Superfoods: How to get the best nutrients out of your fruit and vegetables

by Nicky Pellegrino / 28 October, 2017
RelatedArticlesModule - Superfoods

Photo/Getty Images/Listener illustration

The new king of superfoods, James Wong, says he’s not peddling faddism, but revealing the basic science tricks of how to get the best nutrients out of vegetables.

Just because food is processed doesn’t mean it’s bad for you. Some vegetables are healthier if treated roughly. The peelings we’re chucking out are better for us than the bits we’re eating. Not all apples are created equal.

Those are just some of the messages from the new king of superfoods, James Wong. And if seeing that buzzword has you assuming this is going to be yet another story urging you to double your grocery bill by investing in a trolley-load of on-trend goji berries, chia seeds and maca-root powder from the Peruvian highlands, then don’t worry. Wong’s point of difference is that he believes any food, from the humblest kumara to the cheapest cabbage, can have its nutrient value supercharged. It all comes down to the way you select, store and prepare it.

London-based Wong is an ethnobotanist rather than a dietitian, so his focus is on plants and how we use them. He trained at Kew Gardens and has since carved a niche as one of those scientists who specialises in presenting the latest research to the public in friendly and accessible ways – he calls it “decoding geek-speak”. On the BBC television show The Secrets of Your Food (which he co-presents with veteran broadcaster Michael Mosley), on radio and in gardening books, the personable and enthusiastic Wong has steadily built a profile.

The inspiration for his latest book, How To Eat Better, came while he was in Japan. “I met a woman who said she was a fruit and vegetable sommelier,” he explains. “There are thousands of them there and she was surprised when I needed her to explain what she did.”

James Wong with Michael Mosley, his co-host on the BBC television series The Secrets of Your Food.

Fruit and vegetable sommeliers, certified by the Japan Vegetable Sommelier Association, advise the public and institutions on the selection, storage, preparation and nutritional value of produce. Some high-end restaurants and hotels hire them to collaborate on menus. It may sound wacky but, as Wong points out, “we have someone who advises on how to pair gone-off grape juice with food and we think that’s a job.”

Intrigued, he took a closer look at the science of produce to find out if we could increase the nutrition we get from everyday foods. He spent two years poring over every piece of research he could lay his hands on.

“For every 10 papers I’d read, maybe one would yield a fact that was relevant,” he says. “Most trials aren’t done for domestic situations, but I was surprised at how much research is out there and how much is applicable.”

Photo/Getty Images


In a world overrun with Instagram-friendly wellness “influencers” spouting pseudo-science, Wong’s approach is refreshingly evidence-based and user-friendly. A self-confessed lazy cook, with an eye for the best price, he’s not about advising readers to invest in fancy equipment (“I’m never going to get a spiraliser out to do anything,” he promises), long hours or pricey ingredients.

“I really object to the notion that food must be expensive to be good for you,” says Wong. “It puts people off healthy eating. On social media, people will tell me they can’t afford to eat well. But a can of tomatoes is no more expensive than a can of Coke and no one would say they can’t afford that.”

The cooking and processing of tomatoes increases the amount of the phytonutrient lycopene that the body is able to absorb from them. This antioxidant is believed to be beneficial in preventing disease, including some cancers (in particular prostate), and lowering the risk of stroke.

Photo/Getty Images

“Apparently, a lot of people already knew that, but I didn’t. I also didn’t know that adding olive oil helps [with absorption of lycopene] and I’d never heard about storing tomatoes out of the fridge from anyone but my mother, and she couldn’t tell me why (lycopene levels increase when they’re kept at room temperature). So now my tomatoes are on the counter and I eat them cooked as well as raw. It’s nice to know tinned tomatoes are just as good, because they are affordable and convenient.”

The variety of tomato you choose makes a difference, too. Since lycopene is more concentrated in the skin than in the pulp, it’s worth going for cherry tomatoes and baby plum tomatoes, which have more skin surface area than the big beefsteaks.

Wong has similar tips for just about every common fruit and vegetable you can think of. Buying mushrooms? Portobellos are high in an immune-boosting substance called chitin and brown button mushrooms score highly for polyphenols (micronutrients that have antioxidant properties). Store any old mushroom on a sunny window ledge for a couple of hours and its vitamin D levels will rocket because they have a very similar reaction to the one that happens in human skin when exposed to sunlight.

Photo/Getty Images

“In the supermarkets here, you can buy UV-treated mushrooms,” says Wong. “They’re put on a conveyor belt and exposed to light for a few seconds. I was wondering about doing the same thing at home and thinking about getting out my grow lights, but then it occurred to me that you could just do it on the windowsill.”

And then there is broccoli. It contains a compound called glucoraphanin that has been associated with reducing the risk of heart disease, cancer and diabetes. Broccolini has even more of it than broccoli, and it pays to eat it while it’s still fresh or to store it in a sealed bag in the fridge.

When the broccoli is harvested, it releases a compound called myrosinase, which reacts with the glucoraphanin to produce a group of chemicals called isothioacyanates and these are believed to be behind many of the cruciferous vegetable’s health benefits. Cooking broccoli stops that all-important chemical reaction in its tracks – and, really, who wants to eat the stuff raw?

But in 2012, a team from the University of Reading were able to restore cooked broccoli’s ability to generate isothioacyanates by adding a small amount of powdered mustard seeds. So his advice is to eat broccoli with a mustard-based dressing (the same enzyme is found in wasabi and horseradish).

Photo/Getty Images

Living food

“Most people think of fruit and veg as not living,” says Wong. “They assume that once you’ve picked it, nothing is going to change. But in the fruit and vegetable aisle, they’re still living plants.”

So, “wounding” your vegetables – slicing cabbage into a slaw, grating carrots, tearing lettuce – stimulates their pest-fighting response and sends levels of beneficial compounds soaring.

Some veges, such as leafy greens, are best eaten fresh, but others benefit from storage, Wong says. Winter squash and pumpkin develop higher levels of carotenes (vital for eye health) for a couple of months after they’ve been picked. He urges everyone to eat the skins to benefit from five times more carotene than the flesh; to choose crown pumpkin over butternut squash as that variety contains more of the antioxidant; and to roast rather than boil it, as some of the goodness leaches into cooking water.

Photo/Getty Images

Small things can make a difference to how much nutritive power a plant has. Outdoor tomatoes planted in a sunny area are going to have more lycopene than those raised under cloudier skies. Even the position of fruit on a tree can be significant: the apples growing at the top will get the most sunshine.

Wong says there is some truth in the popular notion that modern, high-yield varieties and over-cultivated soils result in crops that are less nutritious.

“There is some good research that indicates this may be the case for some nutrients – but not all nutrients and not all crops,” he says. “The upside is that modern agriculture has increased productivity so fruit and vegetables are much cheaper and we’re able to eat more of them.”

He isn’t buying into the romantic idea that food was better in the past. “We live in a time when we have more plentiful food options available to us than ever. We’re just not necessarily taking [advantage of] them.”

James Wong. Photo/Jason Ingram

Pesticide anxiety

He is also a calm voice when it comes to pesticides. “A lot of people say they always peel fruit to get rid of the pesticides, but the risk associated with them is tiny compared with the benefits you get from the phytonutrients in the peel.”

Wong’s is just one voice in a chorus of experts offering dietary advice, much of it contradictory. He is well aware of the confusion surrounding what constitutes healthy eating.

“There is a lot of conflicting information,” he says. “But one of the things I have a bee in my bonnet about is that it doesn’t come from science; it comes from the reporting of it. Sometimes you’ll see contradictory headlines in the same newspaper within a couple of weeks. That’s not underpinned by science but the need to sell newspapers with a ‘surprising truth’ story.

“As a result, I think there’s a whole generation becoming cynical and distrusting of science. They think we change our minds all the time, but fundamentally we don’t unless we find new evidence.

Photo/Getty Images

“The problem is a lot of people think science is a chain and the latest study is the endgame. But there are hundreds of studies churned out all the time and you’ll find one to prove pretty much anything. What we need to look at is not a single study but a body of evidence. That’s why science is hard. We like simple answers for things, but the world is too complex and beautiful for that.”

An example of oversimplification is the practice of using “processed” as a byword for bad. “In many instances, processing is wonderful. Chewing is a process. Cooking is a process. People take an umbrella term and go wild with it,” says Wong. “Recently I was in a health-food supermarket and saw a sign that read: ‘Say no to sugars and processed food’. But the fruit and vegetable aisle in that store is tiny. Most of it is filled with goji berry chia granola – things in packets.”

Processed beetroot, pre-cooked and vacuum-packed, has been shown to have not only more antioxidant capacity than raw beetroot, but also potentially more heart-healthy betalains – the pigments that make the flesh red – than home-cooked beets. Instant coffee still contains heart-healthy polyphenols but not the natural substances believed to raise cholesterol that you’ll be drinking in your espresso. And enjoy expensive freshly squeezed orange juice? You may as well swap it for a cheaper brand that’s made by blitzing the whole orange and filtering off the pulp because during this process – known as comminuting – nutrients from the zest and skin leach into the drink, boosting levels of anti-inflammatory flavones.

Photo/Getty Images

Against fetishism

Wong is not against fresh food – his new book is full of simple, healthy ways to prepare it – but he isn’t fond of the fetishism that goes along with healthy eating.

“Somehow a goji berry has miraculous powers,” he says. “I grew up in Singapore with a Malaysian-Chinese father. We ate them like raisins and they cost about the same.”

Science and good sense go hand-in-hand for Wong, which is why he’s finding healthy ways to put carbohydrates back on the menu. Cutting them out is impractical both for people’s budgets and also for the planet. “Carbs create the largest amount of calories per square metre of land or per unit of water,” he points out.

Worried about your blood sugar? Black and red rice have a lower glycaemic index (GI) and so won’t spike it as much as white rice does, and those rices pack in more polyphenols – more than blueberries, which are traditionally touted as a food superstar.

And don’t give up on potatoes. Rather, instead of the floury mashing variety, go for small, waxy new spuds that have more phytonutrients (eat the skins), and less effect on blood sugar.

“I find the floury ones a bit like eating talcum powder,” says Wong, though he deals with that by adding a lot of cheese or butter.

Photo/Getty Images

Super wine

Wong loves to eat, and none of his suggested switches is likely leave even the keenest foodie feeling deprived. And if you fancy a glass of wine with all those supercharged veges, have two. But go for a red, preferably a dark, full varietal such as syrah, grown in a hot region such as Australia rather than a cool one (such as New Zealand, unfortunately) and you’ll be sipping more anthocyanins – the red-pigmented polyphenols. Just remember that if it has been aged, no matter what a wine sommelier might advise, those flavonoids start declining.

Purple and red

In general, purple and red are the colours to be looking for in plant foods: purple carrots rather than orange; purple kumara or cauliflower instead of white; red capsicum not green; dark-red morello cherries rather than those pretty yellow ones. The same goes for apples – braeburn and red delicious outrank granny smiths.

Following Wong’s compendium of clever tricks may have pay-offs, from slowing age-related memory decline to lowering blood pressure and decreasing the risk of all the lifestyle-related killers – heart disease, cancer and stroke. Not that he’s expecting you to remember every antioxidant-rich gem of information.

“The more tips you follow, the more benefit you’ll get,” he says. “But at the end of the day, the healthiest vegetable is the one you’re likeliest to eat.”

Photo/Jason Ingram

Photo/Jason Ingram

Do try this at home: Recipes from How To Eat Better

Roast asparagus & salmon with herb mayo

Bung a bunch of things in a tin and bake it. Get a complete (and uber-healthy) meal in about 30 minutes. That’s my kind of cooking.

1 tsp horseradish

2 garlic cloves, crushed

2 tbsp olive oil

finely grated zest of 1 lemon

4 salmon steaks, about 150g each

400g asparagus

1 lemon, sliced

400g cherry tomatoes

salt and pepper


4 tbsp mayonnaise

1 tbsp milk

1 tbsp chopped dill

1 tsp chopped parsley

3 spring onions, chopped


1 large bunch of watercress

lemon wedges

Preheat the oven to 200°C. Mix the horseradish, garlic, olive oil and lemon zest together in a small bowl. Lay the salmon steaks in the centre of a large baking sheet with the asparagus, lemon slices and tomatoes. Brush the salmon and vegetables with the oil mixture and season well. Bake for 15-20 minutes, or until the fish is cooked through and the asparagus is tender.

Meanwhile, blitz all the mayo ingredients in a food processor until smooth. Divide the salmon and vegetables among 4 serving plates, then add a small bunch of watercress and a dollop of mayo to each one. Serve with lemon wedges for squeezing over.

Serves 4

Singapore green banana curry

This is my shamelessly Westernised take on my favourite curry, which they used to serve on Tuesdays at my school canteen in Singapore. Warming and creamy, this is comfort food, South-east-Asian style.

4 green bananas

1 tbsp olive oil

1 onion, finely sliced

3 tbsp red curry paste

1 tsp turmeric

400ml coconut milk

1 red capsicum, cored, seeded and sliced

100g green beans, trimmed and sliced into 2.5cm pieces

1 garlic clove, minced

1 tsp peeled and minced fresh root ginger

salt and pepper


3 red chillies, sliced

25g coriander or mint leaves, shredded

50g toasted flaked almonds

Peel the bananas with a sharp knife (this isn’t as easy as it is with ripe ones), then slice into 1cm discs. Heat the oil in a large saucepan, then add the onion and fry over a medium heat for about 5 minutes until soft. Add the bananas, curry paste and turmeric, then fry for another minute or so until fragrant.

Pour in the coconut milk and bring to the boil, then stir in the capsicum, beans, garlic and ginger, cover and simmer for 5 minutes. Season to taste with salt and pepper. Divide the curry among 4 serving bowls and serve sprinkled with chilli, coriander or mint, and almonds.

Serves 4

HOW TO EAT BETTER, by James Wong (Hachette $39.99)

This article was first published in the September 30, 2017 issue of the New Zealand Listener.


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