When it comes to diet and hair health, most people know to get vitamin something, consume a mineral or so (usually zinc), and skip the polonium.

But, there’s a little more to it than most people realize:

Foods For & Against

Researchers (Dr. Beatriz Teixeira et al.) investigated, by means of a huge literature review (taking data from 17 observational studies, with 613,320 participants, of whom, mostly women), what things actually matter the most, for and against.

First, what not to do:

Foods and drinks that worsen hair loss include sugar-sweetened beverages, and even more strongly, alcohol:

• Sugar spikes cause inflammation that disrupts hair cycles
• Alcohol contributes in a whole stack of ways, both directly and indirectly, including:
  • nutrient deficiencies (hypothesis: due to people drinking a higher portion of their calories in alcohol rather than eating nutritious food)
  • poor absorption of nutrients (because alcohol causes the body to do almost everything worse, and especially messes with the gut, and not in a good way—one might struggle to spell “dysbiosis” when one’s had a tipple or two too many, but suffice it to say, alcohol causes the gut microbiome to swing wildly in the direction of Bad Things™, including C. albicans, also called simply Candida, the fungus which puts its roots through your intestinal walls, making holes there giving you leaky gut syndrome, and also interfaces with your nervous system via its roots that escape the gut and access the vagus nerve, and thus gives you cravings for more alcohol/sugar/flour, by sending false signals up to your brain) (we’re not exaggerating, check out the papers we cited in the relevant section of this article on gut health)
  • liver stress (because that’s where alcohol is metabolized, and our liver is not supposed to have to do that much work)
  • poor sleep (because of how it disrupts brain function, including while sleeping, at which time the brain’s job is normally “restore this” and it can’t do that correctly while impaired)
  • systemic inflammation (because of the combination of the above plus the fact that the alcohol itself is toxic, and even when metabolized, produces sugars that also worsen inflammation)

Now, some things most people know about:

Zinc and biotin (vitamin B7) deficiencies can cause thinning; adults need 30 μg vitamin B7 daily from foods like seeds, nuts, and sweet potatoes (to pick some out from the paper; there are plenty more options, of course). The researchers concluded that beyond that, extra supplementation is unlikely to help without deficiency.

Now, into lesser-known things:

Insufficient protein can trigger shedding; the researchers suggest about 0.5 g per pound of body weight daily, which is a very normal recommendation. We wrote about this more here: How Much Protein Do We Need, Really?

On which note, the researchers also tentatively recommend considering collagen, but note that while it seems entirely reasonable that it should help, the actual science is mostly not there for it yet (i.e. mostly hasn’t been done). Most collagen RCTs have been about skin health or joint health; less about hair. For more on that though, do see our research review on this: We Are Such Stuff As Fish Are Made Of

And if you are vegetarian/vegan? Worry not, because you can simply enjoy The Best Foods For Collagen Production, picking the vegetarian/vegan options in each category as applicable.

And as for other supplements of note:

• Persimmon leaf: linked to better hair density and thickness through antioxidants like quercetin that improve scalp blood flow; available as tea or supplements.
• Pumpkin seed oil: in a study of men with male pattern baldness, 400 mg daily for 24 weeks led to greater growth, likely by reducing DHT, the hair-thinning hormone (it does more things than that, but that’s what’s relevant here—actually, while we’re on this, let’s note for the record that while DHT thins head hair, it increases body hair, which for many people isn’t a combination they’re hoping for)
• Vitamin D: five studies found higher levels protective against hair loss; a suggested dose is 2,000 IU daily, though excess carries toxicity risk, so do keep within the recommended bounds (and double-check what other supplements have “plus vitamin D” tagged on, and/or foods “fortified with vitamin D”).
• Iron: supplementation improved growth in women; absorption is best when paired with vitamin C; dietary sources include spinach, lentils, and almonds. See also: The Iron Dilemma: Factors To Consider

Finally, in the category of specific foods that were mostly strongly associated with healthy hair growth, the researchers highlighted:

• Cruciferous vegetables (e.g. broccoli, cauliflower, kale, sprouts, etc) likely due to antioxidant and anti-inflammatory phytochemicals, and especially sulforaphane.
• Soy products (especially edamame & tofu, i.e., the least-processed of soy products) likely due to the top-tier amino acid profile, plus that while the phytoestrogens can’t be used as estrogens in the body (not compatible), they can be broken down and the “ingredients” used to produce your own estrogen, if (and only* if) you have working ovaries.
  • *Ok, so that was technically a lie; if you have working testes, then these can and do also produce estrogen, but in truly truly tiny amounts, and more than counterbalanced by the testosterone they produce. We wrote a bit about the science of ovaries and testes doing each other’s jobs, here. So if you are a reader with working testes rather than ovaries, then be aware: you could not physically eat enough soy to cause them to crank out enough estrogen to make the slightest change to your hair or any other part of your body. So our original statement stands, for all practical purposes: soy products will only increase your E levels if you have working ovaries to produce the E in question.

You can read the paper in full, here: Assessing the relationship between dietary factors and hair health: A systematic review

Want to learn more?

If you want to get very serious about it, you might want to consider: Hair-Loss Remedies, By Science

And/or if you want to go a drug-free route but without relying solely on diet, then check out: Gentler Hair Health Options

Take care!