How does unprocessed, minimally-processed, and ultra-processed food impact dietary quality?

In a recent study published in the Journal of the Academy of Nutrition and Dietetics, researchers assessed the impact of consuming unprocessed, minimally processed (UMP), and ultra-processed foods (UPFs) on diet quality.

Study: Intakes of unprocessed and minimally processed and ultra-processed food are associated with diet-quality in female and male health professionals in the United States: a prospective analysis.Image Credit:Parilov/Shutterstock.com

Background

A poor diet is a significant modifiable risk factor for noncommunicable illnesses. Various metrics have been developed to estimate dietary quality while awarding scores for higher consumption of orders and foods related to a lower chance of chronic diseases, such as fruits, vegetables, whole grains, nuts, legumes, fish, and unsaturated fats.

Reduced points are awarded for higher consumption of foods correlated to a higher risk, such as red and processed meat, sweetened drinks, sodium, sugar, and saturated fats. Generally, higher ratings indicate a healthier diet.

It is uncertain, however, if UMP and UPF consumption is linked with dietary quality measures and whether their consumption and dietary quality have altered in tandem through time.

About the study

In the present study, researchers determined whether the consumption of UMP and UPF are connected to dietary quality indicators in male and female health professionals over a 30-year follow-up period.

The study involved a prospective evaluation conducted as part of the Nurses' Health Study (NHS), which enrolled female registered nurses, and the Health Professionals Follow-up Study (HPFS), which enrolled male health professionals. These two studies involved participants from all US regions who answered a questionnaire every two years on medical history and health behavior and every four years on nutrition and lifestyle.

All participants' dietary intake was evaluated using a validated semi-quantitative food frequency questionnaire (SQFFQ) involving varying foods per cycle. In each follow-up cycle, the total number of food items ranged from 137 between 1986 and 1990, 140 in 1994, 148 between 1998 and 2006, and 152 in 2010.

The SQFFQ was designed to evaluate dietary intake over the last year and featured nine frequency options that ranged between "never or less than one time per month" and "six or more times a day." In both studies, food intake was evaluated per four years, of which the first cycle occurred in 1986 for the NHS and in 2006 for the HPFS.

The food items were categorized into food processing groups. The final list of foods from the SQFFQ of the HPFS and NHS consisted of 205 food items divided into four categories: UMP, processed foods (PF), processed culinary ingredients (PCI), and UPF.

Results

The study comprised 83,263 men and women, including 51,956 recruited from the NHS from 1986 to 2010 and 31,307 enrolled from the HPFS from 1986 to 2006. The mean baseline age in the NHS and HPFS was 49 and 52, respectively.

In 2010/2006, participants in both groups were more physically active than at baseline. The alternate healthy eating index-2010 (AHEI-2010) score was almost 4.9 points more in the NHS in 2010 and 4.6 points higher in the HPFS in 2006 than the baseline. In the 2006 HPFS, the diet portion of UMP was 5% lower, while UPF was 2.9% higher than at baseline.

The multivariable analysis of HPFS and NHS data showed that the average diet-quality score for the lowest to highest UMP score quintiles rose to 56.9 from 53.6 for AHEI 2010 and to 4.6 from 4.3 for the alternative Mediterranean diet index (aMED) and to 25.1 from 24.2 for the dietary approaches to stop hypertension (DASH)-diet score.

Furthermore, in the NHS, the fifth quintile associated with energy percent derived from UMP resulted in AHEI-2010, DASH, and alternative Mediterranean diet index (aMED)-diet scores higher by 3.8, 1.8, and 0.5 points, respectively, compared to the first quintile. In the HPFS, the fifth quintile associated with energy percent derived from UMP led to AHEI-2010, DASH, and aMED diet scores, which were higher than the first quintile.

The average score for diet quality for NHS and HPFS in the first quintile of energy percent derived from UPF for AHEI-2010 was 49.43 and 50.42; aMED was 3.74 and 3.89; and DASH was 22.40 and 22.27 points, respectively. In the NHS, the fifth quintile scores were -4.60 points on the AHEI-2010, -0.55 for the aMED, and -1.81 for the DASH diet. In the HPFS, the highest quintile scored -6.89 points on the AHEI-2010, -0.74 on the aMED, and -2.84 points on the DASH diet than the lowest quintile.

Conclusion

The study findings showed that the two prospective participant groups displayed that UMP had a direct while UPF had an indirect correlation with the aMED, AHEI-2010, and DASH diet scores.

Thus, the consumption of UMP is associated with better dietary quality, whereas the consumption of UPF is associated with poorer dietary quality.

Such relationships were inconsistent over time, which may be partially attributable to the intake of PCI and PF food-processing categories or variations in the SQFFQ.

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.