1. Vitamin D

Vitamin D is a fat-soluble vitamin that's critical for many aspects of health, including the health of your skin.

Keratinocytes are skin cells that make up the majority of the outer layer of your skin, known as the epidermis.

Keratinocytes are the only cells in your body that can form vitamin D from its precursor 7-Dehydrocholesterol (7-DHC) and turn it into a form that your body can use.

Vitamin D plays an integral role in skin barrier function and skin cell growth, as well as maintaining the skin immune system, which acts as a first line of defense against harmful pathogens.

Some research has shown that low blood levels of vitamin D are associated with skin conditions, including eczema and psoriasis — both of which can cause dry skin.

Additionally, vitamin D supplements have been shown to significantly improve symptoms of skin disorders that cause dry, itchy skin, including eczema.

What's more, research has indicated a correlation between vitamin D and skin moisture.

A study in 83 women found that those who had low vitamin D levels had lower average skin moisture than participants who had normal vitamin D levels, and that as blood levels of vitamin D increased, skin moisture content increased as well.

Another small 12-week study in 50 women observed that daily treatment with a nutritional supplement containing 600 IU of vitamin D led to significant improvements in skin hydration.

However, the supplement contained a combination of nutrients, so it's unclear whether treatment with vitamin D alone would have resulted in the same positive outcome.

A large percentage of the population is deficient in vitamin D, and given that the nutrient is essential for skin hydration, supplementing with it may help combat dry skin.

Vitamin D supplements are widely available in stores and online.

Be sure to discuss their use with your healthcare provider first and look for products that have been third-party tested to ensure the highest quality.

Summary

Research shows that low levels of vitamin D may increase the chances of dry skin. Therefore, supplementing with this nutrient may help increase skin hydration.

2. Collagen 

Collagen is the most abundant protein in your body and accounts for 75% of your skin's dry weight.

Some research has shown that taking collagen-based supplements may have a range of benefits for your skin, including decreasing wrinkle depth and increasing skin hydration.

A study in 69 women found that participants who consumed 2.5–5 grams of collagen per day for 8 weeks had significant improvements in skin elasticity and also experienced increased skin hydration, compared with a placebo group.

Another 12-week study in 72 women noted that taking a supplement that contained 2.5 grams of collagen peptides along with a blend of other ingredients like vitamin C and zinc significantly improved skin hydration and roughness, compared with a placebo group.

However, the supplement contained other nutrients, so it's unknown whether collagen alone would have had the same effects.

Plus, the study was funded by the supplement manufacturer which may have affected the study results.

A 2019 review of 11 studies concluded that taking 2.5–10 grams of oral collagen supplements per day for 4–24 weeks increased skin hydration and treated xerosis, a medical term for dry skin.

If you want to try a collagen supplement to help with your dry skin, speak with your healthcare provider before purchasing a third-party certified product locally or online.

Summary

A good amount of evidence supports the use of collagen supplements for increasing skin hydration and treating dry skin.

3. Vitamin C 

Vitamin C acts as a powerful, skin-protective antioxidant and is essential for collagen production, making it an important nutrient for skin health.

In fact, the skin contains very high levels of vitamin C, with some research finding a concentration of up to 64 mg of vitamin C per 100 grams of the epidermal skin layer.

Unsurprisingly, studies have shown that increasing dietary vitamin C through vitamin C supplements may improve many factors of skin health, including skin hydration.

Some test-tube studies have found that vitamin C may enhance skin barrier function and help reduce water loss, which may help prevent dry skin.

Plus, some studies have shown that when used in combination with other nutrients, vitamin C may help enhance skin moisture.

For example, a 6-month study in 47 men demonstrated that taking a supplement that contained 54 mg of vitamin C, as well as marine protein and a combination of other nutrients, significantly improved skin hydration, compared with a placebo group.

Other studies in women have shown similar results.

A study in 152 women found that participants who took a supplement that contained 54 mg of vitamin C, as well as zinc and marine protein, had significantly reduced skin roughness, compared with a placebo group.

However, in most of the available research on vitamin C's effect on dry skin, vitamin C is combined with other nutrients, making it impossible to tell whether the nutrient would have the same effect if it was used on its own.

Plus, many of the studies were sponsored by the pharmaceutical companies that manufactured the product being evaluated, which may have affected study results.

Regardless, based on the most current research, supplementing with vitamin C may improve overall skin health and help combat dry skin.

As with any new supplement, you should speak with a healthcare professional before adding a vitamin C supplement to your diet. These products are widely available in stores and online.

Summary

Vitamin C is an integral nutrient for skin health. Consuming supplemental vitamin C may improve dry skin, according to some studies. However, more research on its effects on dry skin is needed.

4. Fish Oil

Fish oil is well known for its skin-health-promoting properties.

It contains docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), two essential fatty acids that have powerful anti-inflammatory and healing properties and have been shown to benefit the skin in many ways.

Dietary supplements with fish oil may help boost skin hydration and improve the fatty acid barrier of the skin, which helps maintain hydration.

A 90-day study in rats with acetone-induced dry skin found that high-dose oral fish oil supplements significantly increased skin hydration, reduced water loss, and resolved dryness-related skin itching, compared with rats that didn't receive the fish oil.

In fact, the study noted that the fish oil group had a 30% increase in skin hydration after 60 days of treatment.

Additionally, research indicates that daily treatment with doses of fish oil ranging from 1–14 grams of EPA and 0–9 grams DHA for 6 weeks to 6 months improved symptoms of psoriasis — a chronic, inflammatory skin disease — including scaling or dry, cracked skin.

Fish oil has also been shown to decrease skin inflammation and protect against sun damage, making it an all around skin-friendly supplement.

There are many great, third-party-certified fish oil products available in stores and online. Speak with your healthcare provider first to determine the best choice and dosage for your needs.

Summary

Fish oil may help improve skin hydration and decrease moisture loss. Plus, it has been shown to improve dry, scaling skin in those with psoriasis.

5–8. Other Supplements for Treating Dry Skin

In addition to the nutrients listed above, studies have shown that supplementing with several other compounds may be an effective way to improve skin moisture.

1. Probiotics. A study found that supplementing both mice and humans with Lactobacillus plantarum bacteria improved skin barrier function and skin hydration after 8 weeks. However, more research is needed.
2. Hyaluronic acid. Hyaluronic acid is often used topically to improve skin hydration, but recent research shows that ingesting this compound in combination with other nutrients may significantly increase skin hydration.
3. Aloe vera. A study in 64 women found that supplementing with fatty acids derived from aloe vera for 12 weeks significantly improved skin moisture and skin elasticity, compared with a placebo.
4. Ceramides. Ceramides are fat molecules that are important components of healthy skin. Some research has shown that supplementing with ceramides may increase skin hydration, which may help treat dry skin.

Some research suggests that the supplements listed above may help enhance skin moisture and treat dry skin.

However, more research is needed before these compounds can be recommended as effective ways to naturally relieve dry skin.

Summary

Supplementing with probiotics, hyaluronic acid, aloe vera extracts, and ceramides may improve dry skin, but more research is needed.

Additional Considerations

Although taking certain supplements may help improve dry skin, several other factors can contribute to skin dryness and should be considered.

For example, dehydration is a common cause of dry skin, so upping your water intake can be a healthy and easy way to improve skin hydration.

Following an unhealthy diet, having micronutrient deficiencies, and not eating enough may also cause or worsen dry skin.

Additionally, certain diseases, including kidney disease, anorexia, psoriasis, and hypothyroidism, as well as environmental allergies can cause dry skin.

Therefore, it's important to talk to your healthcare provider if you're experiencing significantly dry, irritated skin to rule out more serious health conditions.

Summary

Dry skin can be a sign of an underlying health condition, so it's important to contact your healthcare provider if you have unexplained, significantly dry skin.

The Bottom Line

Dry skin is a common condition that can be caused by a number of factors, such as dehydration, allergic reactions, and diseases like hypothyroidism.

Research has shown that taking certain vitamins and other nutritional supplements, including vitamin D, fish oil, collagen, and vitamin C, may help improve skin hydration and help keep your skin healthy and nourished.

However, although the supplements on this list may act as helpful tools for people who have dry skin, it's important to talk to your healthcare provider if you're experiencing unexplained, chronic dry skin, as this can be a sign of an underlying medical condition.