Nutrient Library Methodology

Where the numbers come from

Every figure in the nutrient library — recommended daily amounts, tolerable upper limits, and the life-stage breakdowns behind both — comes from two public sources: the National Academies of Sciences, Engineering, and Medicine (NASEM) Dietary Reference Intake (DRI) tables, and the NIH Office of Dietary Supplements (ODS) fact sheets, which translate those tables into plain figures and explain what they mean in practice.

We don't maintain a second, separate copy of these numbers for the website. This library is generated from src/configin the Tavita mobile app — the exact configuration that decides what the app tells you about your own intake. If a number here looks off, it's off in the app too, and we'd want to know.

How it was verified

The full set of 33 nutrients was independently re-verified by blind re-derivation on August 9, 2026 — each recommended amount, upper limit, and basis was checked back against the underlying NASEM and NIH source tables without reference to the app's existing values, then reconciled against them. This page will note the date of the next re-verification pass when one happens.

How to read an upper limit

Not every upper limit means the same thing, and treating them as interchangeable is where a lot of supplement advice goes wrong. Three distinctions matter:

• Total vs. supplemental basis.Most upper limits count everything you take in — food and supplements combined. A few (magnesium, niacin, vitamin E) count only what comes from supplements. That's why, for example, magnesium's upper limit is a smaller number than its recommended daily amount: food magnesium is essentially unlimited by this rule, but the concentrated dose in a supplement isn't.
• What the limit is measured against.A handful of nutrients have a recommended amount and an upper limit that are written against different quantities entirely. Vitamin A's recommended amount includes plant carotenoids, but its upper limit applies only to preformed retinol. Folate's recommended amount is measured in Dietary Folate Equivalents; its upper limit is measured in synthetic folic acid. We label this explicitly next to every affected number rather than letting the units imply they're the same thing.
• A ceiling instead of a target. Sodium is the one nutrient in this library where the reference number is a maximum to stay under, not an amount to aim for. We never show it with a fill-to-100% framing, because reaching 100% of a ceiling is the failure state, not the goal.

Two of these are genuinely unsettled at the source, and we would rather say so than present a clean answer we can't support. For niacin, the NIH Office of Dietary Supplements describes the upper limit as applying only to supplemental niacin, while the underlying NASEM footnote extends it to synthetic niacin from supplements, fortified foods, or both. We follow the ODS reading. For vitamin D, no source we could find states whether its upper limit covers food as well as supplements; total intake is the reasonable default and matches how the framework treats every limit without an explicit exception, but that is our inference, not a published statement.

A few nutrients (vitamin K2, lutein and zeaxanthin, EPA, DHA, creatine) have no established recommended amount or upper limit at all — the evidence base isn't there yet for NASEM to set one. We say that plainly on those pages instead of inventing a number or hiding the section.

What this is not

Tavita OPC is a software company, not a medical provider. Nothing on this site or in the app is medical advice, and none of these pages were written or reviewed by a credentialed clinician acting in that capacity — the byline throughout is Tavita, the organization, not an invented author or reviewer. The figures are drawn faithfully from NIH and NASEM public references, but applying them to your own health, medications, or condition is a conversation for you and your clinician.

If you're looking for how Tavita, the app, uses these same numbers day to day — logging your intake, warning before a limit, and accounting for whether a limit is total or supplemental — that's covered on each nutrient's own page under “How Tavita handles this.”