Your Hair: A Reflection of What's Happening Inside

When people notice more shedding in the shower (over 100–150 hairs per day), thinning at the temples, a widening part, or hair that suddenly feels brittle and lifeless, their first instinct is often to look for a better shampoo or try a scalp treatment. While those can sometimes help, hair health is so much more than what’s happening on your scalp. Your hair is a living reflection of what’s happening inside your body.

Hair is deeply connected to your internal physiology.¹ Our hair follicles, the small, tube-like structures that live within the skin and produce hair, are especially sensitive to changes in the body, including nutrient imbalances and stress.¹ In many cases, the hair can be one of the first places we see signs that the body is under strain.

In other words: If your hair is changing, it may be worth asking not just, “What should I put on it?” but also “What is my body trying to tell me?”

Hair follicles require a steady supply of protein, calories, essential fats, vitamins, and minerals to stay in a healthy growth phase. When the body is experiencing nutrient gaps, whether from restrictive dieting, significant weight loss (including from GLP-1 use), inadequate protein intake, digestive issues, or increased nutrient demands, our hair can visibly change or shed more as a result. 

When the body is well nourished, more hair stays in the growth phase. But when nutrition is compromised, more follicles can shift prematurely into shedding or dormant phases. You can learn more about the hair growth cycle here.  

Hair is primarily made of keratin, a type of protein. For an average, healthy adult, an intake of about 0.4–0.7g of protein per kg of body weight per day is generally recommended.^1,2,3 For people on high-intensity physical programs like weight lifting, protein needs may be significantly higher compared to those who aren’t.² This is because the amino acids from the proteins get sent more to the muscles in those who work out harder, so less may be available for hair health,² which can result in a shortened anagen phase, increased shedding, and reduced hair strength.^1,2 

Working with a nutritionist or dietitian can help you determine individualized protein goals based on your activity level and lifestyle.  

Essential fatty acids like omega-3s and omega-6s also play a role in maintaining a healthy hair growth cycle. These fats are important components of cell membranes and help regulate cell signaling, both of which influence the function of hair follicles. They also help maintain the balance between the growth, dormant, and shedding phases of the hair cycle. Those who don’t get healthy fats regularly in their diets may experience an increased number of hair follicles stuck in the dormant or shedding phases, which can contribute to more thinning over time.¹

Foods that support healthy fat intake include^4,5:

Hair health can also be impacted by a number of vitamins and minerals, including iron, zinc, and B12.

Iron is essential for our hair. It allows the body to produce hemoglobin, a protein in red blood cells that carries oxygen to the hair follicles and throughout the entire body.¹ Iron is also necessary for DNA production. Since hair follicle cells are constantly dividing to help produce more hair, iron is required to allow for healthy hair to grow.¹ Gaps in iron intake can contribute to increased hair shedding, thinning, and slow growth.¹ 

Zinc is also critical for producing keratin, the main protein that makes up our hair.⁶ Low zinc has been associated with hair shedding, brittle hair, thinning, and slower growth.^1,6  

Vitamin B12 also supports hair health through its role in red blood cell production⁷ Healthy red blood cells deliver oxygen to the hair follicle so that it can produce energy and function properly.⁸ Research suggests that adequate B12 helps support a healthy hair growth cycle.⁷ When B12 levels are low, hair follicles may struggle to stay in the growth phase, increasing the likelihood of shedding.⁷

Hair shedding can result from nutrient gaps—but it can also happen from excess.

Vitamin A is a classic example. Vitamin A is important for healthy hair, but more isn’t always better. Getting too much vitamin A in its active form, called retinol, can actually lead to more hair shedding.⁹ On the other hand, beta-carotene, the plant-based form of vitamin A found in foods like carrots and sweet potatoes, doesn’t carry the same risks.⁹ That’s because your body only converts beta-carotene into the active form of vitamin A as needed. So while both are forms of vitamin A, retinol and beta-carotene affect hair health differently.⁹

Depending on your hair concerns and goals, your doctor may order a few tests to better assess your nutrient status and needs, including:

Stress is another major root cause of hair thinning. When we talk about stress, we don’t only mean emotional or psychological stress. Physiologic stressors like sleep deprivation, illness or infection, surgery or accidents, over-exercise without recovery, and blood-sugar instability all matter when it comes to hair health. 

One of the clearest ways stress affects hair is by disrupting the hair cycle. Under intense or ongoing stress, hair follicles are more likely to leave the growth phase earlier than they should and begin to shift into the dormant or shedding phases.¹ This is why many people notice more shedding 3–6 months after a major stressor.¹⁰   

Cortisol, one of the body’s main stress hormones, plays a major role in hair health. When under stress, the body activates a communication loop between the brain and the adrenal glands that releases cortisol to provide energy and focus to help handle potential threats.¹¹   

This cascade is helpful in short bursts. But when the system remains stuck on “overdrive” due to long-term stress or metabolic imbalances, it can begin to affect sensitive tissues, like the hair follicle.^1,11 High cortisol levels have been shown to interfere with the normal length of the growth phase, impair healthy hair development, and contribute to more thinning.¹¹ 

In simple terms: High stress can tell your body that hair health is not a priority right now.

If there’s one big takeaway here, it’s that your hair is not separate from the rest of your body. Hair is often a reflection of your internal environment, and when your hair starts changing, it may be a sign that your body is asking for support.

If you’re experiencing significant hair shedding (over 100–150 hairs per day), thinning, or slower growth, talk with your doctor and be sure to discuss these two foundational areas of hair health:

Stress management isn’t just about “relaxing more.” It’s a practice, like learning an instrument or building strength in the gym. Consistency matters more than perfection. Explore:

The key is building a repeatable routine that teaches your body how to spend more time in a regulated state. These practices become easier and more impactful the more often you do them, versus just reaching for them when you’re feeling overwhelmed. Nutrafol subscribers get complimentary access to the Headspace app for guided meditations, calming mindfulness practices, and additional stress management support. 

If your hair is thinning, shedding more than usual, becoming brittle, or simply not growing the way it used to, it may be worth zooming out and looking at the bigger picture. Sometimes, hair is the messenger. And often, the most effective hair support starts with the same foundations that guide the rest of your health.

For those who want more targeted support, Nutrafol Hair Growth Nutraceuticals can be a helpful addition, as they’re formulated to address common root causes of thinning, including nutrient gaps and stress. Nutrafol also offers booster options, which can be paired with Hair Growth Nutraceutical formulas to further support areas like gut microbiome health and nutrient absorption, energy and metabolism, and the body’s stress response. You can see our full product line here. 

At the end of the day, supporting your hair often means supporting your whole body. That includes nourishing your body with the right nutrients, managing stress, optimizing sleep, and addressing any underlying imbalances. When those foundations are in place, hair health tends to follow.