Wednesday, April 20, 2011

WTH Are Flavonoids? Should You Care?

Flavonoids sound more like a 1950s space monster invading our planet to take our women, but it turns out they are just a reputedly healthy group of naturally-occurring polyphenols found in certain foods.  Now, to be clear, those results are from epidemiological studies, which some might describe as voodoo.  So, I take such results with a grain of salt.

First, if you want Flavonoids, what is the best dietary source?

Is Green Tea Really The Most Flavonoidtastic Choice?

Well, that is an interesting question.  Aside from green tea, some commonly-discussed sources are citrus, red wine, and dark chocolate.  You can run comparisons of the content and, depending on the source and specific product chosen, you will likely find data suggesting that red wine has as much as twice as many flavonoids per mL than green tea and 71% cocoa dark chocolate (the most plentiful chocolate source) five times as much.

But green tea lets you intake flavonoids without taking in sugars and if 197 mL of red wine is enough to achieve produce health benefits (a generous glass of wine), then three cups of green tea a day should easily achieve the same effect without the sugar or intoxication.  For a daily routine, this makes green tea a pretty good deal.

And sorry, chocoholics, you only need 59 g of the 71% cocoa dark chocolate per day to achieve health benefits, which is approximately one small bar.  Also, that small bar probably contains around 80 mg of caffeine (depending upon how it is manufactured), which puts it on par with the daily amount you would get from a healthy amount of green tea.

So, What Flavor Suits You?

It comes down to what comes along for the ride, nutritionally-speaking.  Red wine will bring sugar and alcohol.  Green tea will bring caffeine.  Chocolate will bring caffeine and sugar.
  • No sugar = green tea
  • No caffeine = red wine
  • I want choco! = dark chocolate

    Lots of Wiggle Room

    Not all flavonoid sources are created equal.  Web pages have a variety of information, but let's see what the USDA Database for the Flavonoid Content of Selected Foods, Release 2.1 has to tell us.  For example, let us consider the caffeine content of 100 mL of brewed green tea:
    • Total Mean: 133 mg
    • Total Min:14 mg
    • Total Max: 484 mg
    Now, of course, that may be artificially extreme, as one tea may not have the maximum value for all flavonoids at once.  But still, it is a strong message of "your mileage may vary."

    Should You Care About Flavonoids?

    Aside from being a healthy excuse to drink wine and eat chocolate, what use are flavonoids?  There are claims of antioxidant capabilities that may reduce cancer incidence.

    To be honest, I am not overly impressed.  If you are consuming the above foods to get flavonoids, then you may be wasting your time.  When you dig deeper, the studies tend to be epidemiological correlations, which are not the most robust thing.

    For example:
    1. Ask a bunch of people how much green tea they drink
    2. Look at what diseases they have
    3. Compare the incidence of disease to the consumption rate and look for correlations
    4. Report those correlations
    Let's say that you find a correlation that people that drink green tea are less likely to die of some cancer.  So, you open up a lot of questions, like:
    • Is the drinking of green tea the relevant data point or is it some other thing that is common among people that drink green tea?
    • How honest/accurate where the respondents?
    • How robust is the result?
    A lot of the data is based on in vitro (essentially, in a petri dish) experiments.  While I wish it were not true, experimental accuracy declines as you go from human test to animal tests to in vitro tests.

    This quote from the WebMD page on coffee does a good job of concisely saying what I mean:
    Researchers don't ask people to drink or skip coffee for science's sake. Instead, they ask them about their coffee habits. Those studies can't show cause and effect. It's possible that coffee drinkers have other advantages, such as better diets, more exercise, or protective genes.
    To give a more visceral example, let's consider the myth that you can cure drunkenness with coffee.  How did that start?  Well, in The world of caffeine: the science and culture of the world's most popular drug, the authors suggest that simply displacing a steady diet of beer contributed to this.  They report records of German sailors routinely downing three gallons of beer each day.

    So, imagine the German sailor of yesteryear who simply started drinking coffee or tea instead of some or all of that beer.  They would probably lose weight and be less likely to die of complications of alcohol.  Oh, and be less drunken.  Did the coffee protect them or simply take the edge off of their excessive consumption of beer, thereby avoiding many problems?  And therein lies the problem.

    Are There Flavonoids In Them Thar Guts?

    Having lots of antioxidants in a substance does not necessarily mean that if you consume it, you will have similar amount appear in your blood stream.  The European Food Safety Administration reported the following in 2010:

    On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of the food(s)/food constituent(s) evaluated in this opinion and a beneficial physiological effect related to antioxidant activity, antioxidant content, or antioxidant properties.
    On the basis of the data presented, the Panel concludes that a cause and effect relationship has not been established between the consumption of the food(s)/food constituent(s) evaluated in this opinion and the protection of body cells and molecules such as DNA, proteins and lipids from oxidative damage.
    If you like conflicting data, check out this line from the Wikipedia page on the Health Effects of Tea (note I am not saying Wikipedia is self-conflicting; they are merely, and rightly, reporting conflicting data):
    One study[58] shows that green tea reduced the severity of rheumatoid arthritis in rats; however another study[59] shows that tea increases the risk for rheumatoid arthritis by 78% for heavy drinkers and by 40% for occasional drinkers.
    So, yeah, not the rock solid cause and effect data I would prefer to see.  Heck, some of the positive mental effects may simply come down to those people liking a hot cup of tea and/or the stabilizing benefits of the daily ritual of making and consuming it.

    Final Thoughts

    This leaves even more of a mystery as to why someone would want you to add green tea to every meal.

    So, should you seek out flavonoids?  Well, if it will cause you to displace something unhealthy, i.e., drinking green tea instead of a gallon of beer, then heck yeah!  But should you make a point of getting the flavonoids?  Meh, I am not so sure.

    And if I do want flavonoids, I think I'd rather go with red wine. :)

      No comments:

      Post a Comment