other substances in the body. It works together with vitamin E and may protect vitamin E from damage.

Absorption

Plasma levels of coenzyme Q10 are higher in vegetarians. Coenzyme Q10 levels appear to decline with age.

Deficiency

Although coenzyme Q10 can be made in the body, deficiency states can occur. They may be caused by nutritional deficiencies, a genetic or acquired defect in synthesis or because of increased tissue needs due to a medical condition such as heart disease. Coenzyme Q10 deficiency can worsen or cause many disease conditions. Older people in general may need more coenzyme Q10, as levels of this vital nutrient appear to decline with age. As the heart is one of the most metabolically active tissues in the body and requires a large amount of ATP to function efficiently, coenzyme Q10 deficiency seriously affects the heart. Deficiency has also been linked to a wide range of other conditions including cancer, muscular dystrophy, diabetes, obesity, periodontal disease, lowered immune function, and neuro degenerative disorders such as Parkinson's disease.

Sources

Coenzyme Q is found in all plant and animal cells. Some coenzyme Q10 is made in the body, particularly in the liver, and some is obtained from food. The production process is a complex one involving around 15 different reactions. It is not clear how much coenzyme Q10 from the diet contributes to body stores, but evidence suggests that dietary coenzyme Q10 is an important source. The average person may consume around 5 mg of coenzyme Q10 per day. The main sources are meat, fish and vegetable oils. Soybean, sesame and canola oils are high in coenzyme Q10. Wheat germ, rice bran and soybeans contain reasonable amounts of coenzyme Q10, but vegetables contain relatively little; although spinach and broccoli may be quite good sources.

Supplements

Coenzyme Q10 is available in tablets and capsules. Oil-based supplements may be the best-absorbed form. The amount of coenzyme Q10 available from dietary sources is likely to be insufficient to produce the clinical effects of high dose coenzyme Q10. Coenzyme Q10 may take up to four to eight weeks to build up to peak concentration in the body, and it may take several weeks of daily dosing to see noticeable effects.

Toxic effects

No toxic effects have been reported, even at high doses. Therapeutic uses of supplements

Cardiovascular disease

Increasing scientific evidence suggests that coenzyme Q10 is a safe and effective therapy for a wide range of cardiovascular diseases such as congestive heart failure, cardiomyopathy, high blood pressure, mitral valve prolapse and angina. It has also been used to treat patients undergoing coronary artery bypass surgery. Coenzyme Q10 appears to exert its beneficial effects both by improving energy production and by acting as an antioxidant. In a study published in 1994, researchers at the University of Texas Karl looked at the usefulness of long-term coenzyme Q10 therapy in clinical cardiology. Over an eight-year period, they treated 424 patients with various forms of cardiovascular disease by adding coenzyme Q10, in amounts ranging from 75 to 600 mg/day to their treatment programs.

Patients were divided into six diagnostic categories including ischemic cardiomyopathy, dilated cardiomyopathy, primary diastolic dysfunction, hypertension, mitral valve prolapse and valvular heart disease. The patients were followed for an average of 17.8 months. The researchers evaluated clinical response according to the New York Heart Association (NYHA) functional scale and found significant improvements in all the patients. Out of 424 patients, 58 per cent improved by one NYHA class, 28 per cent by two classes and 1.2 per cent by three classes. Statistically significant improvements in heart muscle function were shown using a variety of laboratory tests. Before treatment with coenzyme Q10, most patients were taking from one to five cardiac medications, and during the study, overall medication requirements dropped considerably with 43 per cent of patients stopping between one and three drugs. Only 6 per cent of the patients required the addition of one drug. No apparent side effects from coenzyme Q10 treatment were noted other than a single case of transient nausea. The researchers concluded that coenzyme Q10 is a safe and effective treatment for a broad range of cardiovascular diseases, often in combination with other medications, as it produces improvements in a variety of symptoms and reduces medication needs.

Heart failure

Biopsy samples from patients undergoing cardiac surgery and blood samples from patients with congestive heart failure suggest that mitochondrial dysfunction and energy starvation caused by coenzyme Q10 deficiency contributes to heart failure. The improved cardiac function in patients with congestive heart failure treated with coenzyme Q10 supports this theory.

Several controlled studies using coenzyme Q10 in patients with heart failure have been published. The main clinical problems in patients with congestive heart failure are the frequent need of hospitalisation and the high incidence of life-threatening complications. In an Italian study published in 1994 researchers investigated the safety and clinical effectiveness of coenzyme Q10 in treating congestive heart failure that had been diagnosed at least six months previously and treated with standard therapy including digitalis, diuretics and vasodilators. This study involved 2664 patients in NYHA classes I and II, and most of them received 100 mg per day of coenzyme Q10. After three months of treatment, improvement in at least three symptoms was seen in 54 per cent of patients, which the researchers interpreted, as indicating an improved quality of life.

Hypertension

Coenzyme Q10 deficiency is often seen in patients with hypertension, and several studies have shown beneficial effects of coenzyme Q10 supplements. In a 1994 study, 109 patients with hypertension were treated with an average dose of 225 mg of coenzyme Q10 per day in addition to their existing anti-hypertensive drugs. Most of these patients had been diagnosed with hypertension for a year or more before the study started. Results showed a definite and gradual improvement in symptoms and a reduced need for medication within the first one to six months. Fifty one per cent of patients came off between one and three anti-hypertensive drugs about four months after starting coenzyme Q10 therapy. After this period, blood pressure and medication needs stabilized. Echocardiograms were performed on 39 per cent of the patients at the beginning of the study and during the treatment. In 9.4 per cent of cases, highly significant improvements were seen.

In another study, 26 patients with essential arterial hypertension were treated with 50 mg of coenzyme Q10, twice daily for ten weeks. Blood plasma levels of coenzyme Q10, blood serum total and beneficial HDL cholesterol, and blood pressure were determined in all patients before and at the end of the ten-week period. At the end of the treatment, average systolic blood pressure decreased from 164.5 to 146.7 mmHg and diastolic blood pressure decreased from 98.1 to 86.1 mmHg. Serum total cholesterol decreased from 222.9 mg/dl to 213.3 mg/dl and serum HDL cholesterol increased from 41.1 mg/dl to 43.1 mg/dl. The researchers also used a test to measure the resistance to blood flow in peripheral blood vessels which showed significant improvements. The results from this study suggest that coenzyme Q10 lowers cholesterol and decreases blood pressure by opening up blood vessels and reducing the resistance to blood flow.

Cardiomyopathy

Cardiomyopathy is the term used for any disease, which affects the structure and function of the heart. Coenzyme Q10 deficiency is often found in blood and heart muscle of cardiomyopathy sufferers, and several studies have shown that therapy with coenzyme Q10 produces improvements in heart function as it improves energy production in the muscle. In a 1997 study, seven patients with hypertrophic cardiomyopathy were treated with an average of 200 mg/day of coenzyme Q10. All patients noted improvement in symptoms of fatigue and shortness of breath.

Atherosclerosis

Coenzyme Q10 may help prevent atherosclerosis as it can protect against oxidative damage to fats. In a 1993 Japanese study, researchers measured levels of coenzyme and also levels of various types of cholesterol and other blood fats in 378 people. These included 249 people with no coronary artery disease, 29 patients with the disease who were receiving pravastatin, (a cholesterol-lowering drug) and 104 patients with the disease who were not receiving pravastatin. In the patient groups, the plasma total cholesterol and LDL cholesterol levels were higher and the plasma coenzyme Q10 level lower than in those with no disease.

The researchers found that coenzyme Q10 levels, either alone or when expressed in relation to LDL levels, were significantly lower in the patient groups compared with those with no disease. They concluded that coenzyme Q10 therapy would be beneficial in patients with atherosclerosis.

Heart surgery

Coenzyme Q10 may help to prevent 'ischemia reperfusion injury', one of the main problems that occurs in coronary artery bypass surgery. This term refers to the oxygen-induced damage caused when the blood supply is returned to the heart and arteries after having been cut off during surgery. The heart muscle and the linings of the arteries suffer, and this greatly increases the risk of subsequent coronary artery disease.

A number of medical studies have shown that giving patients coenzyme Q10 supplements before surgery can reduce the damage caused when blood flow is returned. In a 1996 study, 30 patients due to undergo elective surgery for heart disease were randomly divided into two groups. Patients in group I received 150 mg of coenzyme Q10 for seven days before the operation and those in group II received a placebo. Scientists then assessed the amount of oxidative damage by measuring the levels of certain enzymes and chemicals during the surgery. Results showed that those patients who had taken coenzyme Q10 suffered less damage than those who had not.

Angina

Some small studies have shown that coenzyme Q10 supplements can be beneficial in the treatment of angina. In a 1985 Japanese, double-blind, placebo-controlled, randomised, crossover study, the effects of coenzyme Q10 on exercise performance were studied in 12 patients, average age 56 years, with stable angina pectoris. The study involved multistage treadmill exercise tests. The patients were given three daily doses of 50 mg of coenzyme Q10 for four weeks, and results showed a reduction in frequency of angina attacks from 5.3 to 2.5 attacks for two weeks. Consumption of the angina medication, nitro-glycerine, was also reduced.

Cancer

As an antioxidant, coenzyme Q10 may have a role to play in both cancer prevention and cancer treatment. In a 1994 study, 32 breast cancer patients, aged 32 to 81 years and classified 'high risk' due to the spread of their tumours to the lymph nodes in their armpits, were studied for 18 months following an Adjuvant Nutritional Intervention in Cancer (ANICA) protocol. This nutritional protocol was added to the surgical and therapeutic treatment of breast cancer and involved treatment with a combination of nutritional antioxidants, (vitamin C: 2850 mg, vitamin E: 2500 IU, beta carotene 32.5 IU, selenium 387 mcg plus secondary vitamins and minerals) essential fatty acids, (1.2 g gamma-linolenic acid and 3.5g of omega-3 fatty acids) and 90 mg of coenzyme Q10 per day.

The researchers measured various biochemical markers of cancer progression, tumour spread and the clinical condition of the patients. Quality of life and survival were also assessed during the trial. The main observations were that none of the patients died during the study period. (The expected number was four); none of the patients showed signs of further distant metastases; quality of life was improved (no weight loss, reduced use of pain killers); six patients showed apparent partial remission.

In one of these six cases, the dosage of coenzyme Q10 was increased to 390 mg. In one month, the tumour was no longer palpable and in another month, mammography confirmed that the tumour had disappeared. Encouraged by these results, the researchers gave 300 mg a day of coenzyme Q10 to another patient who had been surgically treated but still had evidence of some tumour remaining. After three months, the patient was in excellent clinical condition and there was no residual tumour tissue.

Periodontal disease

The treatment of periodontal disease with coenzyme Q10 is controversial and research has produced mixed results, but there have been positive outcomes in some studies.

Muscular dystrophy

Deficiency of coenzyme Q10 has been found in the mitochondria of the muscle tissue of patients with muscular dystrophy. Two double-blind trials have been carried out involving patients with muscular dystrophies. The first trial involved 12 patients, ranging from 7 to 69 years of age, with diseases including the Duchenne, Becker, and the limb-girdle dystrophies; myotonic dystrophy; Charcot-Marie-Tooth disease; and the Welander disease. The coenzyme Q10 blood levels in these patients were low at the beginning of the study. The patients were then treated for three months with 100 mg daily of coenzyme Q10 or a matching placebo. The second double-blind trial was similar, and involved 15 patients having the same categories of disease. Since heart disease is known to be associated with these muscle diseases, cardiac function was also monitored. The researchers recorded definite improvements in physical performance in both studies.

Exercise

Due to its role in energy production, coenzyme Q10 has also been used to enhance athletic performance. Because exercise increases the risk of oxidative damage, coenzyme Q10 as an antioxidant may have a role to play in protection from such damage. In a 1997 study done in Finland, the effects of coenzyme Q10 supplements were studied in a double-blind cross-over study of 25 cross-country skiers. The results showed that all measured indexes of physical performance improved significantly. Ninety-four per cent of the athletes felt that the supplements had been beneficial in improving their performance and recovery time, whereas only 33 per cent of those in the placebo group did. Other uses Coenzyme Q10 may be beneficial in patients with diabetes and may help improve diabetic control. Coenzyme Q10 levels have also been shown to be low in obese people, and when combined with a low-calorie diet coenzyme Q10 may speed up weight loss. Coenzyme Q10 has also been used to treat the neurological disorder, Huntington's chorea, and to improve sperm function and motility.

Interactions with other nutrients

Coenzyme Q10 synthesis requires vitamins B6, C, B12, folic acid, riboflavin, niacin, and pantothenic acid.

Interactions with drugs

Several different types of medications have side effects that include adverse effects on heart function. Some of these drugs, such as doxorubicin, have effects on the heart that are so severe that the amount of time for which they can be used is strictly limited. Research has shown that the toxic effect of doxorubicin is due to its inhibitory effects on coenzyme Q10-dependent enzyme systems. Coenzyme Q10 reduces the toxic effects of doxorubicin on the heart. Another class of drugs, known as beta blockers, which are used to treat high blood pressure and some other types of cardiovascular disease, have been shown to interfere with the production and function of coenzyme Q10, and to adversely affect heart function. This may explain why, in some cases, long-term therapy with beta blockers can lead to congestive heart failure. Coenzyme Q10 therapy in combination with beta blockers may be beneficial.

In recent years, the drugs lovastatin, pravastatin, and simvastatin have become widely used to treat high blood cholesterol. These medications work by inhibiting an enzyme known as HMG-CoA reductase, and they are very effective in lowering cholesterol levels. However, this enzyme is also responsible for production of coenzyme Q10. Because of this, the cholesterol-lowering effect of these drugs is accompanied by an equivalent lowering of coenzyme Q10 levels. In patients with existing heart failure, lovastatin has been shown to cause increased heart disease with life-threatening results in some patients. Coenzyme Q10 supplements may help to prevent some of the adverse effects of these widely used drugs.

Others drugs, such as phenothiazine neuroleptics and tricyclic antidepressants, also have effects on heart function, which seem to be related to inhibition of coenzyme Q10 function.