Food & Nutrition
Dietary assessment and nutritional status
In a study of a functional material, diet is background that has to be controlled; it can also be the subject of the research itself. The institute works on both.
Diet as background — control
To see the effect of a test material, the influence of diet must be controlled. Without that, an observed change cannot be separated from a change in what participants were eating.
| Method | How it is applied |
|---|---|
| Dietary records | Three- or seven-day records collected before and after the study to establish changes in energy and nutrient intake. |
| Dietary instructions | Participants are asked to maintain their usual diet, with prohibited items (similar functional foods) specified. |
| Run-in period | One to two weeks before the study proper to stabilise the baseline. |
| Covariate adjustment | Energy intake and similar variables are included as covariates at the analysis stage. |
Diet as subject — intervention studies
We also design and conduct studies in which the dietary pattern itself is the intervention. These bring difficulties that material studies do not.
- Blinding is hard — participants know what they are eating, which constrains placebo-controlled design.
- Compliance must be measured — dietary records are combined with biomarkers such as circulating fatty acid composition.
- Attrition is high — sample size calculations must allow generously for withdrawal.
- The intervention must be defined precisely — a broad label such as 'plant-based diet' is not reproducible; the composition must be documented.
Assessing nutritional status
Intake assessment
24-hour recall, food records, food frequency questionnaires. Each has a different error structure, so the choice follows the purpose of the study.
Biochemical assessment
Circulating vitamin and mineral concentrations, fatty acid composition — used to corroborate self-reported data.
Anthropometry
Weight, height, waist circumference, body fat percentage. Procedure and equipment must be fixed for measurements to be comparable across time points.
Questionnaires
Instruments of established validity. Where a translated version is used, the validity of that translation must be confirmed.
The principal investigator's thirty years of research have centred on plant-based nutrition and the physiology of fasting. The practical judgements involved in designing dietary interventions and managing compliance draw on that experience.
KGHCRI is not a medical institution and does not provide diagnosis, treatment or prescription. The content of this site is provided for research information purposes and does not claim that any product prevents or treats disease.