If you've hopped on the plant-based diet bandwagon and given up meat, dairy, and eggs, you're probably feeling like you've finally got the healthy-eating thing figured out. Unfortunately, as good as you may feel while following a vegetarian or vegan diet, you won't get enough of certain critical vitamins and minerals from eating plants alone. Two key supplements can go a long way toward filling those the gaps.

Vitamin B-12 and Iron

Some people on a strict vegan or vegetarian diet begin to feel foggy or sluggish, and there's a reasonable explanation for it. According to Douglas Kalman, Ph.D., R.D., and co-founder of the International Society of Sports Nutrition, the small deficiencies brought on by plant-based eating can lead to bigger issues long-term.

"From a cognitive or brain function standpoint, if you have insufficient intake of B-12 and insufficient intake of iron, it affects the health of your nerves. It affects cognition," he says.


Following a completely vegetarian or vegan diet eliminates the most prevalent sources of B-12 and iron, which are typically found in meat and dairy. While it may not be noticeable in the first few months of going plant-based, the effects over time can add up. As a sports nutritionist for a university, Kalman never neglects to quiz his athletes on their eating habits.

"I have 18 teams every season, every year, and I go through and ask, 'All right, who's a vegan? Who's a vegetarian? Who's a regular meat eater?'" he says. "That way, I know who needs a little bit of extra attention about how to pick foods."

There's nothing wrong with choosing to eat a vegetarian or vegan diet, and Kalman himself was a vegetarian for eight years. If you do decide to forgo meat and dairy, though, supplementing with B-12 and iron can help prevent deficiencies that can lead to mental sluggishness and low energy. Follow the labels for dosage and usage instructions.

If you're a lifter or other athlete, Kalman recommends educating yourself before limiting certain types of foods, so you know exactly which supplements you may need to fill the gap.

To hear more on Kalman's views on supplementation and athletic performance, listen to the Bodybuilding.com podcast Episode 43: Deep-Diving Sports Nutrition with Dr. Douglas Kalman, and for an in-depth education on what to eat to maximize your fitness goals, check out his educational program, Foundations of Fitness Nutrition.

Bodybuilding.com's Foundations of Fitness Nutrition Course
Bodybuilding.com's Foundations of Fitness Nutrition Course
This educational video series is designed to empower you in the area of fitness information where most people feel most helpless: how much, when, and what to eat to achieve their goals.

About the Author

Heather Eastman, NSCA-CPT

Heather Eastman, NSCA-CPT

Heather’s mission is to use her passion for fitness and her knowledge of training and nutrition to educate and motivate others to enjoy a healthy and active lifestyle.

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