Why is Hydration so Important for Skin Health?

Hydrated skin means having enough water to maintain its structure and elasticity. While hydration won’t eliminate pores or wrinkles, it is certainly essential for a plump, glowing complexion. This is achieved through a combination of internal and external factors, including drinking water. I highlight this because although it isn’t the only factor in skin hydration, drinking water does definitely play a role - despite some beauty influencers claiming otherwise.

Let’s explore the science of hydration, the differences between dehydrated and dry skin and the factors that influence skin hydration. We will also touch on how we can achieve hydrated skin.

Dehydrated Vs Dry Skin

Although the terms dry skin and dehydrated skin are often used interchangeably, they refer to two distinct concerns that require different approaches to manage effectively. In simple terms, dehydrated skin lacks water, while dry skin lacks oil. And yes, it is possible to experience both at the same time.

Dehydrated skin occurs when the skin lacks water, and it can affect any skin type, even oily or combination skin. This condition is usually triggered by factors like lifestyle choices, environmental stressors, and certain skincare products. Dehydrated skin often appears dull, with more prominent fine lines and wrinkles, sunken under-eyes, and a tight, dry feeling, though paradoxically, it can still produce excess oil, leading to greasiness.

Dry skin, on the other hand, is a skin type determined primarily by genetics. People with dry skin naturally produce less oil (sebum), which is essential for locking in moisture and maintaining a healthy skin barrier. While genetics play a major role, factors like ageing, over-exfoliation, and cold, dry weather can further strip the skin of its natural oils, leading to flakiness, rough texture, and increased sensitivity.

Since the root causes differ, so should the treatment approach. Dehydrated Skin benefits from replenishing water content both internally and externally. Drinking enough water, eating water-rich foods, and using skincare ingredients like hyaluronic acid, glycerin, aloe vera, and niacinamide can help restore hydration and support the skin’s barrier.

Dry Skin, in contrast, requires restoring and sealing in lost oils. This means consuming healthy fats (like extra virgin olive oil, avocados, and oily fish) and applying nourishing, lipid-rich products. Ingredients like jojoba oil, rosehip oil, squalane, shea butter, and ceramides are effective at replenishing oils and preventing moisture loss.

What Impacts Skin Hydration?

To understand what affects skin hydration, it can be helpful to first look at how our skin is structured. The skin has three main layers, each contributing to hydration in unique ways:

• Epidermis (Outer Layer): This is the skin’s protective shield and home to the skin barrier (or stratum corneum). Often described as a “brick-and-mortar” structure, skin cells (the bricks) are held together by lipids (the mortar). This barrier prevents excessive water loss while keeping out certain compounds, allergens and pathogens. When the barrier is compromised, water escapes more easily through transepidermal water loss (TEWL), leaving skin vulnerable, dehydrated and sensitive.

• Dermis (Middle Layer): Rich in collagen, elastin and blood vessels, this layer nourishes the epidermis and contains natural humectants like hyaluronic acid that attract and bind water, giving the skin its plump, elastic quality.

• Hypodermis (Deepest Layer): This fatty, cushioning layer helps regulate temperature and indirectly supports skin hydration by maintaining the skin’s overall structure and resilience.

When these layers are healthy and functioning properly, the skin stays smooth, elastic, and well-hydrated. But when they’re compromised, whether by internal or external influences, the skin loses its ability to retain moisture, resulting in dullness and accelerated signs of ageing.

A wide range of factors can affect hydration: some within our control, such as diet, water intake, lifestyle habits, skincare choices, and environmental exposure; and others that are less controllable, such as age or skin conditions like psoriasis and eczema. Studies have shown, for example, that transepidermal water loss (TEWL) is higher among participants with psoriasis compared with control participants.

In the next section, we’ll focus on the factors we can influence and share practical strategies to boost our skin’s hydration. By addressing these, we can also help buffer against those we have less control over, supporting healthier, more resilient skin in the long term.

Internal Hydration

Let us explore some of the controllable internal factors that impact skin hydration, both positive and negative:

1. Water Intake and Aquaporins:

Drinking water is one of the simplest yet most effective ways to support skin hydration. Whilst alone it might not completely prevent or treat skin dehydration, it provides the foundation our body needs to function optimally.

In practice, we recommend multiplying body weight in kilograms by 30-40mL water to determine a baseline water intake recommendation. If you are physically active then we may suggest a higher intake. 

Once consumed, water is transported through the bloodstream to skin cells. Here, Aquaporins; protein channels in cell membranes, play a vital role. Aquaporin-3 (AQP3) in particular helps to shuttle water and glycerol to the outer layers of the skin, ensuring they remain hydrated and supple.

When water intake is low, or Aquaporins aren’t functioning efficiently or are decreased; as occurs when we age, skin is more prone to dullness, tightness and fine lines. 

2. Hyaluronic Acid:

Often celebrated as a topical skincare ingredient, hyaluronic acid (HA) is also naturally produced by the body. It resides mainly in the skin’s dermis (middle layer) and has an extraordinary ability to bind water; up to 1000 times its own weight. This makes it essential for maintaining skin plumpness and elasticity. 

However, just like Aquaporins, the body’s natural supply of HA declines with age, leading to reduced hydration, loss of firmness, and visible fine lines. The good news is that we can support HA production internally through diet and lifestyle.

A nutrient-rich diet, combined with protection against oxidative stress, can help maintain the skin’s natural water-binding capacity. In particular, bone broth, magnesium-rich foods (such as nuts, seeds, and leafy greens), and phytoestrogen-rich foods (like edamame, tofu, and citrus fruits) can all play a role in supporting HA levels and, in turn, healthier, more hydrated skin.

3. High Protein Diets:

While protein is vital for collagen production, wound healing, and overall skin health, very high-protein diets; especially those lacking in dietary fibre from fruits, vegetables, and wholegrains, can sometimes compromise hydration. This is because excess protein increases the kidneys’ workload, leading to greater water excretion.

Over time, this may leave the skin less hydrated and more prone to dullness. Additionally, when protein is metabolised, the body produces nitrogen as a byproduct, which must be excreted through urine. This process increases the body’s water requirements, meaning high-protein diets naturally demand greater fluid intake to prevent dehydration.

In a study of athletes, the more protein participants consumed, the more concentrated their body fluids (including urine) became, indicating hypohydration. The high protein diet they consumed was ~30 percent of their total caloric intake, comparable or even less than many high protein diets people follow. Interestingly, many did not feel thirsty, despite their bodies being in a dehydrated state, a phenomenon sometimes referred to as “silent dehydration”.

Instead of focussing on protein alone, aim for balance: pair protein sources with hydrating, antioxidant-rich foods such as fresh vegetables, fruits, nuts, seeds and wholegrains, and incorporate plant-based protein sources like legumes, nuts and seeds.

As well, for those consuming higher levels of protein, it is important to offset this by increasing water and electrolyte intake despite potentially not experiencing increased thirst. This ensures you are supporting both skin structure and hydration simultaneously.

4. Tonicity:

Hydration is not just about how much water we drink, but also how well our body absorbs and retains it. This is where tonicity comes in, i.e. the balance of water and electrolytes (like sodium and potassium) in fluids.

If a solution is hypotonic (too diluted), water rushes into cells, causing them to swell. If it is hypertonic (too concentrated), water is pulled out of cells, leading to dehydration. The ideal state is isotonic, where the balance inside and outside the cells is the same. For example, drinking plain water (hypotonic) alone is still hydrating, but in very large amounts it can pass quickly through the system without being fully absorbed. 

In contrast, isotonic fluids with electrolytes (such as diluted fresh fruit juice, coconut water or water with a pinch of sea salt and lemon) enhances absorption and ensures hydration reaches the skin more effectively.

Similarly, hydrating foods that contain both water and minerals (like watermelon, cucumbers, citrus fruits, and lettuce) are highly efficient at delivering moisture to cells. So for effective hydration, a combination of plain water, isotonic fluids and hydrating foods is ideal.

5. Sodium, Caffeine and Alcohol:

Sodium plays a key role in hydration because it helps regulate fluid balance inside and outside our cells. When sodium levels are too high (for example, from a very salty diet), the blood becomes hypertonic (more concentrated with particles than the fluid inside our cells).

This imbalance draws water out of the cells, leading to cellular dehydration and skin that looks dull and lacklustre. On the other hand, extremely low sodium intake can also impair hydration by reducing the body’s ability to hold onto water.

The goal is balance: obtaining sodium from cooking and whole-food sources like celtic salt, miso and mineral-rich vegetables, while avoiding excessive intake from ultra-processed foods like crisps, crackers and fast food.

Caffeine, found in coffee, tea, and energy drinks, is often misunderstood. While it does have a mild diuretic effect, moderate intake (1-3 cups daily) still contributes to hydration and is unlikely to cause significant fluid loss in most people. In fact, tea and coffee contain polyphenols and antioxidants that can support skin health.

Problems arise with very high caffeine intake, which can increase fluid loss and contribute to dehydration if not balanced with water and mineral-rich fluids.

Alcohol, by contrast, is one of the strongest internal dehydrators. It inhibits the hormone vasopressin (also known as antidiuretic hormone), which normally helps the kidneys conserve water. Without it, the body excretes more fluids than it takes in, leading to dehydration, electrolyte imbalances, and visible skin effects such as puffiness, fine lines, and dullness. This is why alternating alcoholic drinks with water and including electrolytes can help lessen the impact.

External Hydration

1. Climate and Environment:

While internal hydration lays the foundation for healthy, resilient skin, the environment we live in has an equally powerful impact on how well our skin stays hydrated. The skin’s outer barrier (the stratum corneum) is constantly interacting with the air around us, meaning factors like weather, pollution, and even the climate-controlled spaces we spend time in can influence how much water is lost through the skin.

Hot, dry, or windy conditions accelerate transepidermal water loss (TEWL), stripping moisture from the skin’s surface and leaving it tight, flaky, and dehydrated. Cold winter air has a similar effect, often compounded by low humidity.

While we can’t change the weather, we can mitigate its impact by adapting our skincare routine to the season. For instance, layering hydrating serums under richer creams in the winter, or using lightweight, water-binding serums and gels in hot, dry climates.

Modern living adds another layer of challenge. Air-conditioning, central heating, and even frequent flying reduce humidity in the air, creating environments that “pull” moisture out of the skin. Spending long hours indoors under these conditions can leave skin chronically dehydrated, even if our water intake is adequate.

A few practical strategies to counteract this include using a humidifier at home or in the office, misting the skin with hydrating sprays during the day, and applying products with humectants (like glycerin or hyaluronic acid) to help the skin retain water.

2. Skincare Routines:

The products and routines we use on our skin can be just as influential on hydration as diet and environment. While many active ingredients deliver incredible benefits for concerns like acne, pigmentation, or ageing, they can also disrupt the skin barrier and increase transepidermal water loss (TEWL) if not used thoughtfully.

Ingredients such as retinoids, alpha hydroxy acids (AHAs), beta hydroxy acids (BHAs), and benzoyl peroxide speed up skin cell turnover or exfoliation. Overuse, or layering too many actives at once, can weaken the protective barrier and leave skin more vulnerable to moisture loss.

This is why spacing out actives, introducing them slowly, and pairing them with barrier-repairing products is crucial. If your skin feels tight, stings when applying products, or looks red and flaky, these are signs your barrier may be compromised and needs a gentler approach.

When the skin is stressed, simplicity is best. Stripping back your routine to the essentials: a gentle, non-foaming cleanser, a soothing moisturiser, and daily physical sunscreen, gives the barrier time to heal. During this phase, avoid harsh actives and instead lean into hydration and replenishment.

Ingredients like hyaluronic acid, glycerin, and aloe vera are humectants that draw water into the skin, helping to restore plumpness and elasticity. Niacinamide supports barrier repair while also improving hydration.

For those with dry skin or living in harsh climates, formulas rich in lipids and occlusives, such as ceramides, squalane, jojoba oil, or shea butter, can reduce water loss by creating a protective seal over the skin. This is especially helpful in winter or environments with low humidity, where the skin is more prone to dryness and dehydration.

The 6 Best Things We Can do to Hydrate Our Skin

TLDR? Fair enough, that was a lot of information and science, and in fairness, all we really need to know is what we can actually do to achieve hydrated skin. So here is a summary of the six best things we can do for hydrated and supple skin:

1. Drink Water and Isotonic Drinks:

Plain water is absolutely essential as it supports every cell in the body and travels into the skin through Aquaporins, the tiny “water channels” in cell membranes that regulate hydration.

But for optimal skin hydration, we can also add isotonic fluids which have electrolytes (like coconut water, diluted fresh juices, or water with a pinch of sea salt and lemon). Adding in isotonic drinks provides electrolytes that improve absorption and retention, helping hydration reach the skin more effectively.

2. Eat Hydrating Foods:

Foods that naturally combine water and minerals are some of the most efficient hydrators. Think watermelon, cucumber, citrus fruits, lettuce, and berries. They don’t just add fluid; they deliver electrolytes and antioxidants that help cells hold onto moisture more effectively. Incorporating these hydrating plant foods into our diet can boost our skin hydration. 

3. Minimise Dehydrating Substances:

Certain dietary and lifestyle factors can quietly drain our skin’s hydration. Excess sodium can create hypertonicity in body fluids, pulling water out of cells. Caffeine and alcohol act as mild diuretics, increasing water loss, especially if consumed in large amounts without adequate fluid replacement.

Minimising high sodium processed foods and alcohol, and ensuring low-moderate quantities of caffeine (<1-3 cups coffee/tea daily), is recommended.

In addition, very high protein diets can be quite dehydrating and can increase the body’s need for water, as more fluid is required to flush out nitrogen waste from protein metabolism.

If you eat a high-protein diet, it is especially important to balance it with increased fluid and electrolyte intake through water, isotonic fluids and hydrating fruits and vegetables.

4. Minimise Harsh Skincare Ingredients:

Powerful actives like retinoids, AHAs, BHAs, and benzoyl peroxide can be fantastic for skin health, but they can also compromise the barrier and increase transepidermal water loss (TEWL) if overused.

Keeping skincare routines balanced by introducing actives slowly, avoiding over-exfoliation, and always pairing them with barrier-repairing and hydrating products can help with maintaining hydrated skin whilst still getting the benefits from the actives.

5. Choose Hydrating Skincare Ingredients:

Topical hydration matters too and can mitigate the effects of skincare actives and harsh climates. Ingredients like hyaluronic acid, glycerin, aloe vera, and niacinamide act as humectants, drawing water into the skin.

For those needing extra protection against dryness and dehydration, look for moisturisers containing ingredients like ceramides, squalane, jojoba oil, or shea butter, which help lock in that moisture and support barrier function.

6. Consider the Environment:

We might not be able to control the weather, but we can protect our skin from it. Cold, dry air, wind, air conditioning, and heating all strip moisture from the skin.

We can counteract this by using a humidifier indoors, applying protective moisturisers before exposure, and wearing hydrating mists, serums and creams throughout the day if needed.