Forbidden fructose

Not a day goes by without a well-meaning somebody reminding us that we don’t eat enough fruit and vegetables. The nagging of the nutritionists rivals that of my grandmother who used to force her famous “borscht” down my throat. The limp and tasteless bits of cabbage would stick to the roof of my mouth making me gag and my shaking hand would invariably spill the red liquid on her white tablecloth, resulting in an extra serving of beetroot goodness. I am obviously still deeply scarred.

The bright images of squeaky clean green apples and shiny red capsicums are often displayed in contrast to the pictures of insipid and suspicious-looking burgers with visible grease glistening on the meat patty, with horror movie music theme in the background. You have to be a moron not to realise which one is better for you, right?

Is it any wonder that a word “fructose”, which we immediately associate with “fruit”, sounds so wholesome? Fructose is indeed the predominant sugar in fruit. But it is a little more than that.

For something that sounds so healthy, fructose has been implicated in several nutritional crimes of late. Several studies have found that excess fructose consumption can cause insulin resistance in the liver, NAFLD (non-alcoholic fatty liver disease), gout, hypertension and abdominal obesity, colloquially known as a “spare tyre”. Does it make sense from physiological point of view?

Simple science

Actually, it does. While fructose is a simple sugar (=monosaccharide) just like glucose, it is actually processed in the body quite differently. After being absorbed from your intestine, it goes directly to the liver. The liver is like your body’s own Border Control. It receives raw materials, a.k.a. nutrients, from the gut, examines them for suitability (is it poison? is it a building block?) and then packages the good stuff up, loads them onto specialised freight trucks (transport molecules) and sends them via blood to customers, the cells in your tissues.

As you already know, the liver helps the pancreas keep the blood glucose on a tight leash, either by releasing more of it or by diverting extra glucose to fat stores. However, unlike glucose, fructose is too toxic to be floating around your body. Like a conscientious customs officer, your liver recognises the danger and neutralises it  by converting ALL fructose into triglycerides (fat). Triglycerides can be sent to the safe heaven of your fat tissues in their own trucks called LDLs (did you just have a little “Eureka” moment?), or they can be stored in the liver itself. Not good either way. Nobody likes love handles or their liver resembling fois gras.

Incidentally, do you know what else is processed in a similar way by the liver? Alcohol. So what would happen from a love match between alcohol and fructose? Bacardi Breezer, anyone?

Back to reality

Hang on, you ask, are you saying that fruit will make me fat and diabetic? No. The concentration of fructose in fruit is unlikely to harm you. In a manner of a true toxin, fructose has a dose-response relationship: the more you have, the worse it is.

The real question is: what other foods contain fructose? You are probably familiar with HFCS, high fructose corn syrup, a ubiquitous sweetener in the land of stars and stripes. HFCS is a product of industrial engineering genius: it is cheap, subsidised by the government (yay for corn subsidies) and is sweeter than sucrose, table sugar. It has been justly vilified and we often think we are lucky that it never took off in Oz.

However, your humble sucrose is not much better. HFCS normally used in soft drinks has 55%/45% fructose/glucose content. The white stuff that you put in your coffee is 50/50. Let’s say you don’t use sugar in your coffee and you don’t drink Coke, does it let you off the fructose hook? Sorry, no. Fructose is used in pretty much every processed and packaged product, whether on its own or as part of sugar. Fortunately for manufacturers, they don’t have to put fructose on nutrition labels. But you can estimate fructose content of foods yourself by dividing the amount of sugar on the label in half. (Be careful, it doesn’t work with dairy products, as their main sugar is lactose, not sucrose).

Here is a little table I prepared earlier.

  Sugar content (g) Estimated fructose content (g)
Apple green,
small

9.6

4.8

Apple juice,
250mL

26

13

Banana bread,
57g piece

14.7

7.4

Lipton Iced Tea, 375mL bottle

22.1

11.1

Nutrigrain
cereal, 40g

12.8

6.4

Coca Cola,
600mL bottle

63.6

31.8

As you can see, you have to have a hell of a lot of apples to come close to the level of fructose an average Australian/American consumes daily in the course of their processed food addiction.

What about fruit juice? Not too long ago fruit had to be squeezed by hand. Homemade juice sans the electrical juicer can be used as a babysitting tool: it will keep your kids busy for hours as they diligently work up a sweat trying to earn one glass of precious sugary orange liquid. If you want to be really mean, tell them to make apple juice by hand. Nobody in their right mind will eat 6 to 8 oranges in one sitting, but apparently a glass of juice, made from the same amount of fruit, is a healthy addition to our diet with breakfast, lunch and dinner.

Due to its current love affair with GI, Diabetes Australia tells diabetics that “a healthy eating plan for diabetes can include some sugar“. Glucose has a GI of 100, but table sugar, with only 50% of glucose, is 65. But the other 50%, fructose, is the real killer. Unfortunately, the very thing which makes the GI of sugar lower is the reason NOT to give it to diabetics. Its effects on the liver make it a ticking time bomb: you can’t see the blood glucose rise but your liver is developing insulin resistance with every bite of that low-fat banana bread.

So what do you do?
1. Whenever you drink soft drinks, juices, sports drinks, it is not just
the calorie load and fat-storing effects of insulin you have to worry about. It
is the direct toxicity to the liver. So don’t.
2. Avoid sweets and cakes with high load of sugar.
3. Avoid processed pre-packaged foods, bars, biscuits, as they have a lot
of hidden sugar.
4. If your goal is to lose fat, limit your fruit consumption to 2 a day.
5. If you have a diagnosed fatty liver, temporarily avoid fruit. It has
nothing that you can’t find in vegetables.

More information:
1. A must to see: “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. Series: UCSF Mini Medical School for the Public [7/2009] [Health and Medicine] [Show ID: 16717]
2. Dr Eades on sugar vs HFCS
3. Double danger of HFCS
4. Fructose content in popular beverages differs from data labels
5. Review: Fructose, weight gain and the insulin resistance syndrome

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20 thoughts on “Forbidden fructose

    • Thanks. I reckon most people had a gutful of generic “eat less move more” advice. Giving actual knowledge empowers people to make their own decisions.

  1. Nice one! Looks like my glass of juice in the morning just took a leap! Shame I packed in a few Smarties last night as well, damn! How about a little piece on Alcohol? Cos I like beer…. ;)

    • I am far from being a food nazi myself. I am quite partial to occasional ice-cream or a piece of berry cheesecake. What makes me see red is when foods that are not that great for us are misrepresented by dietitians/nutritionists/doctors and others who should know better. By all means have your orange juice in the morning. But let’s stop kidding ourselves that we are doing it for vitamin C. We do it because it tastes oh so sweet. I don’t see many people munching on a head of broccoli.

      • Brocolli no but does cauliflower count, and carrot and mushrooms… ? thats a habit I had as a kid, almost any vegetable can be eaten raw and I have not stopped since… sufficiently so my kids look for the raw stuff and munch into it as much as I do. Keep up the informative articles, they really help reset the head into what _is_ good/better for us.

        • That’s fantastic that you show this example to your kids. I get annoyed when parents preach fresh and natural food to their children but snack on junk themselves. I reckon you can tell what the parents eat by what their children nag for. And I don’t pretend to know all the answers. But unlike some others I am prepared to admit that I am still learning.

  2. I found your excellent blog from the link on Julianne’s Paleo & Zone nutrition blog. Good stuff! You’ll be a rare and exceptional doctor when you graduate. I adopted a Primal diet 2 years ago and have never looked back.

    • Thanks Judith. I am still under 1 year with this, but just like you I am not looking back. My eye-opening experience was reading Gary Taubes. Somebody said: once your mind is expanded by a new idea, it never goes back to its original size. My hope is to use this knowledge to help my future patients, and maybe even convince some of my colleagues (fingers crossed!).

    • Thanks Lyn, I actually have a book by Barry Groves, the author of this website, “Trick and treat: how healthy eating is making us ill”. I haven’t had a chance to check out his website yet. Good to see you are searching the net for truth. Keep it up!

  3. Nice post. I love the statement you make about nobody eating 6-8 oranges in one sitting yet the same amount for a glass of juice in the morning is so so good for us. Brilliant! I have thought about how natural fruit is (and I love my green apples) but before farming, orchards etc the ability to have it so on tap has always seemed a little more than we were probably designed for.
    Much of it seems to be more like a candy bar on a branch these days, with so much of it modified for sweetness?

    Hey have you seen Taubes cholesterol results? With your knowledge could you do an overview of what they mean.US numbers converted for us here in Australia. I watched the Dr Oz show with GT on YouTube and was not surprised they tried to railroad him. The Dr Oz show is so far removed from fact its crazy.

    Like your style.

  4. Hi Anastasia,
    Thanks for the interesting article! I’ve watched Dr. Lustig’s presentation recently, and when looked for further information reached your site..
    I wanted to ask what do you think about natural home made juices (for example carrots, apples..)? I’m not talking about 8-10 carrots of course, but about a glass of juice a day (let’s say 2 large carrots+ one apple).
    From the presentation i understood that the fiber in fruits and vegetables acts as an “antidote” to the fructose, so the home made juice is not supposed to be so healthy as i thought, but where do you draw the line!?
    Thanks!

    • Hi Dana. I think you have to ask yourself why you are having that glass of juice in the first place. A glass of homemade apple juice contains some vitamin C, polyphenols (for antioxidants), some starch and some boron (for bones). Does it counteract the amount of fructose in it? I guess it depends on the rest of your diet. It is a question of the risk/ benefit ratio. If the rest of your diet is free of potential liver toxins (fructose/sugar, alcohol, wheat and rancid oils), an occasional glass of juice won’t harm you. If you have weight/diabetes/elevated liver enzymes it is probably an indulgence you cannot afford.
      Are you better off eating an apple? Yes. Does a glass of juice taste nice? Yes. It is a cut above iced tea and coke, no question. By the way, carrot juice, in my opinion: benefit > risk.
      Dr Kurt Harris calls modern fruit “candy from the tree”

  5. Pingback: Q&A on fructose, soy and meal frequency | primalmeded

  6. “Like a conscientious customs officer, your liver recognises the danger and neutralises it by converting ALL fructose into triglycerides (fat).”

    Buzz. Wrong. Sorry. Unless you meant at rest in “typical sedentary individuals in chronic positive energy balance”

    I have data which shows that during exercise, fructose is converted to lactate and released into the blood and is also converted to glucose in the liver for HGO. If you look at some recent papers from Jeukendrup, they show that fructose when combined with glucose is actually beneficial to performance, does not increase TAG production in the liver, etc. I think you are missing the energy balance side. If you make carbons go places (AKA exercise causing substrate to move to CO2) you don’t have a reason to make fat (given that you are not in chronic positive energy balance). The fructose ingested prior to and during exercise is used to maintain blood and liver glucose/glycogen respectively and post exercise is an excellent source for liver glycogen re-synthesis.

    I can provide references upon request.

    Also, Lustig takes high point too far and actually has some fallacies in his speech as well. See http://rdfeinman.wordpress.com/2011/07/29/wait-a-minute-lustig-the-threat-of-fructophobia-and-the-opportunity/

    Looking forward to a response.

  7. 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
    disappeared.
    I do eat more meat now, and occasionally have an alcoholic drink, and thank God everything
    seems to be fine.
    Fructose was my enemy.

    • Hi Tony, I wish more doctors were aware of the link between gout and fructose. The traditional recommendation is to reduce alcohol (fair enough), seafood (?) and eat a “healthy diet”. And yes, many patients interpret healthy diet as high in fruit and fruit juices. Congratulations on getting your gout under control.

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