Are antioxidants good for you? The short answer is yes, but buyer beware. Just because something is good for you doesn’t mean you should start taking a giant mega-dose of it. Antioxidants are great when the come from natural sources as a part of a healthy diet. But like everything else, a closer look at their physiological action explains why you can get too much of a good thing.

It’s All About The ROS

What are antioxidants? To answer that question, you have to understand reactive oxygen species, or ROS. And to do that, you have to understand how your cells produce energy. So here we go: a very quick overview of cellular energy metabolism.

In human cells, like other eukaryotes (everybody but the bacteria), energy is made in a specialized cellular structures called mitochondria. Mitochondria are these strange, double-membraned organelles that are highly specialized – they contain their own DNA, make their own proteins, and are tightly regulated by the cell. Essentially, mitochondria are energy powerhouses, or the cell’s equivalent of a power plant. Below is a 3D view of the structure (thanks to T. G. Frey of San Diego State University):

watch : http://www.sci.sdsu.edu/TFrey/?MitoMovies/CrisMitoER.mov

Using a complex process, mitochondria take our fats, carbohydrates, and excess proteins and turn them into a four-carbon molecule called Acetyl CoA. This molecule goes through a series of reactions in what is called the Kreb’s Cycle which results in the creation of high-energy electrons taken from the bonds.

These electrons are then passed down a chain of enzymes which use the energy they possess to create a proton (H⁺) gradient between the center of the mitochondria and the between-membrane space, eventually reducing oxygen into water (O₂ –> H₂O).

It’s this proton gradient that is used to drive an enzyme called ATP synthase, which creates ATP, the functional energy molecule used by our cells.

But the system isn’t perfect. Every once in awhile, instead of making harmless water, the chain makes unstable oxygen molecules, which are referred to as free radicals. These molecules are dangerous to the cell because they are highly reactive – in other words, they attack chemical bonds – hence their other name, reactive oxygen species (ROS). They can cause damage to DNA, enzymes, proteins and many of the other vital components of a healthy cell.

Luckily, our bodies have innate mechanisms to deal with ROS, like the enzyme catalase which converts hydrogen peroxide (a kind of ROS) into water and oxygen. But as we age, our mitochondria get less and less efficient, producing more and more ROS. If too many ROS are produced and they overwhelm our innate damage repair mechanisms, our cells suffer, and either become non-functional or even cancerous.

That’s where antioxidants come in. Antioxidants are compounds which react with free radicals and neutralize them, thus protecting our bodies from oxidative damage by ROS. They vary widely and are found in all kinds of foods we eat every day. Perhaps the most famous antioxidant foods are the colored berries like blueberries and raspberries, which are chock full of a antioxidants like Vitamin C and Vitamin E.

So ROS are bad?

Well… like everything else, it’s not quite that simple. Yes, reactive oxygen species can be very damaging. Some scientists finger them as the direct cause of aging, and because of the damage they can cause, they are thought to play a pivotal role in many diseases from Alzheimer’s to cancer. ROS production is increased in people who are overweight or obese, and is considered one of the reasons why weight gain is so damaging to the body.

But many ignore the fact that ROS are a normal and regular part of cell metabolism. Even when we’re healthy, we boost the production of ROS when we exercise and when we eat. As it turns out, we need them. They are important in a number of cellular pathways, including those related to programmed cell death (apoptosis), as they are a direct measure of how much energy is being created by a cell at a given time. Increases in ROS may actually be beneficial at the right times.

For example, one study found that if you up the ROS in mice being fed a high fat diet, you actually prevent them from becoming insulin resistant. Insulin resistance is the first step towards diabetes – it occurs when our bodies stop responding effectively to the insulin we release to store glucose uptake.

Over time, eating too much (especially too much sugar) leads to a constantly high insulin levels, and our bodies simply become less sensitive to insulin. ROS, as the researchers explain, are key in insulin signaling, and without them, our cells can’t respond efficiently to insulin.

“In the case of early type 2 diabetes and the development of insulin resistance, our studies suggest that antioxidants would be bad for you,” explains Tony Tiganis of Monash University in Australia.

Furthermore, increases in ROS are pivotal in the heart’s ability to prevent damage during a heart attack. If you boost ROS signals before a heart attack, it allows the cells to precondition and prevents later damage from oxygen deprivation. This pathway, including ROS, are being evaluated as targets for therapeutics and pharmaceuticals to reduce or prevent heart damage.

As with anything, ROS are healthy for you when they’re kept balanced by the body’s defensive enzymes and antioxidants. Natural, low-ish levels of ROS signaling, like that produced when you eat a good diet and exercise, is good for you. But get too much of a good thing – like when your body’s natural oxidation defenses break down – and it becomes a bad thing. Eating a variety of fruits and vegetables, packed with antioxidants, has been shown to improve the body’s ability to deal with ROS properly, improving all kinds of physiological parameters and aiding in the prevention or treatment of a wide variety of diseases.

Should I take extra antioxidants?

Increases in overall fruit and vegetable intake have shown to be great for our bodies, but this is likely due to the interplay between many different compounds. The jury is still out on whether supplementing your diet with specific antioxidants improves your health.

Clinical trials have had remarkable trouble finding actual benefits from supplementing diets with individual or even combined antioxidants. A vegetable or fruit is better for you because doesn’t just contain one or two antioxidants; it also contains a balance of vitamins, minerals and enzymes that are impossible to reproduce in pill form.

And more importantly, you can over do it. The line between healthy and unhealthy blurs when it comes to dietary supplementation with excessive amounts of antioxidants. For example, you smokers out there might want to watch your beta-carotene intake. Beta-carotene is an antioxidant, found in many vegetables including kale and spinach, and researchers had hoped that supplementing the diets of smokers with it and another antioxidant, retinol, would help prevent lung cancer.

But the reverse occurred – beta-carotene was found to actually increase the risk of lung cancer and death when taken as a supplement by those who were at high risk for the disease. Why it had this strong, negative effect is not fully understood, but it serves as a warning that over-supplementing isn’t a good idea.

Similarly, a meta-analysis of clinical trials involving Vitamin E found that high doses – >400 IU a day – increased risk of mortality. It’s likely that in both these cases, the excessive levels of antioxidants actually prevented the ROS from doing their job as signaling molecules, screwing up cellular signaling pathways including those that lead to cell death. Cells that don’t die when they should are at high risk for becoming cancerous.

You probably aren’t going to do yourself any damage by eating all the antioxidants you want – and, more likely, you’ll improve your diet. But don’t try and overdo it with pills. Cramming ten extra Vitamin C tablets isn’t going to do you any good. Antioxidants are better when they come straight from the source, as they exist in a form your body is prepared to use.

Studies have shown supplements simply don’t cut it, and super pills don’t replace eating a healthy, balanced diet with at least five servings of fruits and veggies a day. And in some cases, antioxidant supplements increase the risk of cancers, like beta-carotene did for smokers, and can be particularly damaging for those already on certain drugs.

If you really insist on taking supplement pills, be sure to talk to your doctor first and make sure what you’re taking is actually good for you and isn’t going to conflict with other medications. So-called nutritional supplements often tout amazing health benefits without any actual science to back them up.

Previous posts in the Understanding Our Bodies series:

• Leptin: The Fullness Hormone
• Serotonin: The Connection Between Food and Mood
• Amino Acids are Important!
• Dopamine and It’s Rewards

References:

1. Stadtman, E. (1992). Protein oxidation and aging Science, 257 (5074), 1220-1224 DOI: 10.1126/science.1355616
2. Liu, J. (2002). Memory loss in old rats is associated with brain mitochondrial decay and RNA/DNA oxidation: Partial reversal by feeding acetyl-L-carnitine and/or R-alpha -lipoic acid Proceedings of the National Academy of Sciences, 99 (4), 2356-2361 DOI: 10.1073/pnas.261709299
3. Zhang JW, Rubio V, Zheng S, & Shi ZZ (2009). Knockdown of OLA1, a regulator of oxidative stress response, inhibits motility and invasion of breast cancer cells. Journal of Zhejiang University. Science. B, 10 (11), 796-804 PMID: 19882753
4. Rhee SG (2006). Cell signaling. H2O2, a necessary evil for cell signaling. Science (New York, N.Y.), 312 (5782), 1882-3 PMID: 16809515
5. Loh, K., Deng, H., Fukushima, A., Cai, X., Boivin, B., Galic, S., Bruce, C., Shields, B., Skiba, B., & Ooms, L. (2009). Reactive Oxygen Species Enhance Insulin Sensitivity Cell Metabolism, 10 (4), 260-272 DOI: 10.1016/j.cmet.2009.08.009
6. Vanden Hoek T, Becker LB, Shao ZH, Li CQ, & Schumacker PT (2000). Preconditioning in cardiomyocytes protects by attenuating oxidant stress at reperfusion. Circulation research, 86 (5), 541-8 PMID: 10720416
7. Valko M, Leibfritz D, Moncol J, Cronin MT, Mazur M, & Telser J (2007). Free radicals and antioxidants in normal physiological functions and human disease. The international journal of biochemistry & cell biology, 39 (1), 44-84 PMID: 16978905
8. Wallig MA, Heinz-Taheny KM, Epps DL, & Gossman T (2005). Synergy among phytochemicals within crucifers: does it translate into chemoprotection? The Journal of nutrition, 135 (12 Suppl) PMID: 16317157
9. Goodman GE, Thornquist MD, Balmes J, Cullen MR, Meyskens FL Jr, Omenn GS, Valanis B, & Williams JH Jr (2004). The Beta-Carotene and Retinol Efficacy Trial: incidence of lung cancer and cardiovascular disease mortality during 6-year follow-up after stopping beta-carotene and retinol supplements. Journal of the National Cancer Institute, 96 (23), 1743-50 PMID: 15572756
10. Miller ER 3rd, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, & Guallar E (2005). Meta-analysis: high-dosage vitamin E supplementation may increase all-cause mortality. Annals of internal medicine, 142 (1), 37-46 PMID: 15537682
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You’ve probably heard people say that fish is better for you than any of the red meats.  Fish are chocked full of beneficial omega-3 fatty acids, and are considered to be highly nutritious by the National Institutes of Health, the American Heart Association, and the US Department of Agriculture (in a roundabout way) – which include fish in their recommendations for healthy eating.

But above and beyond their normal health benefits, researchers have found another reason to eat seafood – it might just boost your intellect.  At least that’s the claim of some fresh-caught research from Sweden, which found that a fish-laden diet improved the cognitive performance of teenage boys even when a whole slew of other variables were taken into account.  They suggest that something in fish has a strong, positive impact on intelligence – which might just explain why fish-heavy cultures like those in Asia and the Mediterranean seem to do so much better on IQ tests.

The Research

Researchers in Sweden studied how diet affected intelligence scores of teenage boys. They followed the dietary intake of fish in boys from age 15 until age 18, when they take their Swedish Military Conscription mental tests. The boys who ate fish at least once a week scored at least 7% higher than those that didn’t.  Eating fish more than twice a week boosted them up almost 12%.

The researchers didn’t just look at fish consumption. They compared a wide range of variables, including ethnicity, location, educational level, well being, and exercise and weight. But even with taking all these variables into account, it was clear that fish consumption had a significant positive association with improved cognitive performance. Regardless of their backgrounds or influences, simply eating fish made them perform better.

Watch this BBC Science short about another experiment relating to Omega-3 consumption and childhood intelligence performed in England – the results speak for themselves, literally. They won’t let us embed the movie unfortunately – just click on the picture below to view it:

What’s so great about fish?

The biggest benefit of fish is that they are a rich source of Omega-3 Fatty Acids, which are also common in tofu, nuts and soybean products.  Our diets generally lack Omega-3s.  Research has found that these unsaturated fats have positive effects on everything from heart rhythm to immune function. The U.S. Food and Drug Administration actually approved of a qualified health claim for dietary supplements of omega-3 fatty acids relating them to a reduced risk of heart disease – a stamp of approval not given to most supplements.  Continuing research suggests Omega-3s positively impact arthritis, asthma, lupus, kidney disease, cancer, and even depression.

Not only does fish have Omega-3s, it’s generally high in protein and low in fat.  A 3-ounce cooked serving of most fish and shellfish provides about 20 grams of protein, or about a third of the average daily recommended protein intake.  And not all protein is created equal – fish protein is top notch, containing an abundance of essential amino acids.  Seafood is a great alternative to beef, poultry and pork as a protein source because it tends to be lower in fat and is loaded with the essential meat minerals like iron, zinc and calcium. You can spare yourself even more bad fats and up the good ones by getting your filet grilled with lemon juice and olive oil.

Get Your Diet Swimming

Adding fish and seafood is an easy way to boost your health and your mental performance.  Instead of having the steak, try the grilled salmon instead.  Ideally, you should eat seafood twice a week or more as a source of protein. Think tuna sandwiches for lunch or a catfish filet for dinner.  The best benefits come from fresh fish, so get to know your local seafood markets.  Buying from fishermen supports the local economy and gets you the best prices on top-of-the-barrel health food.  And if you don’t live near the water, don’t panic – there are lots of great, frozen seafoods to choose from.

If you’re worried about sustainable seafood or environmental impacts, print out your regional Sustainable Seafood Guide from the Monterey Bay Aquarium. The yearly guides stay up to date on which fisheries are doing it right and which are destroying their stocks, so you can eat healthy and feel good about it. And, if you’re worried about quality, avoid the fish on the higher end of the food chain. Being on top might make them excellent to eat, but it also makes them more likely to contain environmental toxins like mercury picked up from eating other fish. A nice lowly catfish is environmentally sustainable and less likely to contain high concentrations of toxins.

If you just can’t stand the taste of fish, consider adding an Omega-3 supplement to your diet. While it’s not as good as the ‘reel’ deal, it’s at least a start.  But don’t give up on fish too quickly – there are a lot of varieties out there, and taste ranges.  There are lighter tastes like catfish and tilapia which might appeal to those who find salmon too fishy.  At least try a few different fish before you give up on liking ocean dwellers.  Supplements are rarely, if ever, a good substitute for simply eating healthy foods.  If you truly can’t stomach fish, try tofu or soy-rich products that also contain high levels of Omega-3s.

And for those of you like me who love seafood, research like this is just another excuse to go out and celebrate with a nice fillet.  Not only are you eating healthy, you might just be getting smarter for it.

Source:
Åberg, M., Åberg, N., Brisman, J., Sundberg, R., Winkvist, A., & Torén, K. (2009). Fish intake of Swedish male adolescents is a predictor of cognitive performance Acta Paediatrica, 98 (3), 555-560 DOI: 10.1111/j.1651-2227.2008.01103.x