Erratic eating in shiftworking health professionals – a potential health risk?

AL Jaquiery1,2,3, T Postelnik1, V Alderson-Wallace1, C Wall1

1University of Auckland, New Zealand2Rotorua Hospital, Lakes DHB

3Liggins Institute, University of Auckland

Rationale

• Shift workers on rotating shifts have a higher incidence of metabolic disease than the non-shiftworking population.

• Irregular eating patterns, where the frequency and amount of food intake varies unpredictably from day to day, may be associated with an increased risk of metabolic disease.

• If irregular eating contributes to metabolic disease risk in shift workers, this may be a potentially remediable factor.

Epidemiological studies

• ‘Eating meals irregularly: a novel environmental risk factor for the metabolic syndrome’. Sierra-Johnson, J et al 2008 – Population-based cross-sectional study of 3,607 60-year

old people in Sweden. – Eating meals regularly was associated with a lower

incidence of metabolic syndrome, insulin resistance and (high) serum concentrations of γ-glutamyl transferase.

– ‘... eating meals irregularly may be part of several potential environmental risk factors that are associated with the metabolic syndrome and may have future implications in giving dietary advice to prevent and/or treat the syndrome’.

Experimental studies

• Crossover studies, adult volunteers. Farshchi et al 2004-5

• Period of regular eating followed by 2 weeks of irregular eating of similar food.

• In lean women, an irregular eating pattern resulted in insulin resistance and increased total and LDL cholesterol.

• In obese women, lipid profiles improved on regular eating.

Intravenous Glucose tolerance test (IVGTT)

0 20 40 60 80 100 120 140 160 1800

10

20

glucosebolus

plasma glucosemmol.l-1

time (min)

plasma insulinng.ml-1

0.5g.kg-1

0 20 40 60 80 100 120 140 160 1800.0

0.5

1.0

1.5

time (min)

IVGTT in lambs after 6 weeks of an unpredictable food supply

C n=24

C n=24

U n=20

Post intervention insulin response to IVGTT

Studies in health professionals

• Nurses (acute care hospital, Hong Kong) who worked more than 4 shiftworking episodes/month had higher rates of emotional eating (food intake in response to fear, anger, anxiety) and restraint eating (overeating after abandoning a resolve to diet). Wong et al 2010

• In Japanese medical students the lifestyle factors significantly associated with fatigue were breakfast skipping and meal irregularity. Tanaka et al 2008

Hypothesis

• Nurses and junior doctors on shift work have variable meal and snack frequency across different shifts.

• Mismatch of hunger signals and food intake will disrupt normal

circadian rhythms and appetite regulating pathways.• This will in turn affect metabolism in ways that promote weight

gain and increase the risk of metabolic syndrome.

Observational study investigating eating patterns in health care shift workers (nurses and junior doctors) at Rotorua Hospital, NZ.

Methods• Pilot study, summer studentship.• Approved by Northern Y Regional Ethics Committee.• Volunteer participants recruited from nursing and junior

medical staff.• Height, weight, BMI • Brief questionnaire and 2 week food diary

– Meal and snack frequency was assessed as being variable if values differed by more than 1 SD between shifts

– ‘Foodworks 2009’ – analysis of total energy intake per day on different shifts; and fat, sugar and Na components. (Exercise assumed to be moderate)

– All participants received a feedback sheet with their own data

Resultsnurses Junior doctors

Female n=16 Male n=6 Female n=7

Age years 43.6 (9.3) 26.5 (3.0) 25.0 (1.7)

Time in shift work 17.7 (11.2) years 16.5 (20.6) mth 14.8 (14) mth

BMI kg/m2 30.2 (6.1) 23.6 (6.3) 22.3 (1.6)

Under <18.5 0 2

Healthy 18.6-24.9 4 2 6

Over 25-29.9 5 1

Obese >30 7 2

BMI and age

BMI (kg/m2)

15

20

25

30

35

40

45

20 25 30 35 40 45 50 55 60

Age (years)

JD nurses

R2=0.15, p=0.2 R2=0.03, p=0.5

Variability of food intake

• 50% of nurses had variable meal frequency.

• Female junior doctors had the most variable meal (4/7, 57%) and snack (5/7, 71%) frequency.

• In particular, they ate fewer meals and more snacks on night shift.

Dietary composition

• Nurses (all female) and female junior doctors had double RDI of sugar as % total intake on every shift and on their days off.

• Male junior doctors had mean Na intake 150% RDI.

Summary

• Nurses on shift work had > average BMI, not related to age.

• Irregular eating patterns are common in health care workers doing shift work.

• Women had greater sugar intake, and men greater Na intake, than recommended.

Conclusions

• Health care professionals, like other shift workers, may be at greater risk than the non-shiftworking population for metabolic disease.

• Irregular eating may be a remediable contributor to metabolic disease risk.

• Health administrators have a responsibility to consider ways to minimise these risks for their staff.

• Better definition of the effects of irregular eating on appetite control and metabolism is needed to underpin intervention studies and education.

Acknowledgements

• University of Auckland summer studentship scheme.

• Lakes DHB Ethics Committee• Participants