CoQ10 supplement benefit and
side effects - 30 mg 50 mg 60 mg Review of research information for heart disease, blood pressure,
antioxidant, use with statin drugs such as Lipitor and Zocor
Available in dosages including 30 mg, 50, 60 and 100 mg. Use higher dosages, such as 200 mg and 300 mg, carefully
Research studies and published clinical trials
August 2 2018 by Ray Sahelian, M.D.
CoQ10 is a naturally occurring
nutrient found in each cell of the body. This nutrient was first identified by
University of Wisconsin researchers in 1957. It is found in foods, particularly
in fish and meats. In addition to playing a significant role in the energy
system of each of our cells, CoQ10 is also believed to have antioxidant
properties and may play a role in heart health. Many who take this supplement
notice that this nutrient enhances physical energy.
Benefit and medical uses, review
Studies with CoQ10 have mostly focused on its benefit involving certain types of cardiovascular diseases, including congestive heart failure and hypertension along with benefits for certain neurodegenerative conditions. However, this nutrient has also been evaluated for high cholesterol and in diabetes. Patients with high cholesterol levels who are placed on statin drugs such as Lipitor and Zocor should take additional CoQ10 in the amount of 10 to 50 mg daily, or a few times a week, to counteract the muscle damage from statin drugs (consult with your doctor). We still have a long way to go to determine the proper clinical role and benefit of this nutrient. Thus far it appears low dose usage a few times a week is reasonable.
Dosage: There is no need form most people to take more than 30 mg a few times a week although some people do fine taking 50 mg or more for short periods of time.
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Food sources and daily intake
Meat, fish, nuts, and some oils are the richest nutritional sources, while much lower levels can be found in most dairy products, vegetables, fruits, and cereals. Large variations of CoQ10 content in some foods and food products of different geographical origin have been found. The average dietary intake is only 3-6 mg a day. Coq10 is not a vitamin but a nutrient. It is naturally made in the body. Technically, a vitamin is a substance that the body cannot synthesize or cannot synthesize enough to maintain health and physiological functioning.
for short term use and long term use
CoQ10 is available in a variety of dosages ranging from 10 mg to 300 mg per capsule. I personally believe that high doses are not needed, and may even be unhelpful or detrimental. I would not feel comfortable recommending to my patients to take more than 50 mg, or maximum 100 mg, a day, for long term use unless as a necessary treatment of a medical condition. For short term use one can take up to 300 mg a day for a few days. More is not necessarily better when it comes to certain supplements. Plus, many people who take it also take other supplements and we don't know what kind of interactions would occur with other herbs, nutrients, and prescription medications. These pills do not have to specifically be taken with oil, taking it with breakfast is a good option.
Prolonged intake of coenzyme Q10 impairs cognitive
functions in mice.
Mice were fed a diet containing low dosage or high dosage CoQ10 starting at 4 months of age. This did not affect survivorship of mice through 25 months of age. Prolonged intake in low amounts had no discernable impact on cognitive and motor functions whereas intake at higher amounts exacerbated cognitive and sensory impairments. J Nutrition 2009; Department of Pharmacology and Neuroscience, Institute for Aging and Alzheimer's Disease Research, University of North Texas Health Science Center, Fort Worth, TX, USA.
Q. I'm a 61 yr old active male and started taking 200 mgs
daily of CoQ10 three months ago. I felt an increase in energy and stamina during
cardio exercise....jogging....swimming etc within a week or so. In the past
month I reduced my dosage to 100 mgs daily after reading online content
suggesting against long term dosage at 200 mgs. I'm confused about daily dosage
for long term benefits. I can really feel a significant improvement in energy
and performance since beginning CoQ10 - which tells me I was very low on this
nutrient, and want all of the benefits to continue. Your advice on daily dosage
please is greatly appreciated.
A. Each person is different but my preference is not to use more than 50 mg a day, preferably taking a day or two off each week.
Q. Can you take supplements every second day? I am taking
Coenzyme q10 150 mg every day and I am finding it too strong. If I take it every
second day will I be missing out on its effect? I am taking it to lower blood
A. Yes, for sure. I prefer using less than 50 mg a day. It is a good idea to skip days if the supplement is too strong and even better is taking a much lower dose daily.
Benefit and studies
Anti aging and longevity
I have not seen human studies regarding the long term use of this supplement and its effect on the aging process.
Co-supplementation with vitamin E and coenzyme Q10 reduces circulating markers of inflammation indicated by the CRP concentration in healthy adult baboons. Am J Clin Nutr. 2004.
What's your opinion on the use of CoQ10 for cancer treatment or prevention?
I'm not convinced yet that it is an effective cancer treatment but I'm keeping an open mind until additional research is published.
One lab study found incubation of lenses with this nutrient reduced oxidative damage. Whether benefits could be achieved through oral supplementation remains to be seen.
reversing muscle damage
Individuals on cholesterol medicines of the statin class such as Lipitor and others, may consider taking 30 to 50 mg a few times a week since statins decrease blood CoQ10 levels.
Statin drugs, such as Lipitor and Zocor, lower cholesterol levels but at the same time they interfere with the making of coenzyme Q10 in the body. Scientists now suspect that CoQ10 deficiency may partly or fully contribute to the development of muscle damage in those on these cholesterol lowering drugs.
Depression, low mood
Q. Is there any evidence for CoQ10ís benefits for depression side of Bipolar type II, or Cyclothymia, and if paradoxically CoQ10 can in theory worsen this type of depression.
A. I have not seen research in this area. CoQ10 can improve energy levels and thus some people may find some benefit if their depression is associated with tiredness. However high doses can cause insomnia and make low mood worse. Any amount that interferes with sleep is considered a high dose. The amount varies between individuals and could range from 20 mg to more than 100 mg.
Diabetes and high
CoQ 10 may be of slight benefit in diabetics. It helps improve the function of endothelial cells lining blood vessels and may slightly help with blood sugar control.
Small doses are beneficial to fight fatigue, but high amounts may be counterproductive.
Antioxid Redox Signal. 2015. Does oral coenzyme Q10 plus NADH supplementation improve fatigue and biochemical parameters in chronic fatigue syndrome? Chronic fatigue syndrome (CFS) is a chronic and extremely debilitating illness characterized by prolonged fatigue and multiple symptoms with unknown cause, diagnostic test, or universally effective treatment. Inflammation, oxidative stress, mitochondrial dysfunction, and CoQ10 deficiency have been well documented in CFS. We conducted an 8-week, randomized, double-blind placebo-controlled trial to evaluate the benefits of oral CoQ10 (200 mg/day) plus NADH (20 mg/day) supplementation on fatigue and biochemical parameters in 73 Spanish CFS patients. A significant improvement of fatigue showing a reduction in fatigue impact scale total score was reported in treated group versus placebo. In addition, a recovery of the biochemical parameters was also reported. NAD+/NADH, CoQ10, ATP and citrate synthase were significantly higher, and lipoperoxides were significantly lower in blood mononuclear cells of the treated group. These observations lead to the hypothesis that the oral CoQ10 plus NADH supplementation could confer potential therapeutic benefits on fatigue and biochemical parameters in CFS. Larger sample trials are warranted to confirm these findings.
Antifatigue effect of coenzyme Q10 in mice.
Male mice were orally given CoQ10 in the form of Bio-Quinone (Pharma Nord, Vejle, Denmark) for 4 weeks and made to perform swimming exercise with loads attached to their tails. Treated mice treated showed a significantly prolonged exhaustive swim time, increased liver glycogen contents compared to control animals. J Med Food. 2010.
Although a couple of studies have indicated that it may be helpful in gum disease, the most important way to keep healthy gums is to remove the food particles that are stuck between teeth. This is best accomplished by brushing and flossing after every meal. You may wish to keep your toothbrush and floss by your bed at night or near your favorite sofa while watching TV before bed and thus have a reminder to floss at night. My dentist thinks it is preferable to brush before flossing.
Heart attack patients
In a trial of patients with recent myocardial infarction, CoQ10 -- used in addition to aspirin and cholesterol-lowering drugs -- decreased the likelihood of further cardiac events for at least one year after the heart attack. Effect of coenzyme Q10 on risk of atherosclerosis in patients with recent myocardial infarction. Singh RB. Mol Cell Biochem. 2003.
Heart failure benefit
CoQ10 may be helpful in heart failure, but more research is needed to find the ideal dosage range. For the time being I would suggest those with heart failure not to exceed 50 to 100 mg a day.
Several randomized controlled trials have examined the effects of CoQ10 in congestive heart failure (CHF). The objective of this meta-analysis was to evaluate its impact on the ejection fraction (EF) and New York Heart Association (NYHA) functional classification in patients with CHF. A systematic review of the literature was conducted which showed supplementation resulted in a pooled mean net change of 3.6% in the EF and −0.30 in the NYHA functional class. Subgroup analyses showed significant improvement in EF for crossover trials, trials with treatment duration ≤12 wk in length, and studies with a dose ≤100 mg CoQ10 / d and in patients with less severe CHF. Effect of coenzyme Q10 supplementation on heart failure: a meta-analysis. 2013 American Society for Nutrition.
Coenzyme Q10 and exercise training in chronic heart failure.
Eur Heart J. 2006.
We studied 23 patients in NYHA class II and III with stable CHF secondary to ischemic heart disease. Patients were assigned to each of the following treatments: oral CoQ10 100 mg tid, CoQ10 plus supervised exercise training (ET) five times a week), placebo, and placebo plus ET. Each phase lasted 4 weeks. Oral CoQ10 improves functional capacity, endothelial function, and LV contractility in CHF without any side effects. The combination resulted in higher plasma levels and more pronounced effects on all the abovementioned parameters.
Hypertension, high blood pressure
CoQ10 may help lower blood pressure by a small amount in some people.
Randomized, double-blind, placebo-controlled trial
of coenzyme Q10 in isolated systolic hypertension.
South Med J. 2001.
We conducted a 3 month randomized, double-blind, placebo-controlled trial with twice daily administration of 60 mg of oral CoQ10. The mean reduction in systolic blood pressure was 17 mm Hg. None of the patients exhibited orthostatic blood pressure changes.
It is possible that a few individuals may benefit from taking these pills, but there are many factors that influence migraine headaches and taking this supplement pill alone is not likely to have a major effect.
Efficacy of coenzyme Q10 in migraine prophylaxis: a
randomized controlled trial.
We compared CoQ10 (3 x 100 mg/day) and placebo in 42 migraine patients. It was superior to placebo for attack-frequency, headache-days and days-with-nausea in the third treatment month and well tolerated.
Open label trial of coenzyme Q10 as a migraine preventive.
Thirty-two patients (26 women, 6 men) with a history of episodic migraine with or without aura were treated at a dose of 150 mg per day. 61% of patients had a greater than 50% reduction in number of days with migraine headache.
I am 32 years old with a 10 month old daughter. My
menstrual period returned about a month after her birth and has remained on a
regular 28 day cycle. I started to take CoQ10 about a month ago 120 mg
a day after reading articles about its role in possibly preventing migraine
headaches. I havenít had a migraine since taking it,
however I have missed my period this month. I am currently 15 days late and have
had a negative pregnancy test today. I am wondering if it could have
affected my cycle in anyway or is it just a coincidence?
I have had one such report regarding menstrual changes or a shift in cycles. See below
Parkinson's disease, results not consistent
Neurol Sci. 2017. The efficacy and safety of coenzyme Q10 in Parkinson's disease: a meta-analysis of randomized controlled trials. The current meta-analysis provided evidence that CoQ10 was safe and well tolerated in participants with PD and no superior to placebo in terms of motor symptoms. According to these results, we cannot recommend CoQ10 for the routine treatment of PD right now.
A small but promising study found that it may help stop the nerve cell death that characterizes Parkinson's. disease. The study involved just 80 people. Half ate maple-nut flavored wafers containing various doses, half took a placebo for up to 16 months. By the study's end, the 23 patients on the highest daily doses had less decline in mental function, movement and ability to perform daily living tasks than the placebo group. Research has suggested that energy-supplying structures inside cells called mitochondria may be impaired in Parkinson's disease. Patients studied had early-stage Parkinson's and took a placebo or CoQ10 in doses of 300 milligrams, 600 mgs or 1,200 mgs daily. By the eighth month, the 23 patients on the highest dose showed significantly less impairment than the others. Side effects, including back pain, headaches and dizziness, were mostly mild.
Comments: I'm surprised these patients could tolerate these very high doses of CoQ10. I have had feedback from those using high doses that, in some people, there is excessive stimulant-like effect and high levels of alertness that may cause insomnia.
Pilot trial of high dosages of CoQ10 in patients with Parkinson's
Exp Neurol. 2004.
The safety and tolerability of high dosages of coenzyme Q10 were studied in 17 patients with Parkinson's disease in an open label study. The subjects received an escalating dosage -- 1200, 1800, 2400, and 3000 mg per day with a stable dosage of vitamin E 1200 IU/day. The plasma level reached a plateau at the 2400 mg/day dosage and did not increase further at the 3000 mg/day dosage. Our data suggest that in future studies of CoQ10 in Parkinson's disease, a dosage of 2400 mg/day (with vitamin E/alpha-tocopherol 1200 IU per day) is an appropriate highest dosage to be studied.
Antioxid Redox Signal. Jan 11 2014. Effects of high-dose coenzyme Q10 on biomarkers of oxidative damage and clinical outcomes in Parkinson disease. An open-label dose-escalation study was performed to examine the effects of CoQ10 on biomarkers of oxidative damage and clinical outcomes in 16 subjects with early idiopathic PD. Each dose (400mg/day, 800mg/day, 1200mg/day and 2400mg/day) was consumed daily for two weeks. High-dose CoQ10 was well-tolerated and improvements in total Unified Parkinson Disease Rating Scale (UPDRS) were observed following study completion. Plasma F2-isoprostanes (adjusted for arachidonate) were significantly reduced in the 400-1200 mg/day dose range but increased at 2400 mg/day dosage. A similar pattern of change was observed with serum phospholipase A2 activities. Levels of plasma all trans-retinol, plasma total tocopherol, serum uric acid and serum total cholesterol were unchanged despite an increase in CoQ10 dosage. Subjects with symptomatic benefits from CoQ10 had lower baseline plasma ubiquinol and decreased F2-isoprostanes per unit arachidonate. These results lead to the hypothesis that the therapeutic response to CoQ10 depends on baseline levels of ubiquinol and whether the dosage of CoQ10 used is capable to ameliorate the burden of oxidative damage.
JAMA Neurol. 2014. A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit.
Prader-Willi Syndrome treatment
My son was born in 2001 with Prader-Willi Syndrome. At the age of 3 months William was still sleeping 20 plus hours a day had no normal wake / sleep pattern when I ordered coq10 and began giving William 90 mg daily, he almost immediately responded with a normal wake / sleep pattern.
We have not evaluated this condition, however we will mention it on our website and maybe others may try it and give us feedback.
Supplementation reduces the risk of developing pre-eclampsia in women at risk for the condition.
Coenzyme Q10 supplementation during pregnancy reduces
the risk of pre-eclampsia.
Int J Gynaecol Obstet. 2009.
Women at increased risk of pre-eclampsia were enrolled in a randomized, double-blind, placebo-controlled trial. Women were assigned to receive 200 mg of CoQ10 or placebo daily from 20 weeks of pregnancy until delivery. Thirty women (25%) in the placebo group developed pre-eclampsia compared with 14% in the treatment group.
The effect from 30 mg is mild, mostly consisting of a slightly higher energy level. The effects become more noticeable with 50 mg. I have taken up to 100 mg in the morning. On this dose, I notice an increase in energy as the day goes on, with an urge to take a long walk or be physically active. There is enhanced focus, motivation, and productivity, along with the desire to talk to people. The 100-mg dose, though, is too much since I feel too energetic and alert even in late evening when I want to slow down and get ready for sleep. I usually do not recommend more than 10 to 50 mg on a long term basis without medical supervision.
How does it work?
Each cell in the body needs a source of energy to survive, so cells break down sugars, fats, and amino acids to make energy. Small enclosures within cells that make this energy are called mitochondria. CoQ10 exists naturally in our mitochondria and carries electrons involved in energy metabolism. CoQ10 is essential in the production of adenosine triphosphate (ATP), the basic energy molecule of each cell.
In the bloodstream, CoQ10 is mainly transported by lipoproteins such as LDL (low-density lipoprotein) and HDL (high-density lipoprotein). It is thought that CoQ10 is one of the first antioxidants to be depleted when LDL is subjected to oxidation. Hence, it is an important nutrient that prevents the oxidation of lipoproteins, thus potentially reducing the risk of arteries from forming plaques and getting damaged. In healthy individuals, it is found in high concentrations in the heart, kidneys, and liver.
Serum coenzyme Q10 concentrations in healthy men supplemented with 30 mg or 100 mg coQ10 for two months in a randomized controlled study.
Serum CoQ10 concentrations were evaluated in healthy male volunteers supplemented with 30 mg or 100 mg CoQ10 or placebo as a single daily dose for two months. Median baseline serum CoQ10 concentration in 99 men was 1.2 mg/l. Supplementation with 30 mg or 100 mg resulted in median increases in serum concentration of 0.55 mg/l and 1.3 mg/l, respectively, compared with a median decrease of 0.2 mg/l with placebo. The change in serum CoQ10 concentration did not depend on baseline serum CoQ10 concentration, age, or body weight.
Is CoQ10 available in liquid form? Does it offer any additional benefit in
liquid as opposed to capsules or softgels?
Yes, some companies do sell it in liquid form. I don't see any reason to take CoQ10 liquid unless a person has difficulty swallowing pills. Plus, the liquid form is more expensive and could be less stable in terms of storage.
Does the effectiveness matter if it is taken in
capsule form or if emulsified in an oil like alpha tocopherol. I read an advertising
leaflet that said not to waste money on CoQ10 tablets or capsules, because they cannot be
absorbed into blood stream.
There are probably differences in absorption between different CoQ10 products, and perhaps oil emulsified products are better absorbed, however, most supplements contain 30, 60 or 100 mg which are dosages far greater than normally needed by the body. Hence, even if 100 percent is not absorbed, practically speaking it should not make too much difference.
Iíve read conflicting articles regarding the amount of
CoQ10 absorbed from the intestines depending on its form.
Researchers at the Alfred Hospital and Baker Medical Research Institute, in Melbourne, Australia evaluated two different preparations: a soybean oil-based preparation and a complex micelle emulsion. Twelve healthy individuals received 300 mg daily of either preparation for 7 days in a double-blind cross-over design. Both preparations induced significant increases in serum levels and there was were no differences between CoQ10 levels for the two preparations at either time point. Since most people take a large dose of coQ10, such as 60 or 100 mg, even if one preparation were not absorbed as well, there should still be plenty to be helpful.
Prescription drug interactions
These include atorvastatin (Lipitor and Torvast), fluvastatin (Lescol), lovastatin (Mevacor, Altocor), pitavastatin (Livalo, Pitava), pravastatin (Pravachol, Lipostat), rosuvastatin (Crestor) and simvastatin (Zocor, Lipex).
Atorvastatin decreases the CoQ10 level in the blood of patients at risk for cardiovascular disease and stroke.
Arch Neurol. 2004.
Widespread inhibition of CoQ10 synthesis may explain the most commonly reported adverse effects of statins, especially exercise intolerance, myalgia, and myoglobinuria.
Histol Histopathol. 2014 Nov 4. Does coenzyme-Q have a protective effect against atorvastatin induced myopathy? CoQ10 may ameliorate atorvastatin induced skeletal muscle injury.
Warfarin - Coumadin blood thinner
The administration of CoQ10 and warfarin does not significantly affect the anticoagulant effect of warfarin in rats. A Human trial shows Co Q10 and Ginkgo biloba do not have a strong influence on the clinical effect of warfarin.
Side effects, safety, caution, danger,
High dosages of CoQ10, such as more than 100 or 200 mg, can induce restlessness, insomnia and fatigue. Long term side effects of high dose intake are not clear at this time. I usually do not recommend more than 20 to 60 mg daily on a long term basis without medical supervision or a good reason to take it.
Dr. Sahelian, thanks so much for your forthright, empirically oriented common sense approach to the information you provide. Your reviews and assessments of supplements are some of the most informative and useful of any available. I always read them before trying anything new. For example, I found your insights on the potential insomnia effects of Coq10 and tyrosine to perfectly align with my own experience; yet no one else seems to write about this, even recommending 300mg or more of Coq10 per day. If I took this I wouldnít sleep for days.
I have found your web site very helpful. It seems to
provide a very realistic approach to vitamins and supplements. I must be very
sensitive because I had terrible insomnia on daily 30 mg doses. It was
only through your web site that I finally figured out that correlation.
Most of the time it takes 60 to 100 mg or more to cause the insomnia side effect, but some people are much more sensitive than others.
I am male, 52 year old from India with mild CHF and
hypertension. After several trials of medications I started feeling better with a
combination of lisinopril and atenolol and an addition of an Ayurvedic compound. Soon I started feeling better and
even started exercising on my Bullworker. It so happened that I read about CoQ10
in a pharmacy ad here and started
taking initially 30 mg and then went up to 100 mg. For the first couple of
days I felt better, soon I felt quite sick, by BP seemed to increase, my heart
seemed to pound and my heart rate seemed to increase. Since none of such
side-effects is documented on the internet I continued to take them and
continued to feel sick. Soon I reduced the dosage to only 30 mg. Yesterday
night I took one 100 mg capsule and again right from today morning I have
started feeling sick with increased hypertension, a feeling of heart pounding
etc. I read your article on your site that
it had a very energizing effect on you. On the contrary, any dose above 30
mg makes me extremely drowsy.
Different people have different reactions to medications and supplements, and much depends on dosage and interaction with other medications. Perhaps 100 mg is too high a dose for you or it is interacting with the lisinopril and/or atenolol. Some people may do better with a dosage of 10 mg to 30 mg daily or every other day.
I am a medical doctor and have been taking 100mg for several years--originally for GI dysmotility (Hollow Visceral Neuropathy) and have not yet noticed any untoward reactions.
My doctor told me to take 100mg every day, and I am feeling
worse than ever: tired, no get up and go, difficulty concentrating, waking up
more tired than when I got to bed, falling asleep during the day, you name it.
Too high a dose can cause insomnia or shallow sleep resulting in tiredness the next day.
I recently began taking COQ10 and noticed that there was a significant change in my health. I've felt so much better physically and mentally. My ability to focus had been lacking in the past year or so but now I think clearer. My energy levels are higher.
I am a nurse and well acquainted with traditional medicine. I was diagnosed with breast cancer. My younger sister was diagnosed several years ago. Our cancers were IDC and strongly ER and PR positive. Her cancer involved lymph nodes, mine non nodal. She went through chemo and radiation treatments, tried anti-hormonal (but too many adverse side effects). I have just finished radiation and will be encouraged to take tamoxifen. I started using "natural" progesterone cream when my sister was diagnosed after reading Dr John R. Lee's book on progesterone and his comment on his breast cancer patients maintaining remission while using the cream, my sister started at this time as well, I used the cream in hopes of deterring breast cancer and estrogen dominance...she used it to deter a breast cancer recurrence. My sister used many other supplements as well, has taken 100mg CoQ10 and other supplements. When my excisional biopsy lumpectomy came back positive with unclear margins, I asked my sister about her supplements and she mentioned the CoQ10, so I googled it and found about Dr. Folkers study in Denmark, using 390 mg and other supplements. I increased daily until I reached a 400 mg dose. MRI with CAD determined no other noticeable breast cancer, so partial mastectomy was scheduled for 3 weeks later to get clear margins and sentinel node biopsy. Well I took 400mg all the way until the night before surgery. The fairly large resected area came back with only a single 2.5mm cribiform cancer and at least a 5mm clear margin from there, initially the surgeon told me the first path report the cancer went to the edge of the margins, so to only find a single area on the whole resection made me think the supplement may have helped clear things up, Just as the women in the Denmark study experienced.
In 1990 our subsidiary company Hawthorne Products (we make natural medications for horses there) and Washington State University did a six week study on CO Q 10 with 10 horses, five on a placebo and five on 250 mg per day. We were trying to determine if the Co Q 10 would help prevent the "tying up syndrome" in racehorses. After five weeks Dr Ratzlaff called and said they have not seen any difference in the horses. I then asked if they could do a test in the sixth week for blood oxygen. He said yes, but only on the venus blood not arterial side, as some of the horses were borrowed for the study and didn't want to take a chance. At the end of the sixth week Dr Ratzlaff called and said that all five horses on the Co Q 10 had 30% more blood oxygen in the venus blood than the placebo horses ! He then told me how important blood oxygen is to the blood cells and how cancer starts in our body in places with little or no blood oxygen. He asked me how did I know what they would find and I told him it was just a hunch and here is what lead me to asking for that blood oxygen test.My wife had gone to the ER with a chest pain and while there they took her blood sample and then came back and took it again with a puzzlement. My wife was a smoker for 30 years, and a professional bowler. ( She was a national and CA state champion) The ER told her that her blood oxygen was that of a sixteen year old ! (a smoker will not get those results). Some months later she went for an eye examination and the Dr said that she had very good blood oxygen in her blue eyes. That was what lead me to ask the vets.To my knowledge, and I have stacks of studies on CO Q 10 dating back to MERCK labs discovery of Co Q 10, I have never seen any information about increasing the blood oxygen in humans. But I will be 80 years old in August, my health is very good and I have been taking 100 to sometimes 200 mg daily of Co-Q-10 for nearly 40 years along with other supplements. I don't feel that 30 -50 mg may be enough for older adults as we lose more as we age.(In passing, we here at Thoro'Bred make shoes for racehorses and have done so since 1949. Our shoes have been on the legends of racing, Secretariat, John Henry, Affirmed and Alesheba (triple crown winners) to todays top mpney winning horses, California Chrome, American Pharoah and Arrogate.)Sincerely, Ed Kinney, President, Thoro'Bred Inc.