In a world filled with choice, I have sought comfort in the reassurance of simple food decisions. The same office lunch nearly every day of an M&S mozzarella-and-sundried-tomato wrap followed by a reliably delicious gooseberry fool yoghurt. Or a homemade lunch featuring the usual roasted veg suspects, accompanied by halloumi and couscous.
It's not that I don't have an adventurous palate, but rather that I am time-poor and information-overwhelmed. I easily make my five a day, but it's generally from the same cast of characters. If I buy a cauliflower, then that's the central performer of my cooking week. Next week butternut squash might be in the starring role.
The five-a-day campaign – which was adopted in 2003 by the UK government – is based on advice from the World Health Organisation, which recommends eating a minimum of 400g of fruit and vegetables a day to lower the risk of serious health problems, such as heart disease, stroke and some types of cancer. However there's a new mantra on the chopping board: 30 a week.
Scientists such as the epidemiologist and nutrition expert Professor Tim Spector and Dr Megan Rossi, aka The Gut Health Doctor, aim for 30 different plant foods a week. This is the variety needed, they say, to ensure that we have good gut health.
Studies have shown that people who eat at least 30 different plant-based foods a week have more diverse gut microbes than people who eat fewer than 10. "It's certainly not as black and white as a single number, but in my clinic 30 has shown to be an effective target to increase gut microbe diversity," says Dr Rossi.
The more varied our diet, the stronger our microbiome will be. "Basically different types of fibre and polyphenols feed different microbes and that is the reason why we need variety," says nutritional therapist Eve Kalinik, author of Happy Gut, Happy Mind.
According to Professor Spector, our gut microbiome is closely linked with inflammation, immune system function, mental health and metabolic health. "Because of these interactions, good gut health is a must for a long and healthy life."
However, the latest NHS stats show that the average Brit eats 3.7 servings of fruit and veg a day. Even if they were all different, that's still four short of the 30-a-week target.
At the extreme end, in 2019 it was reported that a teenage boy had been left blind and deaf by a decade-long diet of sausages, crisps and processed food.
While many of us follow expert advice and eat a rainbow of fruit and vegetables, so-called "Groundhog Day" diets have boomed in popularity. Victoria Beckham is known for her daily dish of grilled fish and steamed veg, while footballer Cristiano Ronaldo subsists on a heavy rotation of chicken, broccoli and rice.
While not quite so extreme, I calculate I hit closer to 20 than 30 on the variety scale most weeks. So I challenge myself to a week of doing better. The good news is that 30 a week is a broader church than just fruit and veg.
Dr Hazel Wallace, founder of educational platform The Food Medic, tells me that basically any plant-based food counts. "What that means is any food that comes from a plant. Yes, fruit and veg, but also beans and pulses, nuts and seeds, grains such as oats, quinoa and brown rice and wholegrain cereals." They all merit one point, but herbs and spices count only as a quarter of a point.
They also don't need to be fresh. Plant-based can come from a can, a jar or the freezer. Spices and herbs can be dried.
News that the mint in my julep and the paprika on my couscous are a quarter point each is gratefully received. Having recently worn a glucose monitor for a different article and seeing how fruit can spike my levels, I was wary about rummaging around for my 30 a week from Carmen Miranda's hat.
My experiment starts well, forcing me to break out of my quotidian with subtle changes; my grab-and-go bircher muesli from a cafe swapped for a different yoghurt pot with passionfruit and mango. Still, by midweek, I am seeing some repeat invitees. "You've already been ticked off the list!" I tell tomatoes and spinach, like a frustrated bouncer.
There are barriers to achieving such variety. We are in the middle of a cost of living crisis. Unless you are a large household, buying a wide range of ingredients a week leads inevitably to food waste.
It also flies in the face of eating seasonally: it would seem mad to start eating asparagus from Peru in January, just for the tick.
It's something Eve Kalinik is aware of with her clients. "I don't think people should be so focused on variety that they end up having to throw lots of food out."
Her tip, if you don't live in a large household with a big weekly shop, is to start using more frozen veg, as well as cans and jars.
"Things like spinach and berries are much higher in their nutritional value when they are frozen because vitamin C degrades after a vegetable or fruit has been harvested." So allotmenteers experiencing a glut should busy themselves pickling and freezing. The latter is most definitely the 30-a-week's friend.
My go-to homemade breakfast smoothie of banana, chia seeds, oats, flax seed and peanut butter is a pain to change up, but having berries, mango, spinach and kale in the freezer ready helps me broaden my repertoire.
It's a similar story for batch-cooking devotees. Here creative additionality is key. Instead of eating the identical left-over stir fry for lunch for two days, on day one I shake a pot of mixed seeds and nuts over it (Kalinik's top tip). Day two I bulk it up with a puy lentil sachet.
One evening my housemate cooks up a feast of Burmese salads; I add tofu, white cabbage, sesame seeds, broad beans, ginger and coriander among others to my burgeoning list, reflecting that being adventurous with world cuisine can elevate the standard meat-and-two-veg dinner.
On a sushi date night, I tuck into a wakame (seaweed) salad with gusto. I take multiple hits of wasabi. A simple midweek supper of scrambled eggs on toast gets a makeover by adding turmeric, cumin and chilli, another Kalinik favourite.
I'm struggling to keep count, but fortunately, the experts aren't fans of a rigorous approach anyway. "I don't think it's practical ticking off 30 plant points a week," says Dr Wallace. "But I am very aware of diversifying my diet. In the supermarket I'll say, 'Right Hazel, pick a different vegetable and look up how to cook it'. If I find myself picking up a can of chickpeas again, I'll put it down and grab cannellini. If I'm out at dinner, I'll order a side salad with my main."
After doing the maths, I'm teetering on day six at 27. So I take myself to a trendy salad bar near work that lets me pick my own ingredients; I rack up sweetcorn, black eyed peas and kale. However I walk away £10 lighter (about NZ$19), more than I would usually ever spend on a workday lunch.
Getting 30 a week has to be sustainable financially. So I head to Sainsbury's and, for the same price, fill a basket with fresh veg and pulses. I even find a mixed-leaf salad with samphire in it that carries me into the early thirties.
While I've managed to spread my load over the week, could you binge all at once and get the same health benefits? "If you're having five days of beige foods, that isn't ideal," says Kalinik.
"You're not really giving your gut microbes anything. But if you're eating veg, albeit similar, then that's probably OK. But I would say, if you're aiming to eat 30 different plant-based foods crammed into two or three days, that's going to be hard. It's best to spread it out."
On day seven I rest, certain that 30 a week can be done economically and easily. It might also break me out of my boring habits. It's not something anyone should stress about though, says Kalinik.
"The worst thing you can do for your gut health is stress. The irony is, if you're nailing 40 a week but stressed doing it, you're better off aiming for 20 and being more mindful."
How to get your 30 vegetables a week
If you are struggling to visualise what 30 plant-based foods looks in your shopping trolley, here's an example of what you might eat in a week. Compare this with your own weekly shop and see where you need to add more variety:
Tomatoes, mushrooms, broccoli, peppers, sweetcorn, spinach, potatoes, onions, peas, carrots.
Grapes, apricots, strawberries, watermelon, blueberries, raspberries, apples, bananas, oranges, kiwifruit.
Oats, brown rice, quinoa, bulgur wheat, wholegrain bread.
Legumes, nuts and seeds
Chickpeas, lentils, tinned beans, pack of mixed seeds, pack of mixed nuts.
- Source: theguthealthdoctor.com
Seven fruit and vegetables you need to try
Make a quick remoulade by grating and mixing with lemon juice, mayonnaise, Dijon mustard and chopped fresh herbs like chives and parsley.
Fennel is delicious tossed in olive oil and balsamic vinegar and roasted in the oven.
Slice up, remove the black pips and squeeze over lime juice to bring out the flavour.
Scoop out the tangy pips and have over yogurt or porridge.
5. Bulgur wheat
An excellent whole-grain alternative to couscous.
6. Black beans
These can be added to soups or stews or used as a quick side dish cooked up with garlic, chilli and cumin.
Tempeh is a plant protein made from fermented soy beans with a firmer texture than tofu. Works well as a replacement for meat in curries.
- Extra research by Sam Rice