Is purple grape juice really the answer to all our ills?

I was interested recently to read the results of the study which assessed the ‘antioxidant’ potential of several types of fruit juices and fruit drinks [1]. Of the 13 types of fruit juice tested, red grape juice came out on top with regard to antioxidant action, which appears to be related to its rich content of potentially disease-protective plant substances known as ‘polyphenols’. This study has led to purple grape juice being hailed as the king of fruit juices.

However, before we go scootling down to the supermarket for a dose of this latest superfood, we might do well to consider purple grape juice’s prime constituent ” sugar.

Like all fruit juices, purple grape juice is rammed full of the stuff. One prominent brand contains 40 g of sugar per 240 ml serving. That works out at 16.66 g of sugar per 100 mls of drink. Coca-cola, on the other hand, contains 35 g of sugar per 330 mls. Which works out at 10.6 g of sugar per 100 mls.

What this means is that purple grape juice contains more than 50 per cent MORE sugar than Coca Cola.

Could it be that this glut of sugar might offset some of the healthy properties ascribed to the polyphenols in purple grape juice? That’s a rhetorical question, obviously.

The sugar in fruit juices such as purple grape juice comes, essentially, in the forms of glucose and fructose. As I have written before on this site and elsewhere, while fructose is often seen as a ‘healthy’ form of sugar, the evidence suggests that it is anything but.

Just this week, for instance, a study was published which showed the considerable potential this form of sugar has to harm health. The study, published in the journal Hepatology, fed rats with a sugar solution containing either glucose or fructose [2].

Two notable effects of feeding fructose to rats were:

* Increased fat production in the liver

* Reduced effectiveness of the protein ‘leptin’ (among other things, leptin reduces fat production and enhances fat burning in the body)

In this study, some of the negative effects of fructose were found to be the result of impairment of the function of a receptor known as PPAR-alpha. This receptor is present in humans, and its activity in our species is lower than that in rats. This led one of the authors of the Hepatology study to speculate that the effect of fructose in humans should cause even worse effects than those revealed in rats.

There seems every reason to believe that the consumption of fructose might contribute to the rapidly rising rates of obesity seen around the World.

Take all of this together and there is good reason, I believe, for individuals to consume fruit juices with caution. Focusing on their polyphenols content and antioxidant activity simply does not give a full picture of their nutritional attributes and likely effect on health.

It should perhaps be borne in mind that the recent study highlighting purple grape juice’s wonderfood credentials was funded by an organisation known as the National Grape Co-operative, a consortium of US farmers operated by Welch’s who produce (you guessed it) purple grape juice.

Regular readers of this blog may remember that I recently reported on a study which found that studies funded entirely by the beverage industry are some 7½ times more likely to report favourable results than research which has received no industry funding [3].

References:

1. Roglans N, et al. Impairment of hepatic Stat-3 activation and reduction of PPAR activity in fructose-fed rats. Hepatology 2007;45:778-788

2. Mullen W, et al. Evaluation of Phenolic Compounds in Commercial Fruit Juices and Fruit Drinks. J Agric Food Chem. 2007 Mar 16; [Epub ahead of print]

3. Study reveals the potential for the food industry to pervert the course of science

12 Responses to Is purple grape juice really the answer to all our ills?

  1. Karen 23 March 2007 at 8:23 pm #

    Have it occasionally and cut it with fizzy water…

  2. Richard 24 March 2007 at 3:06 pm #

    I would not compare good quality fresh grape juice to cola. It is rich in sugars but I suspect Welch’s grapes are also hybridised and selected for sweetness, also pasteurization increases the simple sugar content of foods. Chilled homemade, fresh juice from non-hybridised grapes (with viable seeds) is a great treat.

    Be aware when you are being manipulated by marketing, all fruit and veg have anti-oxidants especially the fresh uncooked stuff. There are loads of free wild foods like dandelion leaves to add to salads and get berries from hegderows in August. Get a wild foods book and get out walking, it beats the supermarket on a Saturday morning.

  3. Miss Sylvia Wainhouse 24 March 2007 at 4:39 pm #

    Coco Cola may contain less sugar than grape juice but it also contains phosphates which inhibit the absorption of calcium.

    Furthermore, the sugar in Coke is ‘extrinsic’ and therefore can cause fluctuations in blood sugar levels, which often result in sugar cravings – “more Cola” – and over-eating of the ‘wrong’, i.e. non-nutritious, foods.

    Fructose is an ‘intrinsic’ sugar and therefore prevents fluctuations in blood sugar levels.

    I suggest you drink grape juice for its antioxident qualities and dilute it with still (preferably) or sparkling water. It’s much more refreshing drank that way and beats Cola hands down!

  4. Dr John Briffa 25 March 2007 at 9:57 am #

    Thanks Richard and Sylvia
    I too believe that grape juice is healthier than cola – but just used cola to show how sugar-rich fruit juices like grape juice are.
    The idea of diluting fruit juice with water is, I think, a very good one.

    Sylvia – sugar in fruit juice is classed by the Food Standards Agency here in the UK as an ‘extrinsic’ sugar.

    The low impact that fructose has on blood sugar levels has some relevance, but the point is that fructose does pose very significant hazards for our health.

  5. Christina Naylor 16 January 2008 at 10:51 am #

    According to Jane Feedman M.D., Asst Prof. of Medicine and Pharmacology, “plateletsmin purple grape juicereleased 55%less superoxide..a free radical..which quickly inactivates the beneficial effects of nitric oxide”. It also contains the flavonoid Quercitini, which inhibits platelet activity. P.g.j.concentrate was declared to have this effect t the American Heart Assn’s 71st Scientific sessions in 2002.

    According to Dr Folts, p.g.j. also dilates the arteries. Any comment?

  6. David 6 April 2009 at 7:30 pm #

    If you are looking to improve your health with polyphenols and anti oxidants without the negative effects of the sugar content perhaps you should check out wine. Dry wine is filled with both polyphenols and anti oxidants both red and white. It also contains very little sugar as it has all been turned to alcohal. Of course, massive consumtion of alcohal has many ill effects. A recent article I read suggested that the average adult male can consume two drinks and a female one drink of alcohal in a day without any ill effects of the alcohal.

  7. Steven 3 August 2009 at 8:56 pm #

    I also like to drink grape juice for the health benefits, but like Sylvia, I, too, cut it (with seltzer) because it is way, way too sweet. Sometimes I wonder if the companies are re-constituting it from concentrate properly!

  8. Janar 5 November 2009 at 2:03 am #

    I was reading your post and it hit me that I might be getting too much sugar from grape juice Im drinking. Although, grape juice is one of the richest source of chromium which helps with sugar metabolism and insulin. It could give the benefit for getting the sugar from grape juice metabolised effectively.

    Thanks for the article, it was really informative.

    Janar

  9. W. D. Fenwick Jr. 3 April 2010 at 2:15 am #

    Where might I obtain sugar free red grape juice?

  10. PhilT 28 May 2013 at 7:53 am #

    I see Welch’s purple 16.5% sugar solution, sorry – “grape juice” – is carrying a “Heart UK” logo – “Supporting Heart UK, The Cholesterol Charity” to indicate their £40k sponsorship.

    On the radio on Saturday I heard a cardiologist declaring that we were being “poisoned with fructose” and yet here’s a Heart health “charity” endorsing a purple sugar solution.

    The medical ecosystem needs to get its act together on sugars of fruit origin – is grape juice going to lower my cholesterol or poison my heart ?

  11. Sean 1 June 2013 at 5:20 am #

    This article is an example of the lunacy of making grand generalizations from information extrapolated from generally useless scientific studies that bear absolutely NO resemblance to real-world human dietetics.

    Please explain to me how feeding RATS a sugar solution (which means an extremely high percentage of their daily diet, if not all of it- we don’t have that information here) of EITHER fructose OR glucose for a short period of time, and then using the results of that experiment to bash fruit juice makes any kind of sense whatsoever??

    A few things come to mind:

    1. Fructose ALWAYS comes packaged with glucose in nature. You cannot find pure fructose foods naturally, so therefore, this experiment is already useless. A gazillion studies show that the presence of glucose modifies how fructose is metabolized in the body and vice versa. Sorry about that to Dr. Lustig as well.

    2. Grape juice has a number of nutrient co-factors that are not found in the PURIFIED fructose and glucose studies done with RATS. This – especially the effect of potassium on sugar metabolism – is, of course, completely ignored here. Grape juice does indeed contain the evil sugar (ignoring the fact that sugar is the primary source of energy for all of our cells), but also contains nutrient co-factors that assist and effect the metabolism of that sugar, which Rat Aid does not have.

    3. No human consumes anywhere near the percentage of purified fructose or glucose as the rats did in the study. Humans, in general, consume a rather wide diet that might consist of a certain amount of fructose, along with glucose.

    4. People like Lustig, for example, and others who bash fructose, ignore the fact that sugar has been used in moderate amounts for centuries, whereas the only new food, eaten in mass quantities, that could easily be blamed for the metabolic and mitochondrial degeneration seen over the last couple of generations, is most likely rancid PUFA from the so-called “heart healthy” polyunsaturated vegetable oils; industry created “products” which are unequivocally toxic and promote cancer, diabetes, and degeneration; whereas fruit (and fructose) has been eaten by man and animal since the beginning of history,

    Missing the big picture while focusing on silly, useless, reductionistic experiments and then making baseless generalizations is exactly why blogging and other health propaganda bandied about on the internet is so much more dangerous than a glass of grape juice…

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