Forget five fruit and veg a day... Think 30 varieties a week

We are used to being told to eat our vegetables, and have five to seven portions of fruit or vegetables a day, as it is linked to lower mortality and better long-term health.

Now, we are being told that it is not just quantity but variety that counts.

The most recent evidence suggests that eating 30 different plants a week can boost the healthy bacteria in your gut, which can have major implications for your overall health.

While 30 sounds like a lot, it is not just fruit and vegetables. Wholegrains, spices, seeds, and herbs all count.

We have been brought up to think that an apple a day will keep the doctor away, that carrots are good for your eyesight, and pears are good for your bowel habit. Now it seems that those picky microbes in your gut prefer that you eat apples, carrots and pears one day and eat at least 27 different plants on the other days of the week. This includes plants we might not normally consider, including herbs, seeds, nuts and spices as well as well as beans, pulses and peas and wholegrains like brown rice, oats and whole-wheat flour.

The recommendation to eat 30 different plants a week is based on research from the American Gut Project (2018) involving a collaboration of researchers from the US, the UK and Australia. ZOE Co-Founder and author of Food for Life, Tim Spector led the UK arm of the research - the British Gut Project. The research involved over 10,000 participants sharing details of their eating habits as well as stool samples to analyse the potential links between diet and gut microbes.

The study clearly showed that participants with the greatest diversity of plants in their diets had the widest diversity of healthy gut microbes. Participants who ate 30 or more different plants per week were more likely to have healthy gut microbes than those who ate 10 or fewer. Their stool samples also contained higher levels of healthy chemicals produced by the microbes.

In Food For Life, Prof Spector explains that while most of the highly processed and refined food we eat is absorbed in the small intestine, it is in the large bowel where the real work on ‘real’ food happens. At 1-2 metres long, the large bowel is much shorter than the small intestine. But this is where all the crucial work happens in of food and health.

In the large intestine, the microbes liberate substances called polyphenols to be either used directly or converted into more complex chemicals that help to fight chronic diseases such as diabetes, heart disease, depression, cancer and obesity.

In one study of 2,000 twins, those eating large amounts of food containing polyphenols had a 20% lower risk of developing obesity, even after adjusting for intake of fibre. Fibre and polyphenols were both independently found to be a predictors of weight gain or weight loss over ten years in the same group.

Some polyphenol chemicals and their breakdown products have been shown to have a whole range of functions, including improving the resilience of the intestinal wall, sending signals to our immune cells, damping down inflammation, suppressing allergies as well as suppressing appetite.

The latest evidence shows that our microbes actually help inform us about what foods we should be eating, even causing us to crave certain foods, suggests Prof Spector.

“Our microbes literally send chemical messages to our brain to encourage us to eat what they need for survival.”

That means that if you have lots of unhealthy microbes in your gut, this can lead to a vicious cycle where you crave foods that help these unhealthy bacteria to thrive, which in turn can drive you to eat more unhealthy foods.

This is what happens when we eat a lot of ultra-processed foods.

What plants should we be eating?

While eating 30 plants a week may sound daunting, when you include wholegrains, spices, herbs, nuts and seeds, it becomes much less challenging.

A range of vegetables can include carrots, cabbage, broccoli, rocket, onions, asparagus, tomatoes, spinach and sweet potatoes.

Fruits can include apples, oranges, berries, figs, kiwis, bananas, pears, tomatoes, and avocados.

Legumes include beans, peas, lentils and chickpeas - all bursting with fibre, protein, folic acid, and minerals.

Wholegrains that can count toward your 30 include wholegrain flour like wheat and rye, brown rice, oats and quinoa.

Nuts and seeds include cashews, almonds, pine, pistachios, walnuts, chia seeds, flaxseeds, pumpkin, sesame and sunflower seeds.

Herbs count whether they are fresh or dried, including basil, mint, oregano, parsley, sage and tarragon.

Spices include pepper, cumin, paprika, saffron, turmeric, ginger, nutmeg and allspice.

Because we tend to use seeds, herbs and spices in small amounts, using them several times a week can help to maximise their benefits.

Colours matter as well – different coloured plants provide more of a diversity of polyphenols for healthy gut bacteria to feed on, which increases the diversity of the microbiome.

Even different colours of the same fruit, like red and yellow and green peppers, can provide a variety of polyphenols and increase the diversity of the microbiome.

Tips to increase the diversity of plants eaten every week include stocking up with a wide range of plants, including tinned fruit and beans, dried herbs and packets of lentils or chickpeas.

Nuts or seeds can be added to salads and tossed into natural yoghurt with fresh berries.

Once you focus on a variety of plants in every meal, it is easy to get them to add up. I have porridge in the morning, cooked with milk and blueberries, topped with yogurt, pumpkin and sesame seeds. I bring a lunchbox to work with a handful of mixed nuts, an orange or banana and some grapes.

For dinner, I often make a salad with tomatoes, cucumber and pomegranate seeds or pine nuts or a mix of stir-fried vegetables – onions, garlic, carrot, peppers, courgettes.

I rarely eat anything from a sliced pan – the fresh wholegrain bread is much better as is brown, red or black rice or brown pasta.

Once you get used to wholegrains, the food tastes much better too.

It doesn’t work all of the time – I am just as inclined to have a pizza or a Chinese as everyone else, but it works a lot of the time. It helps with energy and sleep as well as, hopefully, keeping me well and independent into a ripe old age.