Protein: The Building Block Your Hair Can’t Do Without
Hair is made almost entirely of keratin, a type of protein. If you’re not eating enough protein, your body will deprioritize hair growth to protect more essential functions. The result is diffuse shedding and slower regrowth.
Most adults need between 0.7 and 1 gram of protein per pound of body weight per day, and many people, particularly those who eat plant-forward diets or restrict calories, fall short without realizing it. Eggs, fish, chicken, legumes, and Greek yogurt are all strong, accessible sources.
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Iron: The Most Commonly Missed Deficiency
Iron deficiency is one of the most prevalent and underdiagnosed causes of hair loss, particularly in women. It affects the hair growth cycle directly, pushing follicles out of their active growth phase prematurely.
The tricky part is that standard iron panels often miss the problem. Ferritin, the protein that stores iron in the body, is the more relevant marker for hair loss, and it’s frequently left off routine lab orders. If you’re shedding excessively and also feel fatigued or foggy, requesting a ferritin test specifically is worth doing.
Red meat, leafy greens, lentils, and pumpkin seeds are good dietary sources. Pairing iron-rich foods with vitamin C significantly improves absorption.
We cover the iron and hair loss connection in depth in a dedicated post if you want to go deeper on this one.
Zinc: Quiet but Critical
Zinc plays a key role in protein synthesis and cell division, two processes that are essential for healthy hair growth. It also helps regulate androgen production, which matters because elevated androgens are a primary driver of pattern hair loss.
Zinc deficiency can cause hair thinning, a dry or flaky scalp, and slow healing. Oysters, pumpkin seeds, beef, and chickpeas are among the best dietary sources. Because zinc and iron compete for absorption, taking them as separate supplements at different times of day is worth knowing.
Biotin: The Most Talked About, the Most Misunderstood
Biotin (vitamin B7) is one of the most heavily marketed nutrients for hair growth, and the reason is legitimate, a true biotin deficiency does cause hair loss. But true deficiency is actually uncommon in people who eat a reasonably varied diet.
For most people with adequate biotin levels, supplementing more won’t produce the dramatic results the packaging suggests. If you are deficient, though, correcting it can make a real difference. Eggs, salmon, sweet potatoes, and nuts are reliable sources. If you’re taking a biotin supplement, it’s worth flagging to your doctor before any lab work, as high biotin levels can interfere with certain thyroid and hormone test results.
Vitamin D: Far More Important Than Most People Realize
Vitamin D receptors are found directly on hair follicles, and low vitamin D levels are meaningfully associated with hair loss, particularly in women. It’s also one of the most common deficiencies in the general population, especially for people who spend most of their time indoors.
If you haven’t had your vitamin D levels tested recently, it’s worth adding to your next panel. Supplementation is simple and can have a genuine impact on hair growth over time. We’ve written a dedicated post on the vitamin D and hair loss connection for anyone who wants the full picture. Shop our go-to Vitamin D3 supplements here!
Omega-3 Fatty Acids: For the Scalp Environment You Can’t See
Omega-3 fatty acids support scalp health by reducing inflammation and maintaining the skin barrier that your follicles depend on. A dry, inflamed scalp is not a hospitable environment for healthy hair growth, and chronic scalp inflammation is an underappreciated contributor to shedding.
Fatty fish such as salmon, sardines, and mackerel are the best sources. Flaxseeds, chia seeds, and walnuts provide plant-based omega-3s. For people who don’t eat much fish, an algae-based omega-3 supplement is a well-absorbed alternative.
B Vitamins: The Energy Your Follicles Run On
The B vitamin family, particularly B12, folate, and niacin, supports the energy production that hair follicles depend on to function. B12 deficiency is especially common among people who eat primarily plant-based diets, since B12 is found almost exclusively in animal products. Hair loss, persistent fatigue, and neurological changes are all potential signs.
If you’ve been plant-based for a while and haven’t checked your B12 recently, adding it to your next lab panel is a good idea. Shop our favorite B12 supplements here!
