Leek and potato. Bacon and eggs. Strawberries and cream. Some foods belong together.
And some pairings take this universal truth a step further. Pouring a shot of coffee into the batter can punch up the flavours in your chocolate cake, and a sprinkle of sea salt can offset the oozy sweetness of a caramel.
‘Synergy’ is what’s going on here – combining two individually great things to create something even greater than the sum of its parts.
What if the same could be true of healthy eating? After all, food is chemistry.
Traditionally, nutrition research has focused on testing the effects of a single active compound at a time – what happens to our bodies when we snarf down sucrose, consume calcium or pig out on protein. It’s an approach that makes for straightforward experiments with clear results.
But it doesn’t accurately represent real-world diets. Even the simplest meal, like bread and butter, is made up of a complex mixture of thousands of compounds – and, crucially, those compounds can interact.
In fact, if you routinely focus on a single supplement – an iron tablet, or a vitamin D pill – nutritionists think you could be missing out on some simple, evidence-based food hacks that’ll not only make your meals tastier but also supercharge your dietary gains.
Yes, we’re telling you that the perfect pairings for effortless healthful eating have been under our noses the whole time. And it’s not too late to introduce them to your packed lunch or dinner table.
Try matching up these following five nutritional power couples to benefit your body, brain and gut… they could even help you lose weight.
1. Fibre and polyphenols
For most of us, eating more fibre is one of the quickest and simplest ways to improve our diet. It helps to support a healthy gut microbiome, which is a key player in digestive, immune and brain health. But around 95 per cent of people in the US and the UK aren’t getting enough fibre.
“The gut microbiome is a cornerstone of health… and fibre is your gut microbes’ favourite food,” says Dr Emily Leeming, a research fellow at King’s College London and author of Genius Gut.
Fibre-rich foods include whole grains, beans and lentils, nuts and seeds, and fruit and vegetables. Chia seeds are one of the best sources – two tablespoons contain about 5g of fibre. The recommended daily intake is 25g (0.9oz).
We can’t digest dietary fibre on our own, since our bodies don’t produce the enzymes to break it down. But gut microbes do produce fibre-digesting enzymes, and when they feed on fibre in our diet, they produce beneficial molecules.
For example, fibre stimulates gut microbes to produce short-chain fatty acids, which have anti-inflammatory properties and help to support the health of the gut lining, as well as the functioning of the brain and immune system.
You can enhance the benefits of dietary fibre in the gut by combining it with other nutrients that have synergistic effects. For example, polyphenols, which are found in many fruits and berries, are prebiotics – meaning they help to feed beneficial microbes in the gut.
They also have antioxidant effects, which can help prevent cellular damage that can lead to cancer.
“While not a drug replacement, pairing fibre and polyphenols offers microbiome-mediated benefits that support long-term metabolic health,” says Lianmin Chen, professor of cardiology at Nanjing Medical University, in China.
To further amplify this microbiome-boosting effect, combine fibre and polyphenols with fermented foods, such as kimchi or live yoghurt. These foods contain live microbes and can help to increase the diversity of the gut microbiome.
“To be effective, fermented foods should be raw and unpasteurised, and polyphenol sources should be fresh or minimally processed,” Chen explains.
For example, you could eat overnight oats with kefir, blueberries and chia seeds, or try pairing sauerkraut with cheese and sliced apples. Another great option is having yoghurt with berries and ground flaxseed – for the best results, make sure that you choose a yoghurt that contains ‘live’ or ‘active’ cultures.
As if all that wasn’t enough, reaching your daily fibre targets – with the help of polyphenols – can be a major ally for healthy weight management. That’s because dietary fibre slows the absorption of sugar into the bloodstream to give you longer-lasting energy.
What’s more, high-fibre diets have been found to stimulate the production of appetite-reducing hormones in the gut, making us feel fuller and more satisfied after eating.
“Unlike our genes, which we can’t change, we can shape our gut microbiome by making small tweaks to what we eat,” says Leeming.
2. Calcium and vitamin D
It’s well known that calcium is essential for healthy teeth and bones. Getting enough calcium in your diet is important to prevent health conditions like osteoporosis, but the body’s ability to absorb calcium is limited without adequate vitamin D.
That’s why having both nutrients is crucial for bone health.
“Calcium is one of the building blocks of bones, and vitamin D helps our body to absorb it effectively,” says Nichola Ludlam-Raine, registered dietitian and author of How Not to Eat Ultra-Processed.
Vitamin D increases calcium uptake by regulating the production of calcium-binding proteins that aid its absorption by the intestines. Vitamin D also causes the kidneys to reabsorb calcium into the bloodstream, making more of it available to strengthen teeth and bones.
Certain foods, such as eggs and oily fish, are rich in vitamin D, providing a dietary source of this vital nutrient. Our bodies are also able to make their own vitamin D, and we actually get most of it this way.
But there’s a catch: vitamin D synthesis depends on sunlight, so people who live further from the equator, have darker skin, or aren’t able to spend much time outdoors may find it hard to produce enough vitamin D year-round.
“Although we do get some vitamin D from food, the majority comes from sunlight in the summer months,” Ludlam-Raine says. “The problem is that in the UK, we don’t get enough sunlight in the summer for enough vitamin D to be synthesized to last us through winter.”
For that reason, in high-latitude regions like the UK and northern US, experts recommend taking vitamin D supplements in the winter to ensure that the body can make use of the calcium in your diet.
Sunlight isn’t the only thing our bodies need to produce vitamin D. Another crucial component is magnesium, which is needed for the enzymes that synthesise and activate vitamin D to function.
In other words? Getting enough magnesium (300mg a day for men and 270mg a day for women) is a must to help your body produce vitamin D and absorb calcium. Leafy greens, such as spinach and kale, as well as nuts and seeds, are great sources of dietary magnesium.
A simple way to make sure you’re getting vitamin D and calcium in your diet is to eat cereal with milk (either dairy or plant-based) that has been fortified with vitamin D.
For a more substantial lunch or evening meal that’s rich in these synergistic nutrients, try salmon with broccoli. And, for that added boost of magnesium, you could have a salmon and spinach salad with a sprinkling of chia seeds.
You can maximise calcium absorption by adding a source of inulin – a type of fibre found in chicory root, asparagus and Jerusalem artichokes – to calcium-rich meals.
The short-chain fatty acids that are produced by gut microbes when they ferment inulin aid calcium absorption by lowering the pH of the gut.
A summery asparagus and feta salad with pine nuts is rich in inulin, calcium, and magnesium – and eating it outdoors on a sunny day will also help your body to synthesise vitamin D.
Read more:
- Most of us are eating fibre at the wrong time of day, says Harvard doctor
- Why the worst foods for weight gain aren't what you think
- This is the easiest weight-loss hack nutrition scientists wish everyone knew
3. Iron and vitamin C
Our bodies need iron to produce haemoglobin, the oxygen-carrying component of blood. If we don’t get enough iron in our diet, we can become anaemic, which can cause serious symptoms including fatigue, shortness of breath and heart problems.
Dietary iron comes in two forms: haem-iron, which is found in meat and fish, and non-haem iron, which we get from plants, such as spinach, beans, and lentils.
Our bodies have a harder time absorbing non-haem iron, though, so pairing it with complementary nutrients to boost absorption helps us make full use of the plant-based iron in our diet.
At a cellular level, haem-iron is bound together in a ring that’s very difficult to break. This structure is thought to protect the iron from other compounds in the diet, such as tannins and phytates, which can bind to it and prevent absorption.
Non-haem iron doesn’t benefit from this protective structure, so it’s more likely to pass through the intestines without being absorbed.
Pairing non-haem iron with vitamin C can help. Vitamin C increases the acidity of the intestines, which converts the ‘ferric’ iron found in plants into ‘ferrous’ iron, which is more readily absorbed into the bloodstream.
One study found that consuming vitamin C and iron in the same meal enhanced iron absorption by 67 per cent.
Research has shown that vitamin C is most effective at increasing iron uptake when the two nutrients are consumed within the same meal. But before you crack out the supplements, vitamin C pills seem to have little benefit for iron absorption – so you’re better off pairing these two nutrients together in your cooking.
Meanwhile, iron supplements generally contain non-haem iron – so if you’re using these supplements to treat anaemia, for example, then taking them with a source of vitamin C (like orange juice) will maximise their benefit.
Another way to boost your iron intake is to combine iron-rich foods with sulphur compounds, such as allicin and diallyl disulfide. Alliums – especially onions and garlic – are rich in these beneficial compounds.
Although the mechanism isn’t fully understood, scientists have suggested that sulphur compounds increase iron absorption by forming soluble compounds with iron, or by increasing the expression of iron channels in the intestinal wall.
Crushing or chopping these ingredients before cooking maximises their beneficial effects by releasing an enzyme called alliinase (the one responsible for producing allicin).
“Pairing legumes, which are rich in plant protein and non-haem iron, with alliums like onions or garlic offers notable health benefits, including enhanced iron absorption, reduced inflammation, and improved blood glucose and lipid levels,” Chen says.
Allicin and diallyl disulfide also help the intestines to absorb zinc, an essential micronutrient involved in immune function and wound healing, bone growth, and hormone production. They can also help to support the gut microbiome.
Dishes rich in iron, vitamin C and allicin include tomato and lentil curry with sauteed garlic and onions; hummus and red peppers with fresh garlic; and spinach and mandarin salad with red onions.
4. Fat and lycopene
Many important nutrients in the diet are hydrophobic, meaning that they don’t mix with water, and this makes it hard for them travel through the watery environment of our intestines. So, they need to hitch a ride on the fats in our diet.
When these ‘fat-soluble’ nutrients encounter dietary fat, they’re integrated into tiny fat bubbles known as micelles. The micelles transport them through the gut to reach the intestinal cells, where they can be absorbed.
Fat-soluble nutrients include vitamins A, D, E and K, as well as carotenoids (the bright, natural pigments found in fruits and vegetables like carrots and tomatoes), meaning that not getting enough fat in our diet can impact our levels of all of these nutrients.
Through its role in transporting fat-soluble nutrients, dietary fat is important for maintaining healthy eyes, skin, bones and hair, as well as for immune function, wound healing and healthy ageing.
An important fat-soluble compound is lycopene, a type of carotenoid with antioxidant properties, which helps protect your skin against sun damage and ageing. Lycopene is found in tomatoes, as well as other red fruits and vegetables such as red peppers, red cabbage and watermelon.
Heating these foods before eating them helps to break down the cell membranes, making the lycopene more accessible for the body to absorb.
“By cooking tomatoes, you can make the lycopene, which is a potent antioxidant that’s naturally present in tomatoes, more easily available,” Leeming explains. One study found that cooking tomatoes for just 15 minutes can double the amount of lycopene the body can absorb.
To tap into the synergistic benefits of fats and lycopene, try mediterranean vegetables roasted in olive oil, pasta with tomato sauce, or shakshuka.
5. Turmeric and black pepper
For millennia, cultures around the world have lauded turmeric for its anti-inflammatory and antioxidant properties. Despite decades of research, though, scientists are yet to pin down the mechanism behind turmeric’s reported benefits.
The most promising candidate so far is curcumin, a polyphenol found in turmeric. But curcumin’s beneficial effects on the body are often hampered by a combination of poor absorption in the intestine, and rapid metabolism and expulsion by the liver.
Black pepper can boost curcumin’s effects because it contains piperine, which inhibits the breakdown of curcumin in the liver.
One small-scale study reported that combining this compound (which gives black pepper its strong flavour) with curcumin increased the amount of curcumin absorbed into the bloodstream by a whopping 2,000 per cent.
Try adding a dash of black pepper to a golden turmeric latte, an Indian curry, or a Moroccan tagine to unlock the combined benefits of curcumin and piperine. “You could keep them next to each other in your pantry, so that you [remember to] use both at the same time,” says Ludlam-Raine.
It’s worth noting that while many studies have reported anti-inflammatory and anti-oxidant effects of curcumin, scientists have so far been unable to harness its effects to develop pharmaceutical drugs.
“Food can have medicinal properties, but it’s not medicine,” Ludlam-Raine cautions. Still, she explains, while “turmeric is not a replacement for anti-inflammatory medications,” including it as part of a balanced diet can enhance the taste experience and may have positive effects on joint, brain and metabolic health.
Another word of caution: at very high concentrations, curcumin can be toxic.
So, since piperine affects how the liver processes curcumin, if you’re taking turmeric supplements (which contain much higher doses than you’d get through food), it’s not such a good idea to sprinkle black pepper on them.
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