How do antioxidants prevent chronic diseases such as cancer, heart disease, and macular degeneration?

Maybe. For macular degeneration - free radicals appear to play a significant role. There is currently a prevention arm of the areds which is looking at supplements in preventing the progression of macular degeneration. It's often better to eat a good diet, exercise and reduce other risk factors than take supplements. Oh yes, please don't smoke!
Oxidative stress. We know oxidative stress can cause changes in cells and become cancerous. So logic would say, antioxidants would prevent cancer. But unfortunately studies to this day have yet to prove antioxidants do anything to prevent cancer. This needs to be investigated further.

Related Questions

What are the means by which antioxidants prevent of chronic diseases such as cancer, heart disease, and macular degeneration?

Do they? Re: cancer -- pre-clinical evidence supported supplements such as anti-oxidants as "chemo-preventive" interventions to decrease the risk of cancer. However, the test tube (in vitro) predictions did not work in humans (in vivo) in a number of studies including vit e, beta carotene in lung cancer, various supplements in head/neck cancer & selenium in lung/prostate. Humans are complicated.
They don't. There's a whole lot of conspiracy-mongering going around these days that somehow the pharmaceutical and health care industries are suppressing some "magic bullets" that can prevent all of these diseases. If this were true, I don't know a doctor who wouldn't immediately shout it from the roof-top and get all of their patients on the stuff.

Antioxidants prevent chronic diseases like heart disease?

We thought so. So we knew that oxidative stress is a key factor in cancers and other disease processes. So naturally we thought, lets load patients with antioxidants to prevent that. We did studies and it showed antioxidants have no effect. Which means there's a lot more to it than the oxidation issue. So although logic says antioxidants are good, we just don't have definitive proof of it.

Is dietary fat advice for cancer prevention similar to heart disease prevention?

Pretty much. The link isn't direct in either case, so "eat healthy" is the general advice. Shoot for the "mediterranean diet" or an Asian menu and you'll be fine.

Dietary fat advice for cancer prevention is similar to heart disease prevention. So why don't people follow it?

Fat tastes good. It's hard to eliminate fat from your diet, we are all hard wired to like the taste of it. Mmmmmm...Donuts.
Habit. Habits sometimes can be hard to break and hard to establish. This is why it is important to establish healthy habits early in life. One of the best things we can do for young people is to set a good example, so they can have life-long healthy habits.
Denial. Many people don't think they will be the one to get cancer even though 1 out of 2 men do, as do 1 out of 3 women. Patients are also confused if they can even prevent cancer and if there is a definitive link between cancer and diet. No study has ever shown an absolute connection. Even though smoking can cause lung cancer, not every smokers gets it. Therefore, people stay in denial about the risks.

Just watched "forks over knives." will going vegan prevent heart disease, stroke, cancer, etc? Sounds too good to be true -- is it accurate?

Too good to be true. Many illnesses mentioned may be helped but not prevented with a vegan diet. Genetics and environmental issues may also play roles in the development of many illnesses. Living an active life, exercising regularly, controlling your weight and having a healthy family history will pay more dividends than simply pursuing a vegan diet.
Probably true. This documentary does have its own agenda as well but most studies suggest that a healthier, balanced diet is likely to reduce the risks of cancer, stroke, heart attack, etc. If you properly watch your diet (even without being a vegan), you will likely reduce your health risks. Alternatively, there are vegans who over-eat and hence suffer from obesity (although rare). Consult your pcp please.

My paternal family has history of cancer & heart disease, from both sides. What can I do best to prevent? I'm very similar to my father physically

Prevention. Learn what specific type of cancers your family runs and what heart disease (s). Check on line for what specific steps you can take regarding diet, exercise and perhaps other steps. In general exercising regularly, not smoking, mediterranean diet are all good basic steps.

My good cholesterol is 94, will this high number prevent other diseases such as cancer or heart disease?

It helps. Having a high HDL is good, and is a positive factor in the risk calculations that doctors use to guide them in choosing the appropriate therapeutic recommendations for you. However, a high HDL by itself will not prevent cancer or heart disease.

How do antioxidants promote prevention of macular degeneration?

Yes. There are several commercially available vitamins that reduce progression of macular degeneration. Ocuvites and I caps make a number of different supplements. Healthy eating of course is best incorporating spinach, kale, fish, and other green leafy vegetables into your diet.
Not great. Doesn't work well for primary prevention. May help if already have disease in one eye and want to prevent worsening in the fellow eye. Antioxidants block damaging free radicals.
Yes. The vitamin formula that was shown to slow the disease is areds. Consumption of fish (tuna or salmon) has been shown to reduce the risk by up to 40% in women.
They don't. There's no study, as far as I know that shows antioxidants prevent macular degen. There are studies that show that if you do have the disease, certain vitamins do help slow the progression.