Raspberries

Why it matters

Most fruits provide 2 to 3g of fibre per 100g. Raspberries provide around 6 to 7g, which puts them among the highest-fibre fruits you can eat. They are also relatively low in sugar, so they bring sweetness without much effect on blood sugar.

Adults in the UK eat only about 16 to 17g of fibre a day on average, against a recommended 30g. A bowl of raspberries closes a meaningful part of that gap.

What's inside

Besides fibre, raspberries provide vitamin C, manganese and vitamin K. Their colour comes from anthocyanins, and they are one of the richest dietary sources of ellagitannins, polyphenols that gut bacteria convert into compounds called urolithins, although people vary widely in how much urolithin their gut bacteria make.

Much of the research on these polyphenols is still in the lab or in small human studies, so it is too early to make firm claims about them.

For men

The useful effect is on blood sugar and weight. High-fibre, low-sugar foods help keep blood sugar steady, and insulin resistance is closely linked with lower testosterone. Swapping sugary snacks for berries is a small change that adds up. See does sugar lower testosterone?

Vitamin C and polyphenols are antioxidants, and antioxidant-rich diets are linked with better sperm quality in observational research, though that is association rather than proof.

For women

Fibre is linked with more oestrogen being excreted rather than reabsorbed, partly through the gut bacteria collectively called the estrobolome, though this research is still early. See your gut and your hormones.

After menopause, steadier blood sugar and a healthy weight both matter more, and raspberries are one of the few fruits that are high in fibre and low in sugar at the same time.

How to eat it

Frozen raspberries are as nutritious as fresh and far cheaper outside summer. Stir them into porridge, Greek yogurt or overnight oats straight from the freezer, or warm them gently into a quick sauce.

Try the high-protein porridge with raspberries and almonds. An 80g portion, about 20 raspberries, counts as one of your 5 a day.

Worth knowing

Raspberry ketones are not raspberries. The weight-loss supplements sold under that name contain a synthetic compound, at doses no raspberry could provide, and there is no good human evidence that they help with weight loss.

Raspberry leaf tea, often taken in late pregnancy, is made from the leaves rather than the fruit. Evidence for it is weak; speak to your midwife before using it.

Fresh raspberries spoil quickly. Keep them in the fridge unwashed and rinse just before eating.

Bottom line

Raspberries are one of the highest-fibre, lowest-sugar fruits you can eat, and frozen ones are just as good; skip the raspberry ketone pills.

Related reading: Does sugar lower testosterone?, the symptoms of estrogen dominance and the best diet for menopause. Browse the full food library.