This edition: Supplements for eye health and prescribed use of aspirin
Question: My new optometrist has advised me to start taking several supplements for eye health: Lutein, Zeaxanthin, Omega-3, Vitamin C, Vitamin E, Zinc, Vitamin D, Vitamin B-12, and a Probiotic. My old eye doctor (an MD) had never given me any cause for concern regarding my vision or the health of my eyes, particularly in her inspection of my retina. I’m wondering about the necessity and effectiveness of starting to take all these supplements. Do you have any advice?
Answer: Some of those supplements (not all) have been found to help patients who have macular degeneration. The two biggest studies were AREDS and AREDS2. I covered them on the Science-Based Medicine blog at
A Cochrane review found that the positive evidence was mainly from one large trial, while there were several smaller trials that showed no benefit.
The original AREDS trial showed that a combination of vitamin C, vitamin E, vitamin A, zinc, and copper slowed the progression of vision loss in patients with moderate to severe macular degeneration. It did not help those with milder disease, and there has never been any evidence that supplements do anything to prevent macular degeneration from developing in the first place. The second trial only compared the original formula to a revised formula. It omitted the vitamin A (because it can be harmful to health), and added lutein, zeaxanthin, and omega-3s.
In short, the advice you were given is not standard advice and is not evidence-based. The ONLY reason to take supplements for eye health is if you have been diagnosed with moderate to advanced macular degeneration, and even then the evidence is not very strong. Some providers believe antioxidant supplements might be valuable for various health problems and choose to recommend them before the evidence is in. I don’t think that is wise.
You might want to discuss the evidence with your optometrist; or you might want to look for a different optometrist who is not overly enthusiastic about the potential benefits of untested supplements.
Answer: The idea behind aspirin is that it is an anti-platelet drug. A major cause of heart attacks and strokes is when platelets glom together to form a clot around a damaged cholesterol plaque in an artery. The clot can block the artery where it formed, or it can embolize (break off and lodge in a smaller artery downstream). Aspirin reduces the tendency to form clots. Also, aspirin has an anti-inflammatory effect that probably helps reduce the formation of plaques to some extent.
The problem is that when you reduce the ability of the blood to clot, you bleed more easily; you are more likely to have a life-threatening brain hemorrhage or bleeding from the GI tract. That’s why a low dose is recommended: usually 81 mg a day, or one baby aspirin, rather than a whole standard aspirin tablet of 325 mg. Research has confirmed that aspirin reduces the incidence of heart attacks and strokes, but it also increases the risk of serious bleeding events. There is a fine line between benefits and risks, so it is not for everyone.
It is pretty well established that aspirin is effective for secondary prevention, preventing a second event in patients who have already had a heart attack or stroke. There is still uncertainty about its use in primary prevention in healthy people to prevent a first cardiovascular event. Steven Novella recently covered this issue on the Science-Based Medicine blog at http://www.sciencebasedmedicine.org/low-dow-aspirin-for-primary-prevention/#more-34528
A recent study in Japan was reported in the media as showing primary prevention didn’t work, but as usual the media missed important details. 14,464 high-risk Japanese patients over age 60 were randomized to take 100 mg of aspirin a day or no aspirin. The study was terminated early because there was no significant reduction in a composite measurement of death, non-fatal stroke, and non-fatal heart attack. But the study did show a significant reduction in non-fatal heart attacks and transient ischemic attacks (TIAs). Unfortunately it also showed a significant increase in hemorrhages requiring transfusion or hospitalization.
It’s hard to draw firm conclusions from that study. It was not placebo-controlled. A tenth of patients were lost to follow-up. By the end of the study, only 76% of patients were compliant in taking the aspirin and over 10% of patients in the no-aspirin group had started taking prohibited anti-platelet medications. Patients in the aspirin group knew they were getting aspirin, so they may have been more likely to report complications. Aspirin may also reduce the risk of colon cancer and other cancers, which could have affected the death rate. And the results may not be applicable to the typical American patient, since the Japanese have different base rates of cardiovascular disease, different diets, and different rates of obesity and other risk factors.
The bottom line is that aspirin works, but not everyone should take it. The evidence for secondary prevention is strong. The benefit for primary prevention is small: according to one analysis 1667 patients have to be treated to prevent one heart attack or stroke. So individual decisions about aspirin should take everything into account, including the individual’s overall risk of a heart attack or stroke, any factors that could influence their risk of bleeding complications, and their willingness to accept a small risk for a small benefit.
Harriet A. Hall is a retired family physician, former U.S. Air Force flight surgeon, and health advocate who writes about alternative medicine and quackery for Skeptic magazine, Skeptical Inquirer and Science-based Medicine.