NCDS: dietary data collection
Information about dietary intake was collected at ages 33 (1991), 42 (2000), 44 years (2003) and 62 years (2020).
On the first three occasions, while no established DAT was used, the frequency of consumption of a limited number of specific foods was recorded and these foods varied across sweeps (see the table below).
It is noteworthy that in 1991 the questions for fresh fruit and salad or raw vegetables were season-specific, but in 2000 they were not. Participants were also asked if they followed a special diet.
In the latest data collection in 2020 (age 62 years), dietary intake was collected using an online diet diary [62]. The Oxford WebQ, developed by the Cancer and Epidemiology Unit at the University of Oxford was used [63]. Briefly, participants are asked to report all food and drink consumed prior to the day they completed the diary, along with portion sizes. Participants completed a 24-hour recall on two days which were randomly selected from the seven days following the nurse visit. Nutrient intake was automatically derived from the diary.
In the COVID-19 sweeps (age 62 years), cohort members were asked about fruit and vegetable consumption before and after the COVID-19 outbreak.
Diet-related questions in NCDS
| 1991 | 2000 | 2003 | 2020 | 2020 | 2020 | 2021 | |
|---|---|---|---|---|---|---|---|
| Sweep 5 | Sweep 6 | Biomedical | Sweep 10 | COVID1 | COVID2 | COVID3 | |
| Age 33y | Age 42y | Age 45y | Age 62y | Age 62y | Age 62y | Age 62y | |
| Respondent (CM = cohort member) | CM | CM | CM | CM | CM | CM | CM |
| Questionnaire source* | PAPI | PAPI | SC | Online DD | CAWI | CAWI | CAWI |
| 24-hour recall | ✔ | ||||||
| Frequency of specific foods: ▼ | |||||||
| Fresh fruit in summer | ✔ | ||||||
| Fresh fruit | ✔ | ||||||
| Salads or raw vegetables in winter | ✔ | ||||||
| Salads or raw vegetables | ✔ | ||||||
| Cooked vegetables | ✔ | ||||||
| Eggs | ✔ | ||||||
| Chips | ✔ | ✔ | |||||
| Sweets or chocolates | ✔ | ✔ | |||||
| Biscuits | ✔ | ||||||
| Biscuits and cakes | ✔ | ||||||
| Fried food not counting chips | ✔ | ||||||
| Food fried in vegetable oil such as sunflower oil, not counting chips | ✔ | ||||||
| Food fried in hard fat such as lard or butter, not counting chips | ✔ | ||||||
| Wholemeal bread or rolls | ✔ | ||||||
| Other bread or rolls | ✔ | ||||||
| Red meat like beef, lamb or pork | |||||||
| Poultry like chicken or turkey | ✔ | ||||||
| Fish | ✔ | ||||||
| White fish (e.g. cold, plaice, halibut) | ✔ | ||||||
| Other fish (e.g. salmon, trout, mackerel, sardines, fresh tuna) | ✔ | ||||||
| Canned tuna fish | ✔ | ||||||
| Pulses such as baked beans and lentils | ✔ | ||||||
| Tea | ✔ | ||||||
| Coffee | ✔ | ||||||
| Milk alone or in milky drinks e.g. hot chocolate | ✔ | ||||||
| Milk on cereal | ✔ | ||||||
| Milk-based savoury dishes (e.g. quiche, cheese or white sauce) | ✔ | ||||||
| Milk-based desserts (e.g. custard, ice-cream, rice pudding) | ✔ | ||||||
| Hard cheeses | ✔ | ||||||
| Soft cheeses | ✔ | ||||||
| Margarine on bread or equivalent | ✔ | ||||||
| Butter on bread or equivalents | ✔ | ||||||
| Type of bread usually eaten** | ✔ | ||||||
| Type of milk usually consumed† | ✔ | ||||||
| On a special diet? | ✔ | ||||||
| How often have you taken supplements of combinations of vitamins / single vitamins or minerals / cod liver oil or fish oil / evening primrose type / other ‡ | ✔ | ||||||
| In month prior to COVID outbreak, how many portions of fresh fruit and vegetables consumed per day | ✔ | ✔ | |||||
| Post-COVID outbreak/last 4 weeks, how many portions of fresh fruit and vegetables consumed per day | ✔ | ✔ | ✔ | ||||
| Food security, use of food banks | ✔ | ||||||
Notes.
* Hyperlinks provided to the NCDS sweep user guide or information pages
**Hyperlinks provided to the dataset on CLOSER Discovery, where available. PAPI = Paper Assisted Personal Interview; CAPI = Computer Assisted Personal Interview; CAWI = Computer Assisted Web Interview; SC = self-completion questionnaire; DD = Diet diary
▼ Response options for frequency of consumption:
– Sweep 5 (1991, age 33 years) = more than once a day, once a day, 3-6 days per week, 1-2 days per week, less than one day per week, never.
– Sweep 6 (2000, age 42 years) = more than once a day, once a day, 3-6 days a week, 1-2 days a week, less than one day per week, occasionally, never.
– Biomedical (2003, age 44 years) = more than four times a day, 2-4 times a day, once a day, 3-6 days a week, 1-2 days a week, less than one day per week, occasionally, never.
‡ Supplement response options: once a day or more, 3-6 times a week, twice a week or less, not in the last month
∆ White bread, wholemeal bread, other brown bread, crispbreads, white pitta bread, wholemeal pitta bread, nan/chapattis, other bread, no bread.
† Whole, semi-skimmed, skimmed, soya, goats, sheep, other, and none.