Blood Biomarkers as a Nutrition Input

Why a nutrient marker is not a simple verdict

Expert panels in the Biomarkers of Nutrition for Development (BOND) project were set up to guide how nutrient markers are selected, used and interpreted. [1] Their vitamin A review shows the problem: serum retinol is under tight body control, and it falls during infection and inflammation because its carrier protein is a negative acute-phase reactant, which makes status assessment challenging. [1] In other words, a low reading can reflect illness rather than low intake.

A separate expert initiative, INSPIRE, was created partly because inflammation affects how nutrient markers should be selected, used and interpreted. [2] Label: established as a measurement caution.

Reference ranges also differ. MedlinePlus notes that normal ranges can vary from lab to lab, and results outside a lab's range may need further testing. [3] The example is a bilirubin test, but the point applies to blood tests generally: use the range printed on your own report and ask your clinician.

What trials of biomarker-informed advice found

• Food4Me (Europe, 1,269 completers). Internet-delivered personalized advice produced larger and more appropriate dietary changes than conventional advice, but adding blood-marker (phenotype) and genetic information did not enhance effectiveness. [4] The outcome was dietary intake, not disease. Label: promising but limited for personalization in general, insufficient evidence for blood markers adding value.
• PREVENTOMICS (100 adults, 10 weeks). Plans based on metabolic and genetic clusters did not reduce fat mass more than a generic healthy diet; the difference in fat mass change was -0.1 kg (95% CI -1.2 to 0.9). [5] Label: no good evidence of benefit in this trial.
• A US trial of 347 adults (18 weeks) used food responses, microbiomes and health history, and found triglycerides fell more than with standard advice, while LDL cholesterol did not differ significantly. [6] The program mixed several inputs, so the trial cannot say which one mattered. Label: promising but limited.
• A 2024 systematic review in prediabetes or metabolic syndrome (seven trials, 873 people) found consistent gains in HbA1c and waist circumference but inconsistent results for lipids, blood pressure and fasting glucose. [7] Label: mixed.

Biomarker change is not an outcome

A shift in a blood marker does not by itself mean better health. See Biomarker Changes vs Meaningful Health Outcomes and Why Acute Biomarker Changes Are Not Proof of Benefit.

Who should be especially careful

People who are pregnant, have kidney, liver or digestive disease, take medicines, or have a history of eating disorders should discuss any nutrition plan with a clinician or registered dietitian. For test types and limits, see Biomarker Tracking and At-Home Tests.

Ordinary guidance still applies

The NHS says most people should get all the nutrients they need from a varied and balanced diet, though some people may need supplements. [8] See Food-First Nutrition for everyday nutrition.