Foods for Hydrated Skin: What to Eat

Ground flaxseed or flax oil

Water loss through the skin (TEWL) is the water your skin lets escape into the air; the lower it is, the better your skin barrier is holding on to moisture.

Four small trials have tested oils rich in ALA, the plant omega-3. The biggest gave 120 Japanese women aged 45 to 65 oil blends with 0.97 to 2.13 g of ALA a day, or a placebo, for 12 weeks (Ando et al., 2025). Water loss through the skin, the main outcome, didn't change. Hydration rose in a secondary analysis, though the top dose only trended above placebo. Three of the four authors work for an edible-oil company.

A 2026 trial gave 60 adults aged 20 to 59 with mildly dry, itchy or red skin 2.5 g a day of a manufactured linseed (flax) oil, carrying 0.9 g of ALA, or a sunflower oil placebo, for 8 weeks. Cheek hydration rose compared with placebo, while water loss didn't differ (Fukagawa et al., 2026). Four in five of the volunteers were men.

Two older trials gave flax oil capsules. In one, water loss fell by about 10% within 6 weeks on 2.2 g of oil fats a day, though hydration rose on placebo too (De Spirt et al., 2009). In the other, 13 women per group took flax oil for 12 weeks, and their water loss, roughness and scaling fell while hydration rose (Neukam et al., 2011).

Why fats could matter: your skin barrier is about 50% ceramides, 25% cholesterol and 15% fatty acids. Skin makes some of these fats itself and gets the rest from outside the skin (Feingold and Elias, 2014).

How to eat it: we found no trial of ground flaxseed itself. Flaxseed is the richest plant source of ALA, which makes up about 22% of the whole seed. A tablespoon of ground flaxseed weighs 7 g, and 1 to 2 tablespoons a day is the usual suggestion (Kunutsor et al., 2025). By our arithmetic, 1 tablespoon carries about 1.5 g of ALA, inside the range the trials used. Buy it ground or grind it yourself, since whole seeds need grinding for your body to absorb what's inside. Not into flax? Chia seeds and walnuts are rich in omega-3s too, but we found no skin trial of either.

Kiwi, strawberries and peppers

The newest study, from 2026, looked at 74 healthy Korean adults. Vitamin C and fibre intake went with better skin hydration or skin pH, but only in people with one type of gut bacteria (Kim et al., 2026).

The biggest study is older. In 4,025 US women aged 40 to 74, those who ate more vitamin C had slightly lower odds of age-related dry skin (odds ratio 0.93) (Cosgrove et al., 2007). That's a link, not proof, and the first author worked at Unilever.

Why it might help: in lab studies, vitamin C helps skin cells make barrier fats, which may help skin protect itself from water loss (Pullar et al., 2017).

How much: women need 75 mg a day. Kiwi, strawberries and red peppers are among the richest sources, and raw fruit and vegetables are best (MedlinePlus). In one study, adding half a gold kiwi a day took people's vitamin C intake from about 30 mg to about 75 mg (Carr et al., 2013).

Oily fish

We found no trial that measured skin hydration after people ate fish. The closest evidence is krill oil, a capsule carrying EPA and DHA, which are long-chain omega-3s. A 2024 paper reported two small trials; in one, 50 adults took 2 g of krill oil a day or a placebo (Handeland et al., 2024). Results were checked at 6 and 12 weeks. In both trials, krill oil slightly cut water loss through the skin (in the 2 g group, from 14.25 to 13.02 g/m²/h) and raised hydration compared with placebo. The krill oil maker funded the trials, and two of the three authors work for it.

Oily fish such as salmon and sardines are particularly high in long-chain omega-3s. The NHS suggests at least 2 portions of fish a week, including 1 of oily fish, with a portion around 140 g. Women who haven't been through the menopause should have no more than 2 portions of oily fish a week (NHS). That's why we suggest 1 to 2 portions.

Green tea or matcha

The one trial we found used a drink made from green tea polyphenols, not brewed tea. In 60 women over 12 weeks, it improved skin's "water homeostasis", its water balance, along with elasticity, roughness, scaling and density, compared with a placebo drink (Heinrich et al., 2011). That drink held 1,402 mg of catechins a day. Three cups of brewed green tea supply about 405 mg (Khokhar and Magnusdottir, 2002), so by our arithmetic the drink matched about ten cups.

Our suggestion of 2 to 3 cups a day gives under a third of that dose, so treat it as a nice extra. We found no skin trial of matcha. In a 2023 lab test of 15 green teas, bagged and gunpowder teas scored higher than matcha on phenolics, a family of antioxidants, and on antioxidant capacity (Meyer et al., 2023).

Collagen powder

Collagen is a supplement, not a food, but it's everywhere in hydration talk. A 2025 analysis pooled 23 trials with 1,474 people (Myung and Park, 2025). Overall, collagen looked helpful. Split by funding, though, the trials not funded by companies found no effect on hydration, elasticity or wrinkles, while company-funded ones did. The high-quality trials found no effect either.

A 2026 review counted hydration gains in 10 of 15 trials, but rated most trials at high risk of bias (Bassila et al., 2026). Trials used 1 to 10 g a day (Sun et al., 2022). We found no trial of bone broth and skin hydration.

Avocado

In a 2022 trial, 39 women aged 27 to 73 ate one avocado a day or kept to their usual diet for 8 weeks. Hydration didn't change compared with the usual-diet group, though forehead skin got firmer in the avocado group (Henning et al., 2022). So enjoy it for its taste, not for hydration.

Almonds

Three trials have tested almonds, and none found a change in hydration or water loss. In the longest, women past menopause got 20% of their daily calories from almonds or a matched snack for 24 weeks (Rybak et al., 2021). In another, 39 women ate 1.5 oz of almonds or pretzels daily for 12 weeks (Li et al., 2021). A 16-week trial found no change in water loss (Foolad et al., 2019).

Water and coffee

The best water trial is small. In a 2024 study, 43 women in their 20s to 40s finished 4 weeks of 2 extra litres of water a day, moisturiser three times a day, both, or neither (Seol et al., 2024). Extra water didn't change hydration, and moisturiser did more.

In an older study with no comparison group, 49 young women added 2 litres a day for 30 days, and hydration rose, most in those drinking under 3,200 mL a day (Palma et al., 2015). A 2018 review called the evidence weak and said the reason water might help is unknown (Akdeniz et al., 2018).

A 2024 snapshot of about 300 people found no hydration difference between those drinking under 1 litre and over 3 litres a day (Ding et al., 2024). The same study found that people who'd had coffee in the previous 2 hours had higher hydration readings. It was one reading with a new kind of probe, so it only suggests coffee doesn't dry skin. Pooled trials of coffee polyphenol supplements didn't raise hydration (Sun et al., 2022).

Food counts toward your water: about 22% of Americans' water comes from food, and watermelon, strawberries, celery and spinach are 90 to 99% water (Popkin et al., 2010). We found no trial of water-rich foods and skin hydration. For comparison, creams raised hydration in all six labs of a 349-person study (Heinrich et al., 2003).