Vitamin B12

Vitamin B12 helps maintain the insulating sheath around nerve fibres. When it is deficient, the effects can include fatigue, difficulty concentrating, numbness and problems with balance; nerve symptoms can appear even without anemia. These are reasons to interpret a low result alongside symptoms, rather than treating it as a minor shortfall in a vitamin panel. NIH ODS; NICE NG239.

Low results are widespread in the employees and covered family members tested through Loop. Nearly seven in ten B12 reports fall below this report's comparison cutoff, and the two lower bands are almost equally large: one below 200 pg/mL and one from 200 to below 300. That second group matters too. A borderline result can need further assessment, and treatment depends on why B12 is low—food intake and the body's ability to absorb it are different questions.

Seven in ten reports came back below the cutoff#

Loop ran vitamin B12 on 6,192 of the 11,427 laboratory reports in this year's window. 69.6% came back below 300 pg/mL — the level this report uses to call a B12 result low, and the same cutoff WHI 2025 used, where 68.2% of 1,399 reports fell below it. The share is 1.4 percentage points higher, on a sample 4.4 times the size.

The two bands under the cutoff are almost exactly the same size: 2,138 reports fall below 200 and 4,308 below 300 — 34.5% and 69.6% of the 6,192. Because fewer than half the reports are below 200 but more than half are below 300, the midpoint of this distribution sits inside the band from 200 to below 300 pg/mL. Fewer than one report in three — 1,884, or 30.4% — came back at 300 pg/mL or above. This is not a small deficient tail dragging down an otherwise healthy set of results. It is where the bulk of the results are.

Both of those boundaries are this report's own. 300 pg/mL is the cutoff it uses to call a result low, matching WHI 2025 so the two editions can be compared; below 200 is the band it calls deficient. Other conventions differ: NICE's 2024 guidance sets its own total-B12 boundaries at 180 and 350 ng/L — the same unit under a different name — permits validated local laboratory thresholds, and sorts results into confirmed, indeterminate and unlikely deficiency (NICE NG239, 2024). The borderline band is not an empty category between two real ones: the NIH Office of Dietary Supplements describes 200–300 pg/mL as "low or marginal vitamin B12 status", and says that where a serum result falls between 150 and 399 pg/mL, serum methylmalonic acid should be checked to help confirm a diagnosis (NIH ODS, 2025). A result near either boundary is settled against symptoms and, where the picture is unclear, that second test. A share below a threshold is not a count of diagnosed patients, and this page does not treat it as one.

For scale outside this workforce: a north-Indian study found 74.9% of a 267-person sample below 300 pg/mL, and 47.2% below 200 (Singla et al., Indian Journal of Endocrinology and Metabolism, 2019). Those 267 records come from commercial preventive-health-checkup camps run in one tier-3 city, Jind in Haryana, between 2016 and 2018; their mean age is 48.8, and the authors note that people who turn up for a paid check "may be more health conscious than general population". Counting 200 to 300 as borderline, the same authors put about a quarter of that sample in the sufficient range. It is a differently drawn sample so it is not a direct workforce benchmark. Both samples nevertheless show the same broad finding: the bulk of results below the line, with many results in both low bands.

The 6,192 results include 2,221 covered-family reports. Methodology.

The 20s test worst, and the share falls with every older band#

Three in four reports from people in their 20s are below the cutoff, and the share falls in every successive adult band, ending nearly 25 points lower at 60 and above. Blood sugar in this report runs the other way, worsening across each of those same adult bands. B12 does not. WHI 2025 found the same direction on its own age bands: worst in the youngest group tested, best in the oldest.

The adult bands contain 6,125 reports. A further 66 reports are from people under 20, with 54.5% below the cutoff, and one has no age recorded.

The direction runs against the clinical background, which is what makes it interesting. One of the common causes of poor B12 absorption gets more likely with age, not less: atrophic gastritis, which reduces both stomach acid and intrinsic factor, affects around 2% of adults generally but 8–9% of those over 65 (NIH ODS, 2025). That is general clinical knowledge, not an account of these reports. This report does not measure why its own oldest band tests best.

Men test worse than women by 14.6 points#

Three in four reports from men fall below the cutoff, against three in five from women — a gap of 14.6 percentage points. It runs opposite to anemia, where women carry the burden. B12 deficiency can cause anemia; that is a general clinical fact, and this report does not identify the cause of any anemia case in it.

WHI 2025 found the difference running the same way, in all five cities where it published a sex split. It measured that on its deficiency cutoff of 200 pg/mL rather than the 300 used here, so what has recurred is the direction, not the size.

Bengaluru tests worst of the five largest reporting areas#

Bengaluru leads these five by a wide margin: 78.8% of its 1,723 reports are below the cutoff, more than 18 points above Hyderabad and 11 clear of the next area. Delhi NCR and Pune are level at 67.7%. Bengaluru also tested worst in WHI 2025, when it was reported as Bangalore and led the four cities that edition ranked.

Diet affects B12 intake, but these results do not establish why the cities differ. Dietary preference is collected in the workforce nutrition survey, the B12 results come from laboratory reports, and the two datasets are not linked at the individual level, so a city label on one is not a statement about the people behind the other.

These are the five largest pincode-based reporting areas. Comparisons with 2025 are not city health trends.

Employees test worse than covered family members by 12.0 points#

Just under three in four reports from employees fall below the cutoff, against three in five from covered family members — a gap of 12.0 percentage points, with the employee on the worse side of it.

The gap gives a benefits team a reason to review employee and family results separately: the combined 69.6% share hides the higher share among employees. The data do not establish why the two groups differ.

One in seven names a B12 supplement — and a supplement is not automatically the fix#

The survey asks separately about supplements and diet.

Neither of these shares measures whether anyone is getting enough B12. The supplement question is a set of ticked options, not a verified record of what someone takes or at what dose. The diet question records a label, not an amount. It lists vegetarian and eggetarian separately, but neither label verifies what foods someone eats. Dairy, eggs where eaten, and fortified foods can supply B12 without meat or fish; the survey does not measure how much of these foods anyone consumes. Nothing in the survey identifies anyone eating no animal-source food at all.

The laboratory and survey results cannot establish whether supplements are reaching people with low B12. The 69.6% comes from reports; these are survey responses; the two datasets are not linked at the individual level. The supplement responses therefore do not show which low B12 results, if any, followed supplement use.

There is also a reason a supplement is not a guaranteed fix, and it has nothing to do with whether someone remembers to take it.

B12 deficiency can look like overwork#

Some of its complaints can resemble the effects of a hard quarter:

Two questions for your screening panel#