4 Best Iron Supplements for Athletes [2025 Guide]

Pros:

• NSF Certified for Sport

• Sourced from Ferrochel® iron for maximum bioavailability

• Includes Vitamin C to further aid absorption + Vitamin B Complex to support energy production

• Good subscription discount

Cons:

• Price

I’ve tried my share of iron supplements over the years, and most of them have either upset my stomach or felt like a chore to take. Momentous Iron+ has been a different experience. The first thing I noticed was how gentle it is on digestion—no nausea or heaviness like I’ve had with cheaper tablets. That’s likely because it uses Ferrochel® iron, which is known for being easier to absorb and less harsh on the gut.

What I love most, though, is that this isn’t just iron. It’s combined with Vitamin C (to help your body actually absorb the iron you’re taking) and a full B-complex—the same vitamins that fuel energy metabolism and red blood cell production. As someone who enjoys longer workouts, I’ve felt the difference in how steady my energy feels during bigger training blocks. The creeping fatigue I used to chalk up to “just being tired” started to fade after a few weeks.

Another huge plus? It’s NSF Certified for Sport. That stamp matters because it means I don’t have to worry about contaminants or banned substances—something every competitive athlete should think about.

Of course, Momentous isn’t the cheapest option at $19.95 for 60 servings. If price is your main concern, there are less expensive bottles on the shelf. But for me, the combination of clean sourcing, effective formulation, and third-party certification justifies it.

In my experience, Momentous Iron+ is best for anyone who trains hard, sweats a lot, and wants to support oxygen transport and energy without worrying about what’s in their supplement. It’s become a quiet staple in my routine and is well worth trying for yourself. 

Thorne Iron Bisglycinate delivers 25 mg of elemental iron per capsule using Ferrochel® bisglycinate chelate, a form known for being highly absorbable and gentle on the stomach. The supplement is NSF Certified for Sport, giving competitive athletes confidence that it’s free from contaminants and banned substances.

Many users highlight that Thorne’s formula is noticeably easy to tolerate, even on an empty stomach, which is a common concern with other iron products that can cause nausea or constipation. Reviews frequently mention improved iron levels and reduced fatigue after consistent use.

At $15 for 60 servings, this is one of the more cost-effective iron supplements available—especially with free shipping and a 20% subscription discount. However, unlike some premium formulations, it doesn’t include supporting vitamins like vitamin C or a B-complex, meaning users who want to maximize iron absorption or support energy production may need to pair it with additional supplements.

Overall, Thorne Iron Bisglycinate is a straightforward, well-formulated option for anyone needing a reliable source of iron, particularly athletes who value third-party testing and a stomach-friendly dose at an affordable price point.

Active Iron is a high-potency iron supplement designed to improve absorption while minimizing the digestive discomfort often associated with traditional iron tablets. Using a patented formula that binds iron to a whey protein complex, the supplement is able to deliver iron more effectively to the small intestine. This targeted delivery has been clinically shown to improve iron levels by up to 94% in six weeks, with users frequently reporting noticeable reductions in fatigue.

The product is certified by Informed Sport, meaning every batch is screened for banned substances, making it a trusted choice for competitive athletes. It is also gluten-free and non-GMO, though it is not vegan due to its whey-derived formulation.

One of the drawbacks is that Active Iron does not include supporting nutrients like vitamin C or a B-complex, which are often paired with iron to enhance absorption and support energy metabolism. At $34.95 for 60 servings, it is also priced higher than many standard iron supplements and is distributed primarily through third-party retailers like Amazon, without subscription discounts or free shipping options.

Despite the higher cost, Active Iron stands out for its gentle, clinically supported formula and rigorous third-party testing, making it a strong option for athletes and individuals needing reliable iron support.

Gnarly Baseline Iron is a thoughtfully crafted, plant‑based iron supplement that delivers 25 mg of iron bisglycinate, a highly bioavailable non‑heme form known for its gentle effect on digestion and strong absorption. Designed with vegan and vegetarian athletes in mind, it includes 15 mg of vitamin C, 50 µg of methylcobalamin (Vitamin B₁₂), and 400 µg of natural L‑5 MTHF folate, all of which support iron absorption and red blood cell production.

It carries the prestigious NSF Certified for Sport certification, ensuring third‑party testing for contaminants and banned substances. It is also gluten‑free, GMO‑free, vegan, and made with minimal additional ingredients like vegetarian capsules and rice bran. A money‑back guarantee, free shipping on orders over $75, and a 20% subscription discount add practical value for repeat users.

Priced at $14.95 for 30 servings, Baseline Iron+ offers competitive affordability, though the cost per serving ($0.49) is higher relative to bulk alternatives. Overall, it stands out as a clean, hypoallergenic option with nutrient synergy tailored for endurance and plant-based athletes, while maintaining high quality and third-party validation.