Thursday 16 October 2008


As anyone who has been part of the raw food world for a while will know, it does seem that, for just about everything that passes our lips there's Raw Food Expert X who tells us it's an essential part of our diets, and Raw Food Expert Y who tells us what harm it will do us, or, at the least, that it's not an 'optimal' food.

And here we all were (or many of us) wedded to our smoothies - banana smoothies, green smoothies, everything-but-the-kitchen-sink smoothies, then along comes Raw Food Expert B who makes our little mouths turn down with his comment that smoothies should be regarded as 'recreational' rather than 'nutritional' drinks and that over 80% of nutrients are lost through blending. Can't be true, or can it...:-(

So, every so often at RawforLife, I look at a food/class of foods and present a range of arguments for and against. My objective is to provide information for Raw Food Independents - those who prefer not to follow everything one human being says, and like to make their own decisions. And yes, this time it's smoothies, or, let's say, blending in general.

Before I start, for those who aren't sure (and not everyone is), when we say blending we mean liquidising food in a blender(also known as a liquidiser).

So here are the blending pro's and cons - I think I've got them all...


All the fibre is retained, and, if you like, the peel and/or seeds. So that should mean that more nutrients are retained in blending than juicing. And the presence of the fibre helps the food move through our bodies easily.


Good in some ways...

During digestion our bodies turn food into a liquid so that nutrients may be easily absorbed and assimilated. The first stage of this process is chewing, and the second is when water and gastric juices mix with the food. The blender does at least some of this work for us, saving us energy.

Also, to release nutrients from cell walls of green leaves we need to chew to a creamy consistency (although in reality most people probably don't chew long enough to do this). Some claim that a blender can break down these cell walls, making nutrients such as lycopene (in tomatoes) and betacarotene (from carrots) more available to us.

Blenders are also useful for people with poor teeth who find chewing difficult.

So, by 'chewing' our food for us, blending can make things easier for our bodies. David Wolfe, 'Sunfood Diet Success System': 'Juicing and blending foods saves the body digestive energy channelling more energy for healing and detoxification.'

And anything that reduces the digestive burden must be good news. Victoria Boutenko in her book 'Green for Life' describes how many people over 40 have insufficient stomach acid (hydrochloric acid) necessary to rupture the tough cellulose structure of some raw fruits and vegetables and that low stomach acid in general means impaired absorption of nutrients. Not only does a smoothie help by liquidising tough leaves in the first place, but Victoria describes how in The Roseburg Experiment it was found that regular consumption of green smoothies was raised hydrochloric acid levels.

But not so good in others...

Although the blender can do the mechanical work of chewing for us, it can't do the chemical work. When we chew, enzymes in our saliva start to digest the food. And chewing makes our food more alkaline. Also, the very act of chewing sends signals for the release of digestive juices suited to the food eaten, and for enzymes to be released by the pancreas. The saliva itself helps relax the pylorus, a muscle at the lower end of the stomach that allows food to pass into the small intestine.

George Malkmus ('Hallelujah Diet') says that because the blended pulp and juice of a fruit in liquid form moves quickly to the stomach without the benefit of being pre-digested by the salivary enzymes, it 'becomes a difficult substance for the body to deal with' and that 'because of this, very few of the nutrients find their way to the cellular level of the body.' (bit of a downer!)

In an effort to compensate for the disadvantages of the blender bypassing chewing, some will tell you to 'chew' your smoothie. The word 'chew' is used simply to attract attention to the issue; it's not possible to chew a smoothie, as chewing is grinding solid matter between the teeth. But what we can do is swill it around the mouth, so that it's mixed with saliva before swallowing. This should help a little, although as David Wolfe believes we should chew our food 'around 50-100 chews per mouthful' (!), we're going to have to do a lot of swilling to match optimal chewing!

And there are other disadvantages of bypassing chewing. Some believe that many of our dental problems are due to eating soft, mushy food and that our jaws need grinding exercise to stay healthy just as the rest of our bodies need exercise. I've even heard that chewing helps strengthen our facial muscles and prevent jowls - how about that, 40-plusses?! But, OK - having said all this, most raw fooders will be doing a lot more chewing in their diets in general than cooked-food eaters, so this would only be a concern if smoothies formed a large part of our diets.


Once the food is in a liquid form it's much easier for us to ingest a lot of it.

Good in some ways

Victoria Boutenko advocates the eating of 1-2 lbs (500g-1kg) of green leaves per day. As not everyone enjoys eating this many leaves in leaf form, she recommends putting them into green smoothies (in which the leaves are often mixed with fruit).

But not so good in others

Some argue that, once raw for a while and more in touch with our bodies' needs, if we don't find eating 1-2 lbs (for supermarket shoppers that's 3-4 bags) of spinach leaves in one sitting appetitising in their natural state, then that's because our bodies don't (and shouldn't) need to eat that much.

Also, even if it's a food that we may be happy to eat a lot of in its natural state, turning it into a drink can still result in our ingesting too much too quickly. For example, I make around three glasses' worth of banana-date smoothie each morning, and, certainly before collating the material for this article, at times would gulp the whole lot down quickly and my stomach would hurt. Not good! Of course, this greedy style of eating also maximises the chances of our swallowing air, which can cause discomfort later.


Good in some ways

Depends on one's point of view...Some people like to blend the white part of a watermelon; others will blend carrot tops, or bitter leaves. The arguments for this are usually made from the nutritional standpoint, ie that these foods have been found to contain high levels of certain nutrients. There is also an economic argument in that parts of foods usually discarded are being used.

But not so good in others

What we're doing here is masking unpleasant tastes by combining the foods with more strongly-flavoured and/or sweet foods. We're effectively duping our tastebuds and in so doing bypassing the body's warning system, which is that if something doesn't taste good to us we shouldn't be eating it.

This is certainly one of my own reservations re the everything-but-the-kitchen-sink sort of smoothie - my policy is only to put into a smoothie something that I'd be happy to eat in its natural state. I don't find the white of a watermelon desirable, so would not put in my smoothie. Similarly, carrot tops don't taste good to me. To give an extreme example, an analysis of deadly nightshade might reveal very high levels of certain vitamins and minerals, but that doesn't mean we should be putting it into a smoothie.


I've been amazed at the number of ingredients some people use in their smoothies. Not only must it be impossible to taste some of the foods, but it would be all too easy to include digestively incompatible ingredients.

Slow-to-digest foods like nuts and seeds don't mix well with fruit. This is because the fruit wants to pass through quickly, and if its exit's blocked by heavier food, it will ferment as it hangs around, causing acidity and gas. I've had no problems with fruits mixed with almond milk, but perhaps that's because the almonds have been well-soaked first. But do be aware that fruit+fat is usually a no-no and be wary of tipping dry nuts/seeds into the jug along with fruit.

'Acidic' fruits such as orange and grapefruit (pineapple is also included in this category) should not be mixed with sweet fruits such as papaya, banana or mango. Although all fruits are alkaline after being metabolised, acid fruits need to undergo some change in the body before reaching this state. This involves some delay in the stomach, which holds up the passage of any accompanying sweet fruit. Again, fermentation is the result, and many raw fooders experience pain after such combinations.


Oxidases (oxidising enzymes) are released on the presence of oxygen and rapidly bring about a change in the colour of food (eg when apples are cut they go brown). Blending, as it pulverises the food and fills it with air, produces oxidisation - the amount of fizz and froth on top being an indication as to how much.

Dr Brian Clements (Hippocrates Institute) says that 85-92% of nutrients are lost through the heat and oxidisation of blending!

I'm puzzled by the reference to heat. It's true that the faster the blades and the longer the blending the more heat is produced. Indeed it's possible to bring a blend to boiling point after five minutes in a Vitamix blender. But most people don't blend smoothies for more than 20-30 seconds. I've touched the blades of mine after blending, and they've never been hot. Slightly warm maybe, but I'd say no warmer than body temperature.

Dr B's claim generated much discussion on international raw food forums. The research back-up for the statement did not appear to have been made available. And it would be interesting to see this, as surely level of nutrient loss would vary by the food being blended, and also by nutrient, and by how long after blending the smoothie was drunk. Many raw fooders (including some with scientific backgrounds) were unconvinced by this statement, but if anyone does have any of the scientific evidence for this (eg readings of various nutrients in x and y food prior and post blending) please let me know and I'll edit this article.

Victoria Boutenko, in her talk at The Raw Spirit Festival, reminded us that, if potatoes (you remember, in that 'past life'!) are submerged in water they don't go brown, and that consequently we can reduce oxidisation losses by using water in our smoothies. Although of course in blending we are introducing air into the mixture after it has has been mixed with water, I have heard from other sources that the water could still protect the food to some extent; in fact, this has been used as an argument to add water to thick mixtures to get blades moving rather than use the 'tamper' stick supplied with expensive blenders.

This could help: if you have a multi-speed blender, start blending at the lowest speed, thus minimising oxidisation and only blend at highest speed if necessary, and then only for a few seconds.

Also, I would have thought that, as sprinkling lemon or lime juice on food lessens discolouration, adding the same to our smoothies could make sense.

And of course drink your smoothie immediately to avoid further oxidisation from contact with air. As you know, a banana smoothie will change colour quite quickly if left undrunk. However, my feeling is that storing undrunk smoothie in the fridge, or taking it to work, is fine. I'll go out on a limb and say that, although Dr B is a biochemist, and OK I'm definitely not, I'm not convinced by his figures, and still reckon that, although drinking a smoothie immediately is optimal, there'll still be plenty of goodness left if you finish it later on.


Unless you're like my husband, who won't drink smoothies because he doesn't like the consistency, you probably enjoy smoothies, as I do. They taste so good, and are so easy to make! And in that respect, if those two things alone help people stay raw, smoothies are good news! In fact, I know a raw fooder who pretty much came to raw through smoothies.

For me...daily smoothie? Yes, definitely.

Nothing but smoothies for days/weeks? 'Smoothie Feast?' No. (What do you think?)

If, like me, you're going to continue to make and enjoy smoothies, here's a list of things I suggest we can do to maximise the benefits and minimise any disadvantages.
  • Don't mix acidic fruit with sweet fruit.

  • Include water.

  • Use blender on lowest speed first, and minimise time at high speed.

  • Ideally, drink the smoothie just after makingit.

  • Sip it slowly, and swill around the mouth.

And if you've never tried a 'green smoothie', I recommend Victoria Boutenko's book 'Green for Life' for the rationale. And you might like to try one of these combinations:

spinach and mango, kale and pineapple, lettuce and banana

In each case, blend the fruit component first. Then add leaves to taste (pushing them down into the blended fruit), along with water.

The 'spinach and mango' in particular is a great one to make when non-raw people are around. After perhaps an initial 'what on earth is that?', if they can be persuaded to try it chances are they'll be pleasantly surprised!



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Jessica Loyer said...

Thanks for putting all of this information together in such a clear, thorough manner. I agree that the raw food world is cluttered with conflicting information and mis-information. Thanks for providing some insight into this particular debate.

I agree with you conclusion, as well. I THRIVE on my morning green smoothie. If I have something else for breakfast even for one day, I feel sluggish and uninspired all morning, whereas if I have my green smoothie I am positively brimming with energy and enthusiasm. However, I rarely desire more than one smoothie per day. Usually by afternoon I feel pretty hungry and a strong desire to chew.

Your blog is fantastic. Keep shedding and shining your raw light!

Debbie Took said...

Well, thank you 'raw gastronome'!

(What a great name - do let us know if you have a blog or website.)

Jessica Loyer said...

Glad you like the name!

My blog is Do visit.

Xerxes said...

Excellent post as always Debbie!


Mila said...

i have to say,,,,,i still love my smoothies...but, i am going to forego the ice...
for me, BALANCE is key. if i start to get to 'obsessed' with getting this raw vegan thing 'perfect' it does more harm than good.
for me, i believe in the 'everything in moderation'...
but, as always, insightful arguement

Unknown said...

In a world where everyone dies and where most people are dying from lack of nutrition either through poverty or ignorance, it seems rather crazy that people are worried about losing a small percentage of nutrients by blending incorrectly or leaving it in the fridge too long. Any raw fruit and greens smoothie that you do is a million times better than a Big Mac in every way possible, so blend away to your heart's content. I often make them very watery and have them as a drink to get that extra water in.

Debbie Took said...

OK, take your point to some extent, but I don't think it's 'crazy'.

Raw fooders are unlikely to be losing sleep over this, but if people are going to drink smoothies daily, they might as well get the most out of them!

(I think any discussion on any subject of interest only to a small percentage of people, eg tropical fish-keeping, weight training etc, would seem trivial compared with the issues faced by the world in general :-))

Unknown said...

Yes, you are right, 'crazy' was a crazy word to use there.
Any tips for reducing air bubbles?
SO far I pour small amounts into a jug and swirl it around before pouring it into the pint glass. It's a little more work but it gets a lot of it out.
Is there another way?

Debbie Took said...

Aha - now air bubbles is not something I've really thought about :-) The only thing I can suggest is blend more gently, ie at a low speed for longer?

Jim said...

Hi Debbie. What a great article. You really explained all the factors of blending really well!

James Reno

Debbie Took said...

Thank you, James!

And I'm off to have a look at your site - love the name!

Janine said...

Hi Debbie, I was wondering is cabbage ok to add to a fruit smoothie with something like bananas and dates? I've been doing this and they taste lovely.

Debbie Took said...

Hi Janine

I think, if it tastes good, and your tummy feels OK afterwards, ie not 'windy', the combination is fine!

Elizabeth said...

I just started my raw food diet yesterday- juicing and eating the tomatoe pasta and fruit.

I am 220 pounds because of my horrible diet of meat and carbs. I have a very severe mental illness - schizoaffective disorder, which I take supplements for through orthomolecular doctor to fix deficiencies. I pay way too much money for these 300 a month. I am fed up with this pill regiment and i'm hoping to be able to cut down by changing to a raw food diet. I saw on youtube, a woman who lost over 100 pounds and her schizophrenia by eating raw. So far, I noticed my sleep last night was so deep and my sex drive is coming back. The pharmaceuticals I was on before destroyed my body and made me prediabetic with high cholesterol. I am hoping to reverse the damage. The scary thing is that people with my illness die 25 years younger than the rest of the population because of higher rates of obesity and smoking. I gave up smoking 11 years ago. I hope I can add more years onto my life and not die a horrible death from cancer. Thank you all for posting your information to help people like me.

Anonymous said...

I thoroughly enjoyed this article, and I appreciate you taking the time to write it! I came to raw foods to heal an autoimmune disease that causes my muscles to get severely fatigued with use (Myasthenia Gravis) so you can imagine how hard it has been to CHEW all these raw crunchy foods! Needless to say I got down to 100lbs (I'm 5'6"!) and realized I was only averaging about 500 calories a day... Which led me to take a better look at my VitaMix. "Can you help me get mass more raw nutrition?" I asked. "You know I can!" it replied. So I am doing a test of 40 days (about six weeks) to see how my body feels eating mostly blended foods (3 out of 4 meals each day) -- because in my particular case, it may just be the perfect thing!

Debbie Took said...

Hi Meg Thank you so much for the feedback. The Vitamix is indeed a wonderful thing! Mine's been used almost every day for about seven years now and is still going strong.