Thoughts on superfoods (and antioxidants) – Part 1
BY CHRIS CHAN
What can be pretty annoying are things which are extravagantly marketed despite the fact that they cannot possibly match depicted expectations. One such item is a fad called “clean eating” – this irritates me because the term implies that if we do not embrace the foods faddists suggest, then somehow we would be eating dirty rubbish instead.
As someone who loves a good steak, this is a little objectionable, regardless of the millions of pulchritudinous Instagram pictures of “clean eating food” – especially as there is often little correlation between pretty-looking and good, tasty food.
Also, although I can be fond of salads, I just do not want the salads that “clean eaters” want to foist on people – my salads tend to have lashings of vinaigrette, crispy bacon, eggs, tinned sweet corn, greens, cheeses and whatever tastes good.
And it is not because I do not understand nutrition – there really can be a sensible approach to nutrition as opposed to regimented, restrictive and opinionated rules which are required to be followed like extremist religious sects.
Another such annoying item is something called “superfoods”. Please note this is not a medical classification – at best, superfoods can charitably be called a marketing ploy to convince people to consume certain items over other foods which are not so “super”.
This is not to say that real foods labelled as superfoods are not nutritious. In fact, many of the so-called superfoods (mainly vegetables and fruits) are actually quite interesting from a nutritional point of view and one definition of superfood is “a nutrient-rich food considered beneficial for health” – and normally includes “superfood supplements”.
However, in my opinion, there is actually no such thing as a superfood – practically any food can be classed as a “superfood” if ingested in the right context.
For example, the body of a person on the edge of starvation would be rather more grateful for the nutrients (and calories) in a bucket of deep-fried chicken than the minerals in a cup of green tea.
Talking of green tea, this has been hyped for years as one of the original superfoods – so let us quickly examine the evidence of its nutritional value.
Commonly, it is claimed that green tea somehow protects the body against various cancers – but a review of over 50 studies in 2009 involving over 1.6 million people found no evidence of any such protective characteristics.
The other claim is that green tea somehow helps people to lose weight – and again a study done in 2012 involving almost 2,000 people found no such effect.
There are other somewhat absonant claims about how green tea can prevent Alzheimer’s, lower blood pressure or reduce cholesterol – and research tends to support the view that any such benefits, if they exist, are inconclusive and currently not statistically relevant.
Curiously, a small study in 2014 (involving 30 young people) into the use of green tea as a mouthwash showed that rinsing with green tea is equally as effective as using a mouthwash containing the popular antiseptic chlorhexidine.
So it seems that green tea might be better as a good, cheap mouthwash rather than as a superfood.
On the other hand, a study on mice with induced myeloma (a form of bone marrow cancer) treated with the drug bortezomib (or velcade) found that green tea significantly interfered with the drug’s efficacy.
So it seems that green tea is probably harmless (unless you are on certain drugs), can improve your oral hygiene and is a drink one can ingest if one enjoys the taste.
But is green tea a super-healthy “superfood” guaranteed to nourish your body and extend life? The answer, based on currently available evidence, is simply: No.
That is not to say that green tea is actually bad for you – it is just that the range of nutrients in green tea by themselves appear not to have any verifiable significant health properties.
And the same verdict will probably apply to a whole bunch of other heavily-marketed “superfoods” if investigated in depth – interestingly, the real superfoods are just the usual vegetables and fruits you commonly get from the markets. There will be more on this later.
Many “superfoods” are also sold as (rather expensive) supplements and many such superfood supplements claim to contain high amounts of known antioxidants (usually beta-carotene, Vitamin A (retinol), Vitamin C (ascorbic acid), Vitamin E (a group of compounds called tocopherols and tocotrienols), selenium, et cetera – the story is that ingesting antioxidants is really healthy as antioxidants combat free radicals in the body.
In case you are not aware, free radicals are unstable molecules with an unpaired electron – and the body can make its own free radicals from oxygen metabolism or acquire them from food or the environment.
The unpaired electron means that a free radical can “give” or “take” an electron to/from another molecule – as such, free radicals are very reactive compounds that can damage proteins, cells and DNA in the body simply by reacting with other molecules.
There is also another class of compounds known as oxidants which are also reactive compounds and for the purpose of this article, oxidants are also classified as free radicals.
If you are curious, the free radicals most commonly associated with disease in the human body are hydroxyl radicals, hypochlorites, nitric oxide radicals, peroxynitrite radicals, hydrogen peroxide and superoxides. Note that the last two free radicals are also produced as by-products of the body’s own metabolism.
In addition, we ingest varying quantities of Advanced Glycation End-products (AGEs) every time we eat food cooked via the Maillard Reaction (ie. food cooked using dry heat at temperatures above 135°C) – and there are potentially hundreds of different types of AGEs in various foods with many of them known to be free radicals.
As expected, the story with antioxidants and free radicals is not as simple as it is often portrayed.
A famous study called Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) involving over 13,000 people in France over eight years and completed in 2004 found that antioxidant supplements appear to provide some protective benefits to men but not to women in terms of cancers and death rates.
The reason seems to be that men generally ingest fewer antioxidants in their diets than women and therefore the supplements appear to have a positive effect – conversely, if you’re already eating enough antioxidants, then taking supplements won’t help. But other research may have qualified the findings of this study – more on this later.
The body has its own mechanisms for dealing with free radicals ingested from food or derived from the environment (eg. from pollution or smoking) but it seems that our bodies needs a bit of help from our diet.
The main dietary antioxidants identified and utilised by the body are beta-carotene (a pre-cursor for Vitamin A), Vitamin A, Vitamin C and Vitamin E and these antioxidants work by either stably adding or subtracting a single electron to/from free radicals, thus curtailing the reactivity of many free radical compounds.
In addition, as superoxides are produced by the body’s own metabolism, this is handled by a family of enzymes called Superoxide Dismutase (SOD) which are based on trace metals such as copper, zinc and manganese – these enzymes deal with superoxides in much the same way as antioxidants, by safely adding or removing an electron to/from the superoxide, thereby restricting its reactivity to other molecules.
Hydrogen peroxide (another metabolism by-product) is managed by the enzyme catalase which decomposes hydrogen peroxide into gaseous oxygen and water.
Accompanying both SOD and catalase is the glutathione system of enzymes – these enzymes are featured most prominently in the liver and they are also responsible for neutralizing hydrogen peroxide and other peroxides.
The system also attends to organic hydroperoxides before they decompose into free radicals.
If you are interested, the gluta-thione system consists of gluta-thione, glutathione reductase, glutathione peroxidases, and glutathione S-transferases – and glutathione peroxidases are based on selenium which is why some superfood supplements also include this mineral.
Oxidative stress (or getting older faster)
If the number of free radicals overwhelms the body’s mechanisms for managing them, then it becomes a condition known as Oxidative Stress (OS) and this can happen from time to time over a lifespan – the frequency depends on lifestyle and diet.
Regrettably, even if OS became chronic, there are no initial symptoms for this condition – it only manifests itself rather slowly over time as cancers, inflammatory diseases (eg. arthritis, vasculitis, glomerulonephritis, lupus erythematous, et cetera), cardiovascular diseases, immune system diseases, high blood pressure, muscular dystrophy, neurological diseases (eg. Alzheimer’s, Parkinson’s) and a myriad of other illnesses as any part of the body may be affected.
Also, rhytides (skin wrinkles), macular degeneration and generally signs of faster ageing are common indications of OS.
Following up on the SU.VI.MAX study, a large scale review (published in 2012 by Cochrane) of all major research into antioxidants concluded that supplementary consumption of Vitamin E and beta-carotene (and Vitamin A) is linked with increased death rates of between 3 to 4% higher than normal – this is a statistically significant finding as the review covered almost 300,000 people.
Curiously, no negative findings have been reported with any consumption level of Vitamin C, so if you need more safe antioxidants, then eat a few more oranges or guavas, though it should be noted that Vitamin C only works on certain types of free radicals.
For some quirky reason, antioxidant supplements made me think of this silly story: Two dog owners were chatting and one said, “I saw this strange man picking up dog poop in the park today.” The other dog owner responded, “I don’t see what’s wrong with that. That’s what us dog owners do so our dogs don’t foul up the park.” To which the first dog owner replied, “But he doesn’t own a dog.”
The next part has some curiously good news about free radicals and (some more) bad news about antioxidant supplements.
Source: The Star
Photo: The Star/Filepic