Hair Health From the Inside Out
Hair health and struggles are topics that I find come up in many different conversations and something I get asked about fairly frequently. Because of that, I wanted to write up a little mini-blog post on some of the things to consider when supporting healthy hair.
Spoiler alert: it isn’t just about what you put on your hair.
Hair growth reflects what is happening inside the body. Nutrition, digestion, hormones, stress levels, and overall metabolic health all play important roles in the health of our hair follicles.
Understanding some of the basic biology behind hair growth can help us focus on the foundational factors that support healthy hair, rather than chasing quick fixes or miracle products.
Nutrients, Absorption, and the Hair Growth Cycle
Hair health is influenced by many factors including nutrition, hormones, stress levels, and overall metabolic health. Because hair follicles are among the most metabolically active cells in the body, they are often one of the first places the body shows signs of nutrient depletion, hormonal shifts, or physiological stress.
Hair shedding can occur during many stages of life. Illness, rapid weight loss, hormonal changes, chronic stress, postpartum recovery, and nutrient deficiencies can all influence the hair growth cycle.
Understanding the underlying biology can help us focus on the foundational factors that support healthy hair growth.
Understanding the Hair Growth Cycle
To understand why hair shedding happens, it helps to first understand how hair normally grows. Hair does not grow continuously. Each strand follows a repeating cycle of growth, transition, and rest.
Hair Growth Cycle Overview
| Phase | What Happens | Typical Duration |
|---|---|---|
| Anagen | Active hair growth phase | 2–7 years |
| Catagen | Transition phase where growth stops | 2–3 weeks |
| Telogen | Resting phase before shedding | ~3 months |
Most of our hair is normally in the anagen (growth) phase at any given time.
Hair shedding often occurs when a larger number of hairs move into the telogen phase simultaneously. This can happen during periods of illness, emotional stress, hormonal shifts, or nutrient depletion.
In many cases, the follicles themselves are not damaged. They are simply resetting their growth cycle, and new growth will begin again once things stabilize.
Why Hair Loss Often Appears Months Later
One confusing aspect of hair shedding is that it often appears several months after the trigger.
This delay happens because hair follicles enter the resting phase first, and the shedding occurs later when that phase ends.
Nutrients That Support Hair Growth
Because hair follicles are highly active cells, they rely on a steady supply of oxygen, amino acids, minerals, and vitamins to produce healthy strands.
Key Nutrients for Hair Follicle Health
| Nutrient | Why It Matters | Food Sources |
|---|---|---|
| Iron | Supports oxygen delivery to hair follicles | Red meat, liver, lentils, spinach |
| Zinc | Supports follicle repair and keratin formation | Oysters, beef, pumpkin seeds |
| B Vitamins | Support energy metabolism and cell division | Eggs, meat, leafy greens |
| Vitamin D | Helps regulate hair follicle cycling | Sunlight, fatty fish |
| Protein | Provides amino acids used to build keratin | Meat, eggs, dairy, legumes |
| Omega-3 fats | Support scalp and follicle health | Fish, walnuts, flax |
| Iodine | Supports thyroid hormone production | Sea vegetables, seafood, dairy |
| Selenium | Supports thyroid function and antioxidant protection | Brazil nuts, seafood, eggs |
Iron deserves special attention because low iron stores are one of the most common contributors to hair shedding in women, particularly after pregnancy or during times of increased physiological demand.
Thyroid health also plays an important role in hair growth. Minerals such as iodine and selenium help support normal thyroid hormone production, which influences metabolism and hair follicle activity.
However, simply consuming nutrients is only part of the equation.
Absorption Matters Just as Much as Intake
One important concept that is often overlooked is that taking nutrients is not the same as absorbing and assimilating them.
For nutrients to reach hair follicles, they must first be properly digested and absorbed through the digestive system.
Factors That Influence Nutrient Absorption
| Factor | Why It Matters |
|---|---|
| Stomach acid | Helps break down protein and absorb minerals like iron and zinc |
| Gut health | Healthy intestinal lining improves nutrient uptake |
| Adequate protein intake | Amino acids are required for hair structure |
| Blood sugar balance | Stable metabolism supports healthy hair cycling |
| Stress and sleep | Elevated stress hormones can shift hairs into the shedding phase |
For example, iron absorption improves when paired with vitamin C, while substances like coffee, tea, and calcium can reduce iron absorption when consumed at the same time.
When it comes to B vitamins, I often suggest methylated forms, as they are generally more bioavailable and some people have genetic variations that make it harder for the body to convert synthetic forms such as folic acid into their active forms.
Balanced meals and whole food nutrition are often more effective than relying on isolated supplements alone.
Common Causes of Hair Shedding
Hair shedding is usually influenced by multiple factors rather than a single cause.
Common Contributors to Hair Loss
| Category | Examples |
|---|---|
| Hormonal changes | Postpartum shifts, thyroid imbalance, menopause |
| Nutrient depletion | Low iron, zinc, vitamin D |
| Physiological stress | Illness, surgery, emotional stress |
| Dietary factors | Low protein intake, rapid weight loss |
| Inflammation | Scalp conditions or systemic inflammation |
| Medications | Chemotherapy, some antidepressants, certain blood pressure medications |
Certain medications can influence hair growth cycles by pushing more hairs into the telogen (shedding) phase. Chemotherapy is the most well-known example, but some antidepressants and other medications can also contribute to hair shedding.
Identifying the underlying cause often requires looking at overall health patterns, not just hair itself.
Lab Markers Often Evaluated in Persistent Hair Loss
When hair shedding persists for several months, it can be helpful to evaluate underlying physiology through lab testing. These markers can help identify nutrient deficiencies, hormonal shifts, or metabolic stress that may influence hair growth.
Common Lab Markers Considered
| Marker | Why It Matters |
|---|---|
| Ferritin | Reflects iron storage levels. Low ferritin is strongly associated with hair shedding. |
| CBC (Complete Blood Count) | Helps evaluate anemia and oxygen delivery to tissues. |
| Vitamin D (25-OH) | Vitamin D receptors help regulate hair follicle cycling. |
| Vitamin B12 | Supports red blood cell formation and oxygen transport. |
| Thyroid Panel (TSH, Free T4, Free T3) | Thyroid hormones strongly influence hair growth cycles. |
| Zinc | Important for follicle repair and keratin production. |
| Folate | Supports cell division and red blood cell production. |
| Iron Panel | Helps clarify iron status beyond ferritin alone. |
Ferritin is one of the most commonly overlooked markers. Many laboratories consider ferritin levels below 30 ng/mL technically deficient, but some clinicians prefer levels closer to 40–70 ng/mL when evaluating hair shedding.
Common Hair Loss Myths
Hair loss is an area where a lot of misinformation circulates online. Understanding a few common misconceptions can help people avoid unnecessary worry or expensive products that don’t address the underlying issue.
Hair Loss Myths vs Reality
| Myth | What Research Suggests |
|---|---|
| Hair loss is usually caused by biotin deficiency | True biotin deficiency is rare. Most shedding relates to hormones, stress, or mineral deficiencies such as iron. |
| Hats cause baldness | Wearing hats does not cut off circulation to hair follicles. |
| Washing or brushing hair causes hair loss | Washing or brushing simply reveals hairs already in the shedding phase. |
| Cutting hair frequently makes it grow faster | Hair growth occurs at the follicle level, not at the ends of the hair. We don't function like plants that need pruning to promote growth ;) |
| Hair loss always means permanent damage | Many types of hair shedding are temporary and reversible. |
| Hair loss is always genetic | Genetics can play a role, but many cases are related to temporary physiological stress. |
A Note on Postpartum Hair Loss
Many women experience noticeable hair shedding several months after pregnancy (myself included).
During pregnancy, higher estrogen levels keep hair in the growth phase longer than usual. After birth, hormone levels shift and many hairs move into the resting phase at the same time.
A few months later, those resting hairs shed. This process is called telogen effluvium (the process we are talking about throughout this blog).
Although it can feel dramatic, this type of shedding is usually temporary as the hair growth cycle resets and the body gradually replenishes nutrients used during pregnancy and breastfeeding.
Takeaway
Hair health is rarely about a single supplement or product. Instead, it reflects the body’s overall state of nourishment, digestion, hormonal balance, and recovery.
Supporting healthy hair growth often begins with foundational habits such as:
• balanced meals with adequate protein
• mineral-rich foods and teas
• good digestion and nutrient absorption
• adequate rest and stress recovery
When the body is properly nourished and supported, healthy hair growth often follows. Hair is often a reflection of what is happening beneath the surface in the body, which is why supporting overall health is one of the most effective ways to support healthy hair over time.
Comment
Hair is so fascinating! It really is like a report card about your body and how it’s doing on the inside.