Fructose found to rapidly raise blood pressure and induce metabolic syndrome in men

Last month, one of my blogs focused on a paper from the American Heart Association which warned of the hazards of eating sugar on cardiovascular health. It put at least some focus on the sugar fructose, which makes up half of table sugar (sucrose), as well as being found in fruit and vegetables, honey and foods containing (obviously) the sweetening agent known as ‘high fructose corn syrup’. Fructose has traditionally enjoyed a healthy reputation, related to the fact that it does not raise blood sugar levels in the short term, and is also found naturally in foods such as fruit. However, mounting evidence suggests that it has the potential to induce seriously unhealthy changes in the body.

By way of example, today I am writing about a study presented this week at the American heart Association’s High Blood Pressure Research Conference in Chicago, USA [1]. In this study, 74 men (average age 74) were fed 200 g of fructose on top of their normal diet. Half of these men were also treated with the drug allopurinol ” used to prevent gout because of its ability to reduce levels of uric acid. The active part of this study last just two weeks.

In the men eating additional fructose without concomitant allopurinol treatment, blood pressure rose significantly (6 and 3 mmHg in systolic and diastolic pressure respectively).

At the beginning of the study, 19 per cent of these men fulfilled criteria qualifying them for the diagnosis of metabolic syndrome (a condition characterised by a range of potential issues including excess weight around the midriff, high blood pressure, raised blood sugar and raised levels of blood fats known as triglycerides). At the end of the study, this figure had risen to 44 per cent (in just two weeks, remember). Notable changes were rises in triglyceride levels, insulin levels and measures of insulin resistance, as well as lowering in supposedly ‘healthy’ HDL levels.

Men treated with allopurinol saw no increase in blood pressure ” suggesting that allopurinal can mitigate against at least some of the toxic effects of fructose.

The 200 g of daily fructose used in this study is a large dose (apparently, the estimated average daily intake in the USA is 50- 70 g). However, it’s useful to remember that this is an average, and it is likely that significant numbers of people will be consuming way in excess of 100 g of fructose each day. And also, it’s worth bearing in mind that fructose was fed to individuals for just two weeks. It is possible that lower doses of fructose in the longer turn might turn out to be similarly damaging.

Clearly, what this study does demonstrate, again, is that fructose poses significant hazards for health, and is something that needs to be consumed with caution. The real issue here is almost certainly not the carrots or piece or two of fruit we might eat each day, but the sources of fructose added many processed foods and, in particularly, sugary soft drinks.


1. Perez-Pozo S, et al “Excessive fructose intake raises blood pressure in humans” AHA Blood Pressure Research Conference 2009; Abstract P127.

28 Responses to Fructose found to rapidly raise blood pressure and induce metabolic syndrome in men

  1. Rebecca 25 September 2009 at 11:08 am #

    Do you have a view on Agave syrup as an alternative to sugar? There seems to be differing views as the whether this is a healthy option?

  2. Ted Hutchinson 25 September 2009 at 11:33 am #

    In case readers here haven’t yet seen this 89minute you tube video it really is worth watching.
    Sugar: The Bitter Truth Robert H. Lustig, MD, UCSF Professor of Pediatrics in the Division of Endocrinology, explores the damage caused by sugary foods. He argues that fructose (too much) and fiber (not enough) appear to be cornerstones of the obesity epidemic through their effects on insulin.

  3. Dr John Briffa 25 September 2009 at 11:58 am #


    Agave syrup is rich in fructose (I believe), and like other sources of sugar is likely to pose hazards for health, and I think should be consumed in very limited quantities.

    If anyone has any evidence to the contrary on agave syrup, please share.

  4. Elizabeth 25 September 2009 at 12:56 pm #

    I’ve just started taking a spoonful of manuka honey twice a day as I’ve heard of it’s many health benefits. I’ve encouraged my husband and grown children to do the same. Is this dangerous?

  5. Antje 25 September 2009 at 1:36 pm #

    200 GRAM fructose on top of a normal diet?!?! Of couse this damages one’s health, like all excesses. Like drinking 8 liter of the purest natural water could kill you.Dr. Briffa, this report does not in my opinion stand in your fine tradition: taking a critical look at scientific investigations. I always read them with great interest.

    200 grams fructose is how much fruit of honey ?

    PS A couple of years ago women died after eating nutmeg. Does that mean nutmeg is dangerous? No, she grated A WHOLE nutmeg, sprinkled it over her meal and consequently died. She must have been nuts.

  6. Dr John Briffa 25 September 2009 at 1:50 pm #


    I think I did concede that 200 g of fructose is a LOT of fructose in the blog post. But the speed of the changes, plus the context (plenty of evidence that fructose is potentially toxic) make this study noteworthy, I think.
    Though I respect your right to disagree.

  7. Matt Brody 25 September 2009 at 5:07 pm #

    “Agave Nectar” is not only higher in fructose than HFCS (70% or more, compared with 55% for HFCS if the linked brand is typical (

    Weston A Price Foundation has come out squarely AGAINST Agave. In addition to the lack of health benefit, they are concerned that is being sold as a premium proudct when in fact it is processed similar to HFCS.

  8. Matt Brody 25 September 2009 at 5:07 pm #

    Sorry, bad link there for Weston Price.

  9. Antje 25 September 2009 at 6:20 pm #

    Dr. Briffa,

    thanks for your reaction.

    Is fructose toxic even if eaten in its natural context as part of fruit?

    This question is of particular interest to me because i am allergic to all grains( even quinoa) and therefore fruit and honey are my sources of carbs. i do a lot of sport so i need my carbs. Thank you.

  10. Dennis Mullins 25 September 2009 at 8:41 pm #

    The problems with digestion of fructose (and fructans) are well known.

    Fructose is a food extract and does not occur on its own in nature ” it is not surprising that eating it on its own causes detrimental effects.

    However ‘fructose, as part of the intricate structure of whole fruit, is easily digested. Whole fruit can be processed to extract components but the fruit is not ‘made’ from the components (you can’t reconstruct fruit from its extracted components !!} ” fruit is a low entropy highly ordered organic structure which has been grown in (very low entropy) sunlight according to its DNA. Eating whole fruit, as consumed by our ancestors for thousands of years is very beneficial to health.

    Adding glucose to fructose can actually make it more digestible but the combination is still not beneficial in the same way as whole fruit or vegetables.

    The conclusion is ” eat good amounts of all types of WHOLE fruits and loads of vegetables as they are cancer protective and very beneficial to health ” do not worry at all about their fructose content. Completely avoid eating extracted fructose and HFCS as well as all refined sugars, refined grains and refined fats/oils.

  11. Susan 26 September 2009 at 1:16 am #

    what about prunes, dates, and dried fruits, which have high potassium content, which is supposed to help lower high blood pressure?

  12. Malcolm 26 September 2009 at 2:12 am #

    Why not use potatoes, sweet potatoes, bananas and root vegetables for your carbs?

  13. nualan 26 September 2009 at 10:32 pm #

    dr briffa, are goji berries as healthy as we are to believe?

  14. Jake 27 September 2009 at 3:36 am #

    Fructose is fructose no matter what the source whether it be from sugar, honey or fruit. You should limit yourself to 25 grams of fructose a day. Any more and you are putting your health at risk.

    I only eat berries which have a relatively low amount fructose to the volume of fiber.

  15. Rebecca 27 September 2009 at 1:39 pm #

    Thank you Matt for the Weston Price link – very interesting reading, espeically the part about the light and dark versions of Agave.

  16. Terry H 27 September 2009 at 3:07 pm #


    Your views expressed above re- fructose appear to be related to issues associated with it’s absorption in the gut, not fructose metabolism, which is essentially (as I understand it) an issue associated with the workings of the liver, once it has been absorbed though the gut.

    I cannot see how what you describe impacts the adverse impact that fructose “overconsumption”, whatever that might be, has on processing by the liver, as postulated in the paper referred to in this post, as argued in Lustig’s polemical video at:, or as also cogently argued using the science by David Gillespie in his recent book “Sweet Poison”.

  17. Dennis Mullins 29 September 2009 at 3:35 am #

    Jake, Terry H
    On average fresh fruit has about 5 g of fructose per 100g – thus one can eat 500 g of mixed fruit a day without exceeding 25 g of fructose. This corresponds to several pieces of fruit. Fruit has huge health benefits. The equivalnt Sugar or HFCS eaten alone has no health benefits and indeed depletes the body of nutrients and causes inflammation. Eat fruit – not sugar or HFCS. Dried fruit is also OK if no fresh fruit available but should be consumed in much lower quantities

  18. Trinkwasser 29 September 2009 at 8:55 pm #

    I’ve seen some evidence there’s a U curve or J curve with fructose – SMALL quantities, such as you may find in a small quantity of fruit, may be beneficial but the kind of quantities in an average diet full of sugar or HFCS are considerably toxic.

    I’ll do a few strawberries or blueberries, or half an apple, which doesn’t spike my blood glucose. Above that kind of quantity fructose evades the BG control system and is strongly implicated in metabolic syndrome/insulin resistance, fatty liver etc.

    Amazing that the AHA are finally looking for culprits other than saturated fat!

  19. Rebecca 21 October 2009 at 5:01 pm #

    I am not sure if anyone is still following this thread, but I wrote to the manufacturers of the Agave syrup I use (The Groovy Food Company) and got this reply – which I have permission to reproduce. This seems to totally contradict the Weston Price report, but I am happy to continue using this product, but as with everything sweet, in moderation only. I should add I have no connection with the manufactuers of this product, and have no interest in promoting their product, I am just trying to give an alternative view. I also understand if this blog comment is too long to publish.

    “Our Agave Nectar is the product of the organically grown Blue Webber Agave Plant in Mexico. After harvesting, the large pineapple shaped core of the plant, known as the pinas, is crushed and milled. All raw juices are collected. The juice then undergoes a process of filtering to various levels to produce the Rich Agave Nectar and the Mild, the mild being filtered for longer and hence the lighter colour. The rich agave nectar is darker simply because it is filtered for less time and not as the article states, because it has been burnt! The filtered product then undergoes hydrolysis, gently heating the juice to a maximum of 161 degrees F (70-72 degrees C). This is the final stage in the production of the Agave Nectar.

    We have visited the manufacturer in Mexico and seen for ourselves the high standard of the manufacturing process which allows us to confidently import the product into Europe.

    The organically grown Agave plants are cultivated and produced without the use of chemicals or genetic modification. At no stage of the manufacturing process is the Agave juice either refined or exposed to or treated with chemicals. The Agave Nectar is produced organically and certified by a European recognised body. The product has full traceability.

    For every batch produced we receive full certificates of analysis and samples for approval.

    We also ourselves independently test these samples with an accredited UK based Analytical Consulting Chemist.

    We must emphasise that we only import from accredited organic suppliers in Mexico and we are therefore unable to comment on websites that make claims about the manufacturing processes undertaken by non- organic producers .

    There is a great deal of negative press surrounding fructose but this is the fructose found in High Fructose corn syrup, manufactured using chemical processes and high refining. Agave Nectar fructose is completely different, ours being organic and natural and manufactured without the use of any chemicals or refinement. They are very different products but increasingly Agave Nectar is being linked and confused with High Fructose Corn Syrup.

    We have also heard about several US companies buying Agave in bulk and ‘watering it down’ with high fructose corn syrup.

    Concerns about the consumption of fructose have grown steadily over the years due to the increasing amount of High Fructose Corn Syrup that is now increasingly used by the food industry, especially in the US. It is a highly refined chemically produced sweetener used in most fizzy drinks and processed foods. Its addition to so many products has lead to many receiving very high doses of High Fructose Corn Syrup on a daily basis. We are unable to comment on the effects of High Fructose corn syrup as it is not a product we would ever include in our foods and it would be unethical for us to make any negative claims. However, it is unfortunate that such a refined fructose is so often confused with a natural organic syrup that has long been used in moderation as a sweetener.

    Critics of the article you sent us have also claimed that the comments made by the authors, follow laboratory testing which involved massive doses of pure clinical fructose being fed to rats regularly. This is not the same as the normal moderate daily use of agave nectar in the course of our meals.

    Our Agave Nectar is a natural and organic product which is completely free from chemicals and refinement in the manufacturing process used in its production. Although high in natural fructose, it is an excellent alternative to refined sugar and artificial sweeteners. It has a very low Glycaemic Index and is a slow release carbohydrate which will keep the blood sugar levels balanced and allow the body to absorb it slowly, avoiding the usual sugar rush we associate with sugar, which allows its use by diabetics. Agave Nectar is a sweetener and ideally used in moderation and not in very high doses.
    Please do bear in mind that Agave Nectar has been used for many many years in the US before it became popular in Europe and then the UK. In that time, people have been enjoying it without concern as an alternative to sugar.

  20. Enrique 16 January 2010 at 12:55 pm #

    Dear guys:

    I am sending you the abstracts of the fructose study.

    Best regards.


  21. simona 28 January 2010 at 1:55 pm #


    I’m replying because recently I’ve seen agave again on the TV in a cooking programme. Many people are pushing agave as being healthier than sugar. It is not. High fructose corn syrup or high fructose agave syrup seems to me to be similar in composition. That corn is more processed is not that important in your body. People don’t generally get organic, ‘raw’, minimally processed, gently heated agave. Maybe they even get the one mixed with HFCS.

    Of course they are defending their product, however, they seem to emphasise the fact that their process doesn’t involve chemicals and that they don’t use pesticides and not that the composition of the syrup is that different. Everybody talks about the low GI of the agave syrup. Fructose is metabolised differently than glucose, hence the low GI but we can see (from the article above and the references given) that it is worse than glucose.

    I don’t know if it’s worth comparing honey, blackstrap molasses, (that even contains some trace minerals) table sugar, agave, or HFCS. I would put them in this order but the idea to keep fructose under 25 g a day is more important. Get fructose from a piece of fruit or some berries depending on season and have a small dessert with a bit of sugar once a week to avoid feeling deprived (if you do) or very dark chocolate (10 grams of fructose per 100 g).

    For a different perspective, have a look at this:

  22. Tony Phylactou 28 November 2011 at 1:58 am #

    I had my first gout attack about 10 years ago.
    At the beginning I was having attacks every 6 months. Then gradually I was getting them
    every 3 months, then every month and eventually every week.
    It started at my big toe and then it was moving sometimes in my knees,and generally all
    around my joints, in my feet.And the pain was agonising.
    I have tried all the cures you can imagine.I tried ACV, lemons, drinking a lot of water, but
    to no avail.I tried water fasting, juice fasting,baking soda, again without success.
    I almost gave up meat, limiting it to only once a week ,gave up alcohol completely,again
    no success.
    I was living on vegetables, lots and lots of fresh fruit, milk ,cheese beans and so on .My
    eating habits could not be healthier ,or so I thought.But my gout was worsening.
    Then I decided to increase the amount of fruit I was consuming, thinking that if some fruit
    is healthy, more fruit will be more healthy.Some days I was eating fruit only ,others over 10
    portions a day.
    And alas my gout instead of improving it became chronic ,it was there all the time.
    I was desperate I did not know what to do.
    And then one day accidentally I read an article about fructose,which is contained in fruit in
    large quantities.It said that it increases uric acid, in a matter of minutes.
    Fructose is also present in table sugar, and in HFCS, which is used in soft drinks.
    I put two and two together and realised what I was doing wrong.
    I stopped eating fruit and all other sugars, for a period of 3 weeks,and by magic I saw a
    dramatic improvement.Pain was gone, swelling was gone, I was fine.
    I re introduced fruit again in my diet but reducing them to 1 or 2 a day, and my gout completely
    I do eat more meat now, and occasionally have an alcoholic drink, and thank God everything
    seems to be fine.
    Fructose was my enemy.

  23. raeraj 12 January 2012 at 9:46 pm #

    The article says that fruit is not a concern, but what about on a frutarian diet where one eats up to 6000 calories all in fruit? Is that a lot of fructose? There’s a diet out there called 80 10 10 that is not popular but it does have a hold on some people and this is what they do.

  24. Nefi 4 July 2012 at 9:37 am #

    I have an intolerance to fructose that I first discoved eating a large number of grapes two night in a row that caused me to bloat and have an upset stomach. I notice the feeling if I eat/drink anything with a high fructose content… grapes, plums, cherries, dried fruits, soft drinks are all off my list as they cause me to bloat and make me sick.


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