Do You Really Eat Your Vegetables? Predicting Patients' Produce Intake

When reporting weight, diet, and exercise, patients may feel pressured to say what they think clinicians want to hear.

As a result, patients often indicate they weigh less, eat less, or exercise more than they actually do. However, clinicians currently have no way of knowing whether the same holds true for fruit and vegetable consumption, a dietary intervention associated with better vitamin and mineral absorption, lower body weight, and improved health.

A multinational team of researchers published a study indicating it is possible to determine whether groups of patients are accurate historians regarding their fruit and vegetable intake. Published in the British Journal of Nutrition, this study shows a correlation between produce consumption and blood biomarkers.

These researchers looked at specific biomarker changes related to fruit and vegetable intake with a goal of elucidating possible dose—response curves. They examined carotenoid (a-carotene, b-carotene, b-cryptoxanthin, lycopene, lutein, and zeaxanthin), folate, and vitamin C concentrations. Since sex, age, body mass index, and smoking all affect serum carotenoids, serum vitamin C, and plasma folate levels, the researchers controlled for these characteristics.

The investigators were able to develop a predictive model of produce consumption that was adjusted for certain subject characteristics. Then, they applied the model to data from 12 diet-controlled intervention studies.

The combined studies created a data pool for 526 men and women. Carotenoid, folate, and vitamin C concentrations positively correlated with fruit and vegetable intake, which the researchers said could be used to validate a patient’s produce consumption. When they used patient-reported intake of fruits and vegetables from well-controlled studies, their model accurately predicted biomarker levels, and it was also able to accurately rank individuals within the group by produce consumption.

While this model can approximate average fruit and vegetable intake within a group, it is not refined enough to estimate individual fruit and vegetable intake. For the time being, pharmacists will just have to trust patients when they say they eat plenty of fruits and vegetables.