Add-ins are one of those things that can genuinely improve a smoothie or quietly make it worse, depending on what you're adding to what. We've been asked enough times about which ones work together that it seemed worth writing it down.

Chia seeds: texture and staying power

Chia seeds don't add much flavour, but they add a slight texture and a meaningful amount of fibre and fat. They work in almost any smoothie. The one thing to know is that they absorb liquid quickly, so if you're not drinking your smoothie immediately, it'll thicken noticeably within ten minutes. That's not a problem if you're sitting at the bar. It's worth knowing if you're taking it on the tube.

Milled flaxseed: the invisible add-in

Milled flaxseed has almost no flavour and blends in completely. You won't taste it. It adds omega-3 fatty acids and a little fibre. We use milled rather than whole because whole flaxseeds pass through largely undigested, which defeats the purpose. If you want to add something without changing the taste of your smoothie at all, flaxseed is the one to choose.

Almond butter: richness and protein

A teaspoon of almond butter makes a smoothie noticeably richer and more filling. It works best with fruit-forward blends where you want to add substance without changing the flavour profile too much. It's particularly good in the Stone & Gold and the Dark Berry. We'd be more cautious adding it to a green smoothie, where the nuttiness can clash with the greens.

Fresh ginger: heat and brightness

A small piece of fresh ginger adds warmth and a sharpness that lifts the whole drink. It works well in green smoothies, in anything with carrot or beetroot, and in the Stone & Gold. The key word is small: a thumb-sized piece is plenty. More than that the ginger takes over. We grate ours fresh each morning rather than using a paste, because the flavour is noticeably brighter.

What not to combine

The combinations we'd steer you away from: almond butter in a very thin, water-based smoothie (it doesn't blend smoothly and you get lumps), ginger in anything with coconut milk and berries (the flavours fight), and chia seeds in a juice (they just sink to the bottom). When in doubt, ask at the bar. We'll tell you what we'd actually do.

All add-ins are listed on the board at the bar. Prices start at £0.80 per add-in. You can add up to two per smoothie.