Researchers created a new laboratory test to check if folate supplements contain the right type of this important B vitamin. They found that folate comes in two forms—one your body can use and one it can’t. Some manufacturers accidentally mix both types together, which is a problem because supplements should only contain the useful form. Scientists tested 101 different supplements and found that 2 of them had too much of the useless form. This new test is faster and more accurate than older methods, helping make sure the supplements you buy actually contain what the label says.

The Quick Take

  • What they studied: Whether folate supplements contain the correct form of this B vitamin that your body can actually use, or if they’re contaminated with an unusable form
  • Who participated: 101 different dietary supplement samples from various prenatal vitamins and other supplements containing 5-MTHF (a type of folate)
  • Key finding: Out of 101 supplements tested, 2 samples had too much of the inactive form of folate—one had 1.39% and another had 50.28%, when the safe limit is 1% or less
  • What it means for you: If you take folate supplements, especially prenatal vitamins, this research suggests that most products are probably fine, but some may not contain exactly what they claim. This new test helps manufacturers and regulators catch these problems before supplements reach stores

The Research Details

Scientists developed a new laboratory technique called HPLC-MS (think of it as a super-precise microscope for molecules) to identify and measure two different forms of folate in supplements. They created a method that can separate these two forms in just 20 minutes, which is much faster than previous tests. The researchers carefully tested their new method to make sure it was accurate and reliable, following official guidelines for laboratory testing. Then they used this method to test 101 real supplement samples from stores to see if any contained the wrong type of folate or too much of the inactive form.

Folate is a crucial B vitamin, especially for pregnant women, because it helps prevent birth defects. However, folate exists in two mirror-image forms—one your body can use (L-form) and one it cannot (D-form). Some manufacturing processes accidentally create mixtures of both forms. This new test is important because it can quickly and accurately detect when supplements contain too much of the useless form, helping ensure product quality and safety.

This study was conducted in a single laboratory and followed strict international standards for validating new testing methods. The test showed excellent accuracy with a mathematical score (R²) greater than 0.99, meaning it reliably measures what it’s supposed to measure. The researchers tested the method’s ability to detect very small amounts of the inactive form and confirmed it works correctly in different types of supplement products (tablets, capsules, etc.). However, this is a method development study, not a study about health effects, so it focuses on laboratory accuracy rather than how these supplements affect people’s health.

What the Results Show

The new HPLC-MS test successfully separated and measured both forms of folate in supplements within 20 minutes. The test worked accurately across a wide range of folate amounts (from 1 to 160 micrograms per milliliter) and showed excellent precision. When applied to 101 real supplement samples, the test found that most supplements met quality standards. However, two samples exceeded the acceptable limit for the inactive form: one contained 1.39% (slightly over the 1% limit) and another contained a concerning 50.28% of the inactive form. This means that in the second sample, more than half of the folate was the type your body cannot use.

The test proved to be significantly faster than previously available methods for checking folate purity. It also worked reliably across different types of supplement products, including tablets, capsules, and powders. The method was sensitive enough to detect very small amounts of contamination, making it useful for quality control in manufacturing.

This new test is faster and more selective than older methods for measuring folate forms in supplements. Previous tests took longer and sometimes couldn’t clearly separate the two forms from other compounds in the supplement. This advancement means manufacturers and regulators now have a better tool to ensure product quality and catch problems more quickly.

This study only tested 101 samples, so we don’t know how common the problem is across all supplements on the market. The research focused on developing and validating the test method itself rather than studying whether the inactive form of folate causes health problems in people who take it. The study didn’t investigate why some supplements had contamination or whether certain manufacturers have more problems than others. Additionally, we don’t know if the two contaminated samples were isolated incidents or part of a larger pattern.

The Bottom Line

If you take folate supplements, especially prenatal vitamins, this research suggests most products are likely safe and accurate. However, this study supports the need for better quality control in the supplement industry. Consider buying from reputable manufacturers and look for products that have been tested by third-party organizations. If you’re pregnant or planning to become pregnant, talk to your doctor about which folate supplement is best for you (moderate confidence—based on manufacturing quality concerns identified in this study).

Pregnant women and those planning pregnancy should care about this research because folate is critical for fetal development. Supplement manufacturers and quality control teams should use this new test to ensure their products are pure. Regulatory agencies can use this method to monitor supplement quality. People taking folate supplements for other reasons (like those with certain genetic variations) should also be aware that product quality matters.

This research doesn’t address how long it takes to see health benefits from folate supplements—that depends on your individual needs and why you’re taking them. However, the new testing method can identify quality problems immediately, so manufacturers can catch and fix issues before supplements reach consumers.

Want to Apply This Research?

  • Track which folate supplement brands you use and note the lot numbers. When new quality test results become available, you can check if your specific product was tested and passed quality standards
  • Use the app to set a reminder to research your supplement brand’s quality certifications and third-party testing status. Document the manufacturer and batch number of supplements you purchase for future reference if quality issues arise
  • Create a long-term log of supplement brands and batches used, especially if pregnant or planning pregnancy. Check periodically for any recalls or quality alerts related to your specific products. Consider switching to brands that publish third-party testing results

This research describes a laboratory testing method for supplement quality, not a study about health effects in people. It does not provide medical advice about whether you should take folate supplements or which type is best for you. If you are pregnant, planning pregnancy, or have concerns about your folate intake, consult with your healthcare provider before starting or changing any supplement. While this study found quality issues in 2 out of 101 samples, it does not mean these supplements are unsafe—only that they may not contain exactly what the label claims. Always talk to your doctor before using any dietary supplement, especially if you have health conditions or take medications.