I’ve spent my career examining how profoundly our diet affects our skin health - and how we age as a result. When our skin isn’t getting what it needs, the top layer, or epidermis, begins to get dry or flaky, while our middle layer, the dermis, which plays the biggest role in retaining youthful skin, loses its bounce. Here’s what I eat to keep my skin looking younger for longer.

Chai

It’s fragrant and delicious, and when I get up at 5am it wakes me up in a gentle way. If I have time, I’ll make it from scratch using a blend including Ceylon tea leaves. Grown on the hillsides surrounding Nuwara Eliya, Sri Lanka, close to where I was born, they are particularly high in catechins and theaflavins, plant chemicals that have remarkable anti-inflammatory and antioxidant properties, which can help prevent sagging and wrinkles.

Cinnamon is in there too. Research has shown that just half a teaspoon of cinnamon per day can help to curb high blood sugar levels in those with type 2 diabetes, pre-diabetes or polycystic ovarian syndrome, along with nutmeg, cloves and ginger. Sugar can accelerate skin ageing by a process called glycation and contribute to breakouts of acne for some.

Rainbow-coloured veg

To keep skin looking young, what we want is a really vibrant, colourful diet with plenty of fruits and vegetables: it’s that cliche of eating the rainbow. But it works, as each of those different colours is down to a different antioxidant, such as betalain in beetroots, lutein in spinach, anthocyanins in blueberries and bioflavonoids in peaches, which help to target free radical damage from the likes of ultraviolet light pollution. Free radicals are responsible for collagen deformation in our skin, which is when it begins to sag, is no longer bouncy, and fine lines appear; colourful veg can help stave that off.

Oily fish

I aim to eat at least one or two fillets of oily fish per week. Omega-3 fatty acids, found in fish such as salmon, sardines, trout or mackerel, are critical to maintain skin-moisture levels: I cannot stress enough how important eating more of it is for supple, healthy skin, reducing inflammation and promoting wound healing. It really is one of the most important nutritional changes you can make. I call keeping your omega-3 levels topped up “moisturising from within”. In conditions such as rosacea the skin barrier is often compromised and anti-inflammatory good fats will help reverse the damage. Protein-rich foods such as fish can also help to support skin healing after acne breakouts and the production of collagen, as will vitamin C.

I also recommend moderating refined sugar intake – not excluding it as that would be boring – and reducing cow’s milk for a period of time to see if breakouts diminish.

If you don’t eat fish, omega-3 supplements can be a useful alternative – or, you can get it from plant-based sources such as ground flaxseeds or chia seeds.

Lemon and cucumber water

I’m not one who can drink two gallons of water a day. But I take a bottle with me everywhere and add lemon and cucumber to make it more interesting. When we are dehydrated, skin loses elasticity; drinking enough helps to support blood flow to the skin, which delivers nutrients and removes waste products. Drinking water might not turn back the clock, but you’ll still feel better for it.

Yoghurt

A daily serving of probiotics, such as live yoghurt, introduces additional good bacteria to the gut. There is increasing evidence to support a link between the gut microbiome and skin health, primarily by dampening unwanted inflammation, a trigger for premature ageing and lacklustre skin.

From our brain to our skin, the trillions of bugs living in the lining of our gut are orchestrating our immune system, our hormones and how we think and feel, so keeping these in check is crucial.

Some studies have linked drinking milk to acne, with low-fat varieties being worse for triggering breakouts than the regular kind, but we don’t have good enough evidence that other dairy foods such as yoghurt and cheese pose a problem. If you find your skin is prone to flare-ups after consuming it, try eliminating it from your diet and see if that helps.

Dark chocolate with hazelnuts

Hazelnuts, almonds, pistachios and cashews are rich in prebiotics, which are the plant fibres the probiotics in our gut need to feed on. They are key for a balanced gut microbiome, and therefore skin. I like to think that some after-dinner chocolate with nuts in it is helping the ageing process, too.

Chocolate can also be rich in antioxidants such as catechins, anthocyanidins and proanthocyanidins, but not all are made equal. Check the ingredients list to look for as few ingredients as possible. The good stuff contains cocoa mass, sugar, cocoa butter and sometimes vanilla and that’s it, and ensure it’s at least 70 per cent cocoa, as higher percentages have greater concentrations of antioxidants.

While people think of sugar (higher in milk or white chocolate) as contributing to weight gain, it can also cause the skin to sag, forming molecules in the dermis. When these attach to our collagen fibres, they become stiff and cause the skin to lose plumpness.

Sri Lankan dhal

I love spice, and a curry such as dhal, or Sri Lankan parippu, is an easy go-to for a complete meal in the evenings – particularly when you need something quick and easy to feed the family. Not only does it feel like a hug in a bowl, but it combines red lentils, enriched with fibre, protein and minerals, antioxidants, including turmeric and cinnamon, and probiotics, thanks to the kefir raita, which I serve on the side. If you add a wholegrain such as brown rice, you’ll get a good helping of inositol, which helps to regulate blood sugar in those with polycystic ovary syndrome, too. The better your diet is, as a rule, the better your skin will look.

Sauerkraut and kefir

Focus on supporting the gut microbiome with pre and probiotic foods, such as sauerkraut and kefir, to optimise microbe diversity; there is increasing evidence to support the interaction between the gut microbiome and the skin microbiome and the interplay between the two.

As told to Charlotte Lytton

The Telegraph, London