What nutritionists wish new vegans knew about supplements (before it’s too late)

When I first went vegan, I thought I had it all figured out. I meal-prepped roasted veggie bowls, swapped out my whey protein for a pea-based one, and even learned how to make cashew queso that my roommates suspiciously liked.

I felt great—clean, light, and weirdly virtuous. That lasted about six weeks.

Then came the fog. Mental fog. Physical fatigue. The kind where getting out of bed feels like a full-body negotiation. I started sleeping more but feeling worse.

I snapped at people in line at the grocery store, which is wildly out of character for me. I thought I was just “adjusting.” It turns out I was running low on a few essential nutrients—some of which my body had quietly been stockpiling from my pre-vegan life, and some of which I’d never been getting enough of in the first place.

The twist?

My meals looked healthy. But the reality was, they weren’t giving me everything I needed.

I’m not telling you this to scare you. I’m telling you because, according to registered dietitians and nutrition researchers, this is extremely common. And most new vegans don’t learn about it until their bodies are already sending distress signals.

The myth of the “perfect vegan plate”

Here’s what I believed when I started:

If I eat enough variety—leafy greens, legumes, nuts, seeds, grains—I’ll get everything I need.

That’s the dream, right?

A rainbow plate that covers all your bases.

The truth is: some nutrients are hard to get from plants alone, no matter how well you eat. And some take time to show deficiencies. You might feel fine now but start noticing subtle changes weeks or months later—low energy, dry skin, poor focus, or weirdly intense cravings.

So let’s talk about the supplements most nutritionists wish you’d start thinking about before your body starts whispering (or yelling) for help.

1. Vitamin B12 – The non-negotiable

If you take nothing else from this article, take B12 seriously.

What it does: B12 is essential for red blood cell formation, nerve function, and DNA synthesis.

Why vegans miss it: B12 is made by bacteria—not plants or animals. Animals store it in their tissues after eating bacteria-laden soil or feed. Most modern humans (and livestock) don’t get B12 naturally anymore — it’s supplemented into animal feed. So unless you’re eating fortified foods or taking a supplement, you’re probably not getting enough.

What deficiency feels like: fatigue, brain fog, numbness or tingling in hands and feet, mood changes, even irreversible nerve damage if left untreated.

What experts say:
The National Institutes of Health recommends 2.4 mcg daily for adults. Many dietitians recommend a daily supplement of 25–100 mcg, or a weekly dose of 1,000–2,500 mcg.

You can get B12 from fortified plant milks, cereals, and nutritional yeast—but not from seaweed, mushrooms, or spirulina (despite what TikTok says).

Best practice: Take a sublingual B12 supplement (methylcobalamin or cyanocobalamin), especially if you’ve been vegan for more than a month.

2. Iron – You might be eating enough, but still not absorbing it

What it does: Iron helps your body make hemoglobin, which carries oxygen in the blood.

Why vegans need to be strategic: Plants contain non-heme iron, which is less easily absorbed than the heme iron found in meat. This means you may need up to 1.8x more iron from plant sources to meet your needs.

What deficiency feels like: fatigue, shortness of breath, brittle nails, headaches, pale skin.

What helps:

• Pairing iron with vitamin C (like bell peppers, citrus, or strawberries) increases absorption.

• Avoiding coffee and tea with meals (they contain tannins that block iron uptake).

• Cooking in cast-iron pans can actually add small amounts of iron to your food.

Supplements: You don’t have to supplement if your iron levels are fine and you’re eating lentils, tofu, chickpeas, and spinach regularly—but many vegans (especially menstruating women and athletes) benefit from tracking their ferritin levels and supplementing as needed.

Pro tip: Too much iron can be harmful, so test before you take high-dose iron pills.

3. Omega-3 fatty acids – Brain food you don’t want to skip

What it does: Omega-3s reduce inflammation, support brain and heart health, and may even improve mood and cognition.

Why vegans fall short: The essential omega-3s EPA and DHA are found primarily in fatty fish like salmon and sardines. Plant sources like flaxseed, chia seeds, and walnuts provide ALA, which your body can convert into EPA and DHA—but the conversion rate is extremely low (often under 10%).

What deficiency feels like: dry skin, fatigue, poor memory, eye problems, joint pain.

What nutritionists recommend: Consider taking an algae-based omega-3 supplement—a direct plant-friendly source of EPA and DHA without needing fish oil. One daily capsule is often enough to fill the gap.

4. Vitamin D – The sunshine vitamin that’s hard to come by

What it does: Vitamin D regulates calcium absorption, supports immune function, and affects mood and muscle function.

Why it’s tricky: Vitamin D isn’t easy to get from food—vegan or not. Sunlight helps your skin produce it, but depending on where you live (cloudy winters, indoor lifestyle), you may not make enough. Vegan sources are limited to fortified foods like plant milks and cereals.

What deficiency feels like: fatigue, low mood, frequent illness, muscle aches, or bone pain.

Recommendation:

• Get your levels tested—many people are low and don’t know it.

• Supplement with vitamin D2 or vegan-friendly D3 (made from lichen). Dosages range from 600 to 2,000 IU daily depending on your levels and exposure.

5. Iodine – The overlooked one

What it does: Iodine is vital for thyroid function, which regulates metabolism and energy.

Why vegans often miss it: Iodine is found in dairy, seafood, and iodized salt. If you avoid all three (and use fancy pink Himalayan salt instead of iodized), you might be missing this critical nutrient.

What deficiency feels like: weight gain, fatigue, sensitivity to cold, and even goiter in extreme cases.

Fix it:

• Use iodized salt for cooking.

• Eat sea vegetables (like nori or wakame) 1–2 times a week, but be cautious—some varieties, like kelp, have too much iodine.

• Supplement in microdoses if needed (150 mcg is standard).

A vegan diet needs support, not shame

Here’s what I wish someone had told me early on: needing supplements doesn’t mean you’re failing.

It means you’re human. And it means you’re being proactive.

Veganism can be incredible for your health, the planet, and animals—but it’s not magic. It still requires attention, intention, and (yes) a few bottles in your cabinet.

You don’t need to fear deficiencies—but you also shouldn’t ignore them. Most supplements cost less than a couple lattes per month and can make a huge difference in how you feel.

What to do next

If you’re new to veganism or just want to feel your best on a mostly plant-based diet, here’s a quick plan:

Step 1: Get tested

Check your levels for B12, iron (ferritin), vitamin D, and thyroid markers (like TSH and T3). Many labs now offer vegan-focused blood panels.

Step 2: Find a trusted brand

Look for third-party tested supplements—ideally certified vegan and free from fillers. Algae-based omega-3s, methylcobalamin B12, and lichen-based D3 are great places to start.

Step 3: Create a system

Don’t rely on memory. Set reminders. Use a pill organizer. Blend powders into smoothies. Make it easy and habitual.

Being vegan doesn’t mean ignoring your body’s needs—it means listening to them more closely.

So take your supplements. Eat your lentils. And know that you’re not just surviving this lifestyle — you’re learning how to thrive in it.

Because nothing says “plant-powered” like a brain that works, a body that moves, and a heart that keeps showing up for your values—fully nourished, inside and out.