5 Warning Signs Your Vegan Diet Is Lacking Essential Nutrients

I’ve been cooking plant-based meals for a long time. Long enough to know that a vibrant vegan plate can be a celebration of flavor, color, and culture—and also, at times, a bit of a nutritional guessing game.

Because let’s be real: just removing animal products doesn’t automatically make a meal balanced. French fries and oat milk lattes? Technically vegan. But that doesn’t mean your body’s getting what it needs.

And I say this with love. Love for the lifestyle. Love for the animals and the planet. And love for the version of me that, years ago, proudly went vegan and then wondered why I was suddenly tired all the time.

Whether you’re new to plant-based living or you’ve been vegan longer than nutritional yeast has been trendy, it’s worth checking in. Here are five red flags that your body might be asking for more support—and what to do about it.

1. You’re tired, even when you’re sleeping enough

Let’s start with the big one: fatigue.

I’m not talking about that 3pm slump or the occasional post-brunch nap. I mean bone-deep exhaustion that lingers, even when you’re getting a full eight hours.

If this sounds familiar, low iron or vitamin B12 could be the culprits.

Iron helps deliver oxygen to your cells. Without enough of it, everything feels like a slog.

While plants like lentils, tofu, spinach, and pumpkin seeds are solid sources, they contain non-heme iron—which is less easily absorbed by the body than heme iron from animal products.

Pairing plant-based iron with vitamin C (like bell peppers or citrus) can boost absorption, but it still takes intention.

Then there’s B12—a vitamin produced by soil bacteria, not plants. In traditional diets, people got B12 from animal products or unwashed produce. Today’s sanitized food system means you’ll likely need to supplement.

Fix it: Get your iron and B12 levels checked annually. Supplement if needed. Fortified plant milks and cereals help, but for most people, a good-quality B12 supplement is non-negotiable.

2. Your hair feels thinner (or your nails break easily)

If your hairbrush is seeing more action than usual, or your nails snap like dry spaghetti, your diet might be low in protein or zinc.

Protein is a building block for hair, skin, and nails. And while beans, lentils, tofu, tempeh, quinoa, and nuts can meet your needs, the key is variety—not relying on peanut butter and oat milk to do the heavy lifting.

Zinc is another quiet hero. It supports everything from wound healing to healthy skin. You’ll find it in foods like chickpeas, cashews, and pumpkin seeds, but like iron, plant-based zinc is harder to absorb.

Fix it: Mix it up. Rotate your proteins, don’t skip meals, and consider a multivitamin with zinc if your plate is coming up short.

3. You’re constantly cold (even when it’s warm out)

Some people just run cold—that’s biology. But if you’re layering up in June while your friends are in tank tops, your thyroid might be trying to get your attention.

Your thyroid regulates metabolism, temperature, and energy levels. Iodine, selenium, and iron are all critical for thyroid health.

But here’s the catch: iodine can be tricky on a vegan diet. Most of it comes from iodized salt and seaweed, and too much or too little can throw things off.

Fix it: Switch to iodized salt (if you’re not already using it). Add nori or dulse to soups, salads, and bowls. And again—blood work is your friend. If you’ve been cold, sluggish, or moody for a while, ask your doctor about thyroid testing.

4. Your mood is all over the place

If you’re feeling more irritable than usual, or your emotions feel like a rollercoaster without brakes, your vegan diet might need a few adjustments.

Omega-3 fatty acids, particularly EPA and DHA, play a big role in brain health. But plant-based eaters often miss out on these because most plant sources (like chia, flax, and walnuts) provide ALA—a precursor that your body only partially converts to the active forms.

Low B12 and iron can also affect mood and cognition. And if you’re skipping meals or not eating enough overall, that blood sugar crash can stir up all kinds of emotional static.

Fix it: Consider an algae-based omega-3 supplement (look for ones that contain both EPA and DHA). Eat regularly, pair carbs with protein, and keep an eye on your micronutrients.

5. You’re bloated more often than not

Okay, this one’s awkward—but let’s talk digestion.

A sudden switch to a high-fiber vegan diet can shock your gut, especially if it’s short on variety. Over-reliance on soy, processed meat alternatives, or beans without proper prep can leave your belly feeling like a balloon.

Plus, let’s not forget about probiotics and prebiotics. A healthy gut loves fermented foods—like kimchi, miso, and plant-based yogurt—as well as fiber from fruits and veggies.

But it’s a balance. Too much of one thing, and your gut may revolt.

Fix it: Soak your beans before cooking. Ease into fiber-rich meals if you’re new to them. Try adding fermented foods slowly. And if the bloating persists, consider working with a plant-savvy dietitian to rule out intolerances or gut imbalances.

The big picture: Nourishment, not just ingredients

Going plant-based is a beautiful step toward a more compassionate and sustainable life. But compassion should include you, too.

Too often, we fall into the trap of assuming vegan = healthy by default. But a diet made of beige carbs and frozen vegan nuggets (we’ve all been there) isn’t going to cut it.

When I first went vegan, I relied heavily on what I knew how to cook: rice, beans, and sautéed greens. Solid staples, but I didn’t branch out.

It wasn’t until I started experimenting—with millet, mung beans, nutritional yeast, and tahini dressings—that I felt like my energy returned.

Now I approach my meals with a different question: How can I feed my body, not just fill it?

That shift has made all the difference.

Final thoughts: Small changes, big impact

You don’t need to overhaul your kitchen or order a dozen new supplements today. But you do need to listen—to your body, your mood, your energy. Those signals are feedback, not flaws.

If something feels off, don’t panic. Just pause. Ask questions. Make tweaks.

Start with bloodwork. Rotate your protein. Add fermented foods. Supplement where needed. Stay curious.

A thriving vegan diet isn’t about restriction—it’s about rhythm, flavor, and paying attention.

And when you get it right? You don’t just eat plants. You flourish with them.