Walk round a market in Sicily or Crete and you'll notice something before you notice anything else: the colour. Purple aubergines stacked next to blood-red tomatoes, orange peppers, bunches of dark green herbs tied with string. Nobody's arranged it to look nice: it just happens, because that's what a genuinely varied diet looks like when you pile it on a table.
That's not a coincidence, and it's not just about presentation either. Colour turns out to be one of the more useful, low-effort signals we have for whether a diet is actually doing much for us - and it's a big part of why the Mediterranean way of eating keeps coming up in research on brain health, eyesight, and healthy ageing generally.
Where does the colour actually come from?
Plants aren't colourful for our benefit. The pigments are there because the plant needs them - to fend off insects, to survive being a plant rooted in one spot with no ability to run from a problem like excess UV light. Chemically, most of these pigments belong to a huge family called polyphenols, and there are thousands of them.
The useful bit, for us, is that eating those pigments seems to bring some of their protective effects along with them. Once inside the body they tend to behave as antioxidants and anti-inflammatories, mopping up some of the damage that builds up over time and contributes to a long list of chronic diseases.
And here's the thing that matters most: no two colours contain quite the same set of them. Which is really the whole argument for why variety counts for more than people give it credit for.
A rough guide to the colours
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Red - tomatoes, watermelon, red peppers. Mostly lycopene and anthocyanins, both tied to a lower risk of heart disease and, for lycopene specifically, some cancers.
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Orange and yellow - carrots, squash, mango. Beta-carotene territory, good for immune function and eyesight.
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Green - spinach, kale, broccoli. Chlorophyll and lutein mainly, plus compounds that support the body's detox pathways.
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Blue and purple - blueberries, aubergine, red cabbage. Anthocyanins again, this time with a fair bit of research behind them for memory and cognitive function.
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White, brown, tan - onions, garlic, wholegrains. Easy to forget about, but they bring allicin and flavonoids that do a lot for the gut and the heart.
It's the mix that makes all the difference - which is largely why the Mediterranean diet built around a wide spread of vegetables, fruit and herbs rather than the same two or three "safe" choices on rotation.
Variety over volume
Most advice still centres on quantity - five a day, and so on. But there's a growing pile of research suggesting the number of different plants you eat might matter just as much as how much of them you eat.
A 2023 meta-analysis of observational studies found that people eating a wider variety of fruit and veg had a lower risk of cardiovascular disease and death from any cause - and this held up independently of how much they were actually eating.
A separate study that followed a Mediterranean population for eighteen years found much the same thing: higher dietary diversity, lower all-cause mortality.
Then there's the gut angle. The American Gut Project - one of the biggest citizen-science microbiome studies ever done - found that people eating more than thirty different plant foods a week had noticeably richer, more diverse gut microbiomes than people eating ten or fewer. More diversity down there will usually track with a stronger immune system and better metabolic health generally.
So "eat the rainbow" isn't just a nice bit of marketing: it's shorthand for something the research keeps landing on.
So how colourful does a plate need to be?
You don't need to count anthocyanins or work out which vegetable does what. Two or three colours per meal is a decent working target, and swapping things around across the week - rather than buying the same broccoli and carrots on autopilot - does most of the heavy lifting. Frozen and tinned veg still count. So do herbs, spices, and the bits people usually bin like potato skins or cauliflower leaves.
It's basically what the Mediterranean diet does without anyone having to think about it too hard. Not a rulebook, just an eating pattern that ends up colourful because that's what a plate full of different vegetables, fruit, olive oil and herbs looks like by default.
Next time dinner looks a bit beige, it's worth asking whether it needs a bit more colour on it - not because it needs to look better, but because it probably needs to do a bit more.
Part of a Series
This article is part of series on staying healthy as you get older and improving your quality of life.
It’s not only a goal almost everyone shares, but has huge implications on national healthcare spending, productivity and economic resilience.
It strongly recommends the Mediterranean diet as the best way of eating but recognises that maintaining strength and aerobic fitness is also a critical part of a healthy ageing lifestyle.
It also suggests a supplement to help reach the increased plant nutrient/polyphenol levels that you need as you get older.
DailyColours® contains 161 plant nutrients – nutrients that are missing from an ordinary vitamin and mineral pill. Clinical trials show that it offers Mediterranean diet benefits in a daily supplement. You can see it here.
Note: The content on this site is intended for general wellness and informational purposes only. It is not personalized medical advice. Consult a healthcare professional before making any changes to your diet, exercise, or lifestyle routines.