Oxidative stress is the imbalance between the body's production of free radicals and their neutralization by antioxidants. Oxidative stress can lead to problems in the body, including organ and tissue damage.
Free radicals are harmful compounds produced by biological processes in the body, such as digesting food, breathing, turning fats into energy, and metabolizing alcohol and drugs.
Free radicals can cause problems within the body, including blocking the action of major enzymes, destroying cell membranes, preventing cellular processes the body needs to function properly, preventing normal cell division, blocking energy generation, and destroying DNA. They can also promote inflammation.
Antioxidants neutralize free radicals and help minimize the damage they cause.
This article will discuss why oxidative stress and free radicals matter, the symptoms and long-term effects of oxidative stress, what raises oxidative stress, how to lower oxidative stress, and small changes that can make a big impact on oxidative stress.
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Table of Contents
Oxidative Stress and Free Radicals: Why Do They Matter?
Free radicals are unstable molecules created when oxygen is metabolized in the body. They vary in shape, size, and chemical configuration.
Free radicals "steal" electrons from other molecules. This changes the other molecules' structure or function, causing damage such as altering instructions coded in DNA, changing a cell's membrane (affecting the flow of what enters and leaves the cell), and other effects.
At low or moderate levels, free radicals can play beneficial, even vital, roles within the body. In the right amount, they are crucial to maintaining human health.
Antioxidants help keep free radicals in check by neutralizing them. When there is an imbalance between the free radicals being produced and their elimination by antioxidants, oxidative stress occurs.
Oxidative stress can harm cellular structures such as:
- Membranes
- Lipids
- Proteins
- Lipoproteins
- DNA
If not controlled, oxidative stress can be associated with:
- Chronic and degenerative medical conditions
- Speeding up the body's aging process
- Acute medical problems (such as stroke)
What Are Antioxidants?
Antioxidants are molecules that neutralize free radicals by giving them electrons. They also help repair DNA and maintain the health of cells.
Hundreds to thousands of substances work as antioxidants. They aren't interchangeable. They have a different makeup, perform different roles, and are believed to work as parts of a network.
Certain foods contain antioxidants. Nutrient antioxidants include vitamins A, C, and E and copper, zinc, and selenium minerals. Non-nutrient antioxidants include other dietary food compounds, such as phytochemicals found in plants like tomatoes and cranberries.
Antioxidants may be water-soluble. These are best absorbed by the body but are rapidly eliminated through urine. Polyphenols and vitamin C are examples of water-soluble antioxidants.
Antioxidants can also be fat-soluble. Fats must be present for the body to absorb and use these antioxidants. Because they are not easily removed from the body, they can accumulate to levels that are too high. Vitamin E is one fat-soluble antioxidant.
Oxidative Stress Symptoms and Long-Term Effects
Oxidative stress contributes to cellular damage. Over time, this can play a role in the development of a wide range of medical conditions, some of which include:
- Chronic obstructive pulmonary disease (COPD)
- Atherosclerosis (thickening or hardening of the arteries due to a build-up of plaque)
- Alzheimer's disease
- Heart disease (free radicals prompt low-density lipoprotein, or LDL, cholesterol to stick to artery walls)
- Liver disease
- Certain cancers (such as oral, esophageal, stomach, and bowel cancers)
- Arthritis
- Vision loss (from deterioration of the eye lens)
- Parkinson's disease (and other conditions arising from damage to nerve cells in the brain)
- Accelerating the aging process
- Potentially neuropsychiatric disorders such as anxiety and depression (more research is needed)
Conditions Associated With Higher Oxidative Stress
Research has found links (of varying degrees) between oxidative stress and the onset and/or progression of a variety of medical conditions, including:
- Cardiovascular diseases (atherosclerosis, ischemia, hypertension, cardiomyopathy, cardiac hypertrophy, and congestive heart failure)
- Pulmonary diseases (like asthma and COPD)
- Neurocognitive/neurological disorders (such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), depression, and memory loss)
- Metabolic disorders (like diabetes)
- Certain cancers
- Rheumatoid arthritis
- Problems with kidney function
What Raises Oxidative Stress?
Oxidative stress can arise when there are more free radicals than the body can neutralize. Free radicals can be generated from endogenous (originating in the body) sources and exogenous (originating outside the body) sources.
Endogenous free radical production can stem from sources such as:
- Immune cell activation
- Inflammation
- Infection
- Cancer
- Ischemia (restricted blood flow/oxygen to a part of the body)
- Excessive exercise
- Mental stress
- Aging
Exogenous free radical production can result from sources such as:
- Environmental pollutants
- Heavy metals
- Certain medications (such as cyclosporine, tacrolimus, gentamicin, and bleomycin)
- Certain products from cooking (such as used oil, excessive consumption of polyunsaturated fatty acids, food additives, and smoked meat)
- Tobacco smoke
- Alcohol
- Exposure to radiation (including ultraviolet, or UV, radiation/sunlight)
- Pesticides and other chemicals
- Ozone
- Allergens
How to Lower Oxidative Stress
Eating a diet rich in antioxidants can help prevent or reduce damage caused by oxidation and reduce the risk of several conditions, such as heart disease and certain cancers.
Antioxidants can be found in fruits, vegetables, whole grains, nuts, and some meats, fish, and poultry.
Good sources of antioxidants include:
- Cruciferous vegetables: Like broccoli, cauliflower, and cabbage
- Leafy green vegetables: Like spinach
- Other vegetables: Like corn, tomatoes, carrots, eggplant, pumpkin, red capsicum, and sweet potatoes
- Alliums: Like leeks, onions, and garlic
- Fruits: Such as apricots, watermelon, pink grapefruit, mangoes, grapes, berries, citrus fruits, apples, oranges, black currants, kiwi, and avocado
- Legumes: Like soybeans, tofu, lentils, and peas
- Nuts and seeds: Such as sesame
- Herbs: Like parsley
- Whole grains: Such as bran
- Tea: Including green tea
- Vegetable oils: Like wheatgerm oil
- Milk
- Seafood
- Lean meat
These foods offer many different types of antioxidants, and eating a variety of them is important. Research suggests antioxidants work best when combined with other nutrients, plant chemicals, and other antioxidants.
Increasing evidence suggests antioxidants are more effective when consumed as part of whole foods rather than when isolated from a food or as a supplement.
Consuming antioxidant vitamins or minerals at significantly higher levels than the recommended dietary amounts can prompt them to act as pro-oxidants and cause damage. Talk to a healthcare provider or registered dietitian before taking supplements.
Eating foods rich in antioxidants is part of a healthful lifestyle plan, but they are not a substitute for overall healthy lifestyle choices.
Small Changes That Make a Big Impact on Oxidative Stress
Preventing oxidative stress is all about balance. More doesn't always mean better, especially when it comes to supplements. Focus on overall balanced lifestyle choices, like:
- Eat a balanced diet with a variety of nutrient-rich foods, including those that are sources of antioxidants.
- Talk to a registered dietitian about developing a healthful eating plan that works for you.
- Get plenty of exercise without overdoing it.
- Don't smoke.
Summary
Free radicals can cause damage within the body. Antioxidants neutralize free radicals and help prevent or minimize the damage from them. Oxidative stress is when there is an imbalance between the production of free radicals and the body's ability to neutralize them.
Oxidative stress is linked to several health conditions, such as cardiovascular disease, pulmonary disease, and neurological conditions.
Free radicals can be created from processes within the body or exposure to factors outside the body, such as pollution, cigarette smoke, and UV radiation.
Antioxidants can be found in many foods, particularly fruits, vegetables, whole grains, nuts, and some seafood, meats, and poultry. Research suggests antioxidants are more effective when they come as part of a variety of whole foods rather than in isolation or as a supplement.
Preventing oxidative stress is more about balance than consuming large amounts of antioxidants. Aim for a balanced diet with a variety of nutrient-rich foods, and practice other healthful lifestyle habits.
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