Nutrient Gaps That Frequently Catch New Vegans Off Guard

Why Nutrient Gaps Happen on a Vegan Diet

A vegan diet eliminates all animal-derived foods, which makes it rich in fiber, antioxidants, and many phytonutrients. But several vitamins and minerals are either absent from plant foods entirely or appear in forms the body absorbs less efficiently. Understanding these gaps isn't a reason to avoid veganism — it's a reason to plan thoughtfully.

If you're new to this way of eating, it helps to start with a solid nutrition foundation. Our beginner's guide to nutrition covers the core concepts before you layer in diet-specific considerations. And if you're still sorting out the difference between plant-based and vegan eating, the distinction actually matters when it comes to which nutrient rules apply to you.

The Six Nutrients New Vegans Should Know

Most nutrient shortfalls on a vegan diet trace back to the same short list. Here's what each one does, why plant-based sources fall short, and what to do about it.

Vitamin B12

B12 is produced by microorganisms and is found reliably only in animal products. It's the one supplement that nutrition researchers and registered dietitians broadly agree all vegans should take. Deficiency develops slowly but can cause irreversible nerve damage if left unaddressed. Fortified foods (certain plant milks, nutritional yeast, breakfast cereals) can contribute, but supplementation is the most dependable strategy.

Vitamin D

Most people get vitamin D through sun exposure and fatty fish — neither of which vegans can rely on consistently. D2 (ergocalciferol) is plant-derived and widely available as a supplement; D3 from lichen is another vegan-compatible option. Deficiency is common across the general population, not just among vegans.

Long-Chain Omega-3s (DHA and EPA)

Alpha-linolenic acid (ALA) from flaxseed, walnuts, and chia seeds is a plant-based omega-3, but the body converts only a small fraction of ALA into DHA and EPA — the forms linked to cardiovascular and brain health. Algae-based DHA/EPA supplements bypass this conversion problem entirely, since fish get their omega-3s from algae in the first place.

Iron

Plant foods contain non-heme iron, which is absorbed at a lower rate than the heme iron in meat. Absorption improves significantly when paired with vitamin C-rich foods. Cooking in cast iron and avoiding tea or coffee with meals can also help. See our overview of essential vitamins and minerals for more on how iron functions in the body.

Calcium

Dairy is the dominant calcium source in most American diets. Vegans can get calcium from fortified plant milks, tofu set with calcium sulfate, kale, bok choy, and white beans — but portion sizes need to be intentional. Oxalate-rich foods like spinach bind calcium and reduce how much the body actually absorbs.

Zinc and Iodine

Zinc from plant foods is less bioavailable due to phytates in grains and legumes. Soaking and sprouting these foods improves absorption. Iodine is trickier: it's concentrated in seafood and dairy, and most plant foods have very little. Iodized salt and seaweed are options, though seaweed content varies widely and unpredictably.

Practical Steps to Close the Gaps

Knowing the gaps is half the work. Here's how to address them practically without overhauling your entire diet:

• Get a baseline blood test. Before supplementing broadly, ask your healthcare provider to check B12, vitamin D, and iron levels. This tells you where you actually stand.
• Treat B12 as non-negotiable. This is the one supplement with near-universal agreement among nutrition professionals for vegans.
• Pair iron sources with vitamin C. Lentils with tomatoes, spinach with lemon juice — this pairing measurably improves absorption.
• Read labels on fortified foods. Not all plant milks are fortified equally. Check the nutrition facts for calcium and vitamin D content specifically.
• Consider an algae-based DHA/EPA supplement. This is especially relevant for people who were previously eating little fish.

A broader look at how diet patterns interact with nutrient intake is available in our article on plant-based eating strengths and gaps. And if you've found yourself chasing every new nutrition trend, it's worth recognizing where nutrition thinking commonly goes wrong.

This article is for general informational purposes only and is not a substitute for personalized medical or dietary advice. Speak with a registered dietitian or your healthcare provider before making significant dietary changes or starting supplements, especially if you have an existing health condition or are pregnant.