A basket of colourful phytonutrient-rich produce picked early in the morning from my polytunnel
Since I first began growing organic vegetables for my family over forty years ago - the question of exactly when is the best time of day to harvest those vegetables is also something which has always interested me. If we go to the trouble of growing our own vegetables and fruits - then we naturally want them not just to stay fresh for the longest possible time but also want to maximise their healthy nutrient content. Whether we grow a lot of veg outdoors, are lucky enough to have a polytunnel, or even if we just have a couple of containers by the back door or window-box with some fresh salad leaves - it's important to know how to get the maximum health benefits from your precious hard-won produce by harvesting it at exactly the right time. Science is still a very long way from understanding precisely how everything in soil works and what contributes to manufacturing plant nutrients - but we do know that it all evolved to work together in a natural synergy. That being so - there is no doubt that organic produce is going to be highest in healthy nutrients - whatever some of the arrogant pro-pesticide pro-GMO lobby may say! I'm not just talking here about the outdated concept of so-called "essential nutrients" as we currently classify them (which I'll talk about later) and which the non-organic lobby use for comparison. I'm also talking about the phytonutrients that Nature evolved over millions of years, as it clearly decided that they were necessary for our health too!
I've always felt that the key to growing any plant really well is to take the trouble to understand exactly the right conditions it needs, in order for it to grow as healthily as possible. Healthy plants don't get pests and diseases as their immune systems are working properly. This means we need to understand the ecology of each particular plant and study how it grows in it's natural environment. That applies to all plants - not just food plants. If you've been a reader of my blog for a while, you'll know that as well as being an organic gardener and former commercial grower, I'm also a keen amateur botanist and lover of unusual plants, especially food plants! I've also always had a special interest in eating a healthy, pesticide-free organic diet, as rich as possible in all the healing antioxidant powers of plant phytochemicals. This interest was sparked by one of my childrens' very severe health problems when young. As a result I've been a keen reader of science articles for the last 40 years and I've often come across some quite quirky pieces of information about plants that fascinate or amaze me. I'm constantly in awe of the many things that plants are able to do in order to survive. Recently - many new and astonishing aspects of how they react to their environment have been revealed, thanks to the wonders of modern electron microscopy. Not necessarily what might be of interest to your average supermarket shopper perhaps - but it's definitely of interest to those who want to get the most nutrients possible from their diet!
The question of exactly what time of day crops are the highest in all their nutrients is a very interesting one. Most of us probably know that early morning when it's cool is the best time to harvest most things, before they get warmed by the sun and start to wilt - possibly losing nutrients. A couple of years ago I came across a particularly fascinating little nugget of information. Contrary to what many people think - plants were designed by nature as modular systems - rather like Lego! This means that each part of a plant can potentially survive to become a new plant given the right conditions. This is why we can take cuttings of shoots, or use tissue culture to make new plants identical to the parent. It also means that each part of the plant goes on functioning as normal for quite some time after being severed from the parent plant, in exactly the same way as the rest of that original plant! In other words - it can perform all the biological functions of the original plant. And this is where the really interesting bit is - from a healthy eating perspective.
To set the scene - plants have all the senses that we have - they just happen use them differently. Like so many things that some of our sometimes arrogant species thought we already knew everything about - when trying to understand plants our perception of them is a big drawback for us. As humans, we tend to only class things as intelligent if they behave and react to outside stimuli in exactly the same ways that we do and that we can understand. We assumed until very recently that plants are only green things - sometimes edible - that sit there and well - vegetate! We couldn't be more wrong! Exactly like us - every cell in their bodies is constantly busy doing all the things it needs to do in order to survive. They can feel, hear, react to sounds and scents, move (roots permitting) and also sense light - and this is the attribute I'll explain the importance of later! Amazingly - they can even perform complicated arithmetic! In the evening - they accurately calculate the amount of energy-giving carbohydrate stores they have and divide it up into hourly portions, so that they have enough energy to function normally during the night - when they can't make energy from photosynthesis using daylight.
One vitally important aspect of plant nutrients from our point of view is that because they obviously can't run away like us - over billions of years plants have also developed an amazing array of natural weapons which they can use when something attacks them. These are the plant compounds that we call phytochemicals. They are Nature's pesticides if you like! The important thing to understand though, is that unlike synthetic man-made pesticides, we evolved to eat them as phytonutrients - so they're clearly beneficial for us too! They are powerful natural chemicals that can have enormous health benefits for us when we eat them. Although not currently classified as "essential nutrients" which are necessary purely just to keep us alive - meaning water, vitamins, some minerals and amino acids(proteins) - nevertheless science is increasingly beginning to recognise that phytonutrients are essential to keeping us alive healthily! Just as in plants - they are a vital tool in our bodies disease-prevention armoury too. Our ancestors have been eating them for millions of years and the cells in our bodies have evolved to recognise them and use their powerful antioxidant properties at a genetic level, to reverse DNA damage caused by toxins in our environment and to prevent disease. What I find fascinating is that many other organisms seemingly quite distant from us in evolutionary terms also use these same compounds in exactly the same basic metabolic way - this why scientists can use a type of worm or fruit flies to research how phytochemicals affect us. So that makes me think that Nature clearly decided they were essential nutrients - because Nature never wastes a thing! It works on the old adage - if it ain't broke - don't fix it! If a function is necessary for successful life - then it retains it and builds on it to make another, even more complicated organism and so on, ad infinitum. Just like my Lego analogy earlier! That's how we evolved from simple bacteria to us!
Science is now beginning to prove daily just how significant they are and we are only just beginning to see the tip of the iceberg! There are thousands more phytochemicals as yet still undiscovered, which all work together in different synergistic combinations complementing each other. That's why every nutrient is precious and is why it's so important to eat as varied a diet of whole fruits and vegetables as possible and to eat them in the original combinations which nature designed - not try to target individual compounds and take them as probably unbalanced or possibly even dangerous supplements. They are very powerful chemicals even if they are natural - and when it comes to most supplements - once again man is blundering blindly about just guessing! I am personally of the opinion that the old fashioned concept of 'essential nutrients' will soon start to become just as obsolete as the ludicrous idea that processed synthetic fats are better than natural fats! If phytochemicals weren't essential to our health - then would our gut bacteria have evolved to deal with them, or our genes to recognise and utilise them? I'd dearly love to live another lifetime to see what happens when scientists and doctors finally accept how beautifully and completely everything is connected, to understand exactly how to use naturally-grown, organic 'real food' as medicine - and to understand that the answer really does "lie in the soil" to use that well-worn expression! That will truly be going 'back to the future' when doctors finally accept that Hippocrates was right all along when he said "Let food be your medicine and let medicine be your food".
Am I straying away from my original subject? No - I was just setting the scene for the real nugget that I want to share with you! Whether you grow your own vegetables or if you buy them - the most important thing you need to know about maximising nutrients, first and foremost, is that they also have a circadian clock exactly like we do. This means they have light-sensitive cells in every part of the plant which tell them whether it's day or night! That light-sensitivity governs their internal circadian clock and all the biological functions which they perform at particular times of day or night. This works in exactly the same way that our circadian clock governs our bodies. As a result - plants have a constant awareness of what time of day it is, just from sensing light. In other words - plants can tell the time - probably a lot more accurately than we can! Because of this ability - plants don't waste precious energy on producing their protective phytochemicals during the night. They start to step up production of them a couple of hours before dawn - in anticipation of attacks by the hungry hordes of insects which will descend on them at daybreak for breakfast! That way the plants hope to repel them either by a nasty taste or unpleasant smell! How clever plants are and how beautifully Nature designed everything!
This leads me back to my original question "When is the best time to harvest veget
But what if you're buying vegetables? Are they really more nutritious if local, seasonal and organic?
Have you ever suffered from jet lag? Did it ever occur to you that perhaps vegetables and fruits might do too? Daft? No! Sorry to the nay-sayers who again make fun of those us who say that we think local seasonal and organic is best! But once again - timing is everything! There is now finally proof that they are indeed more nutritious - and I'll tell you why! This is aother really interesting point that follows on from the discovery that plants have circadian clocks. Naturally, the circadian clocks of all vegetables and fruits are synchronised to whatever part of the world they happen to be growing in - since their survival totally depends on it. They are living things after all - and all life on earth is governed by the basic circadian rhythms of day and night - even the simplest bacteria and algae. Only common sense really isn't it? Why did no-one ever think of that before, since they have all the basic senses that we have - but just use them in a very different way!
So why is this relevant to nutrient content of imported produce? Well - researchers have recently discovered that if the synchronicity of their circadian clock - or day/night pattern is disrupted - then just like us, the daily rhythms and biological functions of plants are also disrupted. Add to this perhaps travelling half-way across the world in dark containers, being held for some time in a distribution centre before delivery and after that being stored on a supermarket shelf in constant light - is it any wonder they become disoriented, confused and quite literally 'jet-lagged'! They then start to gradually lose their ability to protect themselves by producing the phytochemicals which are their immune system.
Interestingly, the scientists doing the research also found that just as our internal clocks can gradually be 'entrained' or re-adjusted so that we can function normally again, it is possible to do this in plants too. The problem is that it can take 3 days or more for their internal clocks to re-adjust, by which time many other nutrients such as vitamins will already have started to deteriorate. The losses of vitamins may be less it they're kept at around 4 degrees C in a fridge - but again any fridge will be dark once the door's closed - so they still won't know whether it's day or night. That means their phytochemical production slows down even more because they need light to know when they're supposed to produce them. They also start to gradually lose their source of the stored energy they need to produce them! Alternatively, if they're kept in constant light they will quickly become exhausted from overproduction of phytochemicals and lack of energy, just as you or I would if not allowed to sleep after travelling a long distance! That's a form of torture for humans and probably any other living organism. Anthropomorphising vegetables? No! This is all actually of great interest to scientists who are now looking to improve the storage of vegetables and possibly enhance their phytochemical production, by manipulating the amount and timing of the light which they are exposed to.
So in the meantime - I think it's pretty clear to anyone unbiased that local, seasonal and naturally of course, organic, really is better for our health after all!
You may have read some of this article before, as I first published it in early 2015.
I thought that it was time to update it now for two reasons. The first reason is that since then, a lot more fascinating information has been discovered about the plants which we depend on for our survival and how their microbiome - or phytobiome as it's known - interacts with their environment. More is being discovered daily, through the wonders of modern microscopy. If you have any interest in food or plants - this is such an exciting time to be alive with new things being discovered literally every day!
The second reason is that I'm heartily sick of some so-called 'experts' and a headline-hungry media, who often seem to love nothing better than to use their high profile or wide circulation to ridicule advocates of organic, local and seasonal, in a cheap and cynical effort to boost their popularity or readership. Their misinformation is literally affecting people's health! Some of this is naturally led by the PR propaganda of the agricultural pesticide industry, who are getting increasingly worried that their profits and share prices may soon drop!
The older-style 'experts' I actually had a little more respect for - despite their mistaken belief that chemicals were the great new world. At least they were genuinely-held beliefs and many had experienced the difficult conditions of WW2 rationing, with all of it's shortages. They had also been thoroughly indoctrinated in 1950's agricultural colleges. The newer breed of 'experts' however are a different proposition and far more clever. Frankly - they are despicable! They don't operate on the basis of genuinely held beliefs - but are driven purely by popularity ratings and money - and they don't give a damn who or what gets damaged in the process! Yes I am angry - but with good cause! I care about my children's future and hopefully their children's future too. I care about the future of what's left of Nature on this beautiful planet that we all live on. I've seen so much of it tragically destroyed unnecessarily with my own eyes during my lifetime!
As I mentioned earlier - there are now a growing number of studies showing that organic is better from every possible point of view. Not surprising since that's the way Nature's always done it! But the 'experts' tend to cherry pick and repeat parrot-fashion the old "essential nutrient" / vitamin and mineral data which are pretty much on a par between organic and non-organic. They also repeat that old mantra - "organics won't feed the world" - now thoroughly discounted! You don't need a degree or to be a scientist to know that. As my scientist son says - you just need to be able to read! It suits the purposes of those cynical 'experts' to ignore the other reasons why organic is better from every point of view. More phytonutrients, fewer pesticide, antibiotic and heavy metal residues, antibiotic resistance, animal welfare, soil health, environmental issues, climate change.....etc. etc...I could go on - but there's another article in that lot! Watch this space!
Study on how plant circadian clock affects their metabolism: http://www.cell.com/current-b
(Please note. I really enjoy sharing my original ideas and 40 years experience of growing and cooking my own organic food with you. It's most satisfying and naturally also very complimentary if others find "inspiration" in my work......But if you do happen to copy any of my material, or repeat it in any way online - I would appreciate it very much if you would please mention that it originally came from me. It's the result of many years of hard work and often hard won-experience. Thank you.)