5.4: U.K. Dietary Reference Values (8a.4)

The United Kingdom was the first country to adopt a frame-work for developing Nutrient Reference Values and these are termed “Dietary Reference Values” (DRVs) in COMA,1991; the frame-work used is depicted in Figure 8a.1. The generic term “Dietary Reference Values” was used to embrace three reference levels: the “Estimated Average Requirement” (EAR = AR), the “Reference Nutrient Intake” (RNI = RI), and the “Lower Reference Nutrient Intake” (LRNI, set at 2SDs below the AR). The term “reference values” was adopted in an effort to prevent users interpreting the figures as recom­mended or desirable intakes. Instead, the expert panel hoped that users would select the figure most appropriate for its intended use (Beaton, 1998).

UK Nutrient Reference Values for certain nutrients are not available for children < 5y of age. NRVs for thiamin and niacin equivalents were recalculated in 2011, based on the revised energy require­ments established using a new approach (Section 8a.4.5) (SACN, 2012).

The NRVs for vitamin D for males and females aged 1–18y were also revised in 2016 (SACN) and now include a recom­men­dation for selected life-stage groups to take a daily vitamin D supplement, especially from October to March.

A recent review of nutritional require­ments of adults aged > 65y in the UK (Dorrington et al., 2020) has concluded there is evidence to support age-specific UK recom­men­dations for those aged > 65y, for the RNIs for protein (1.2g per kg/d), calcium (1,000mg/d), folate (400µg/d), vitamin B₁₂(2.4µg/d) although to date, none of these suggested changes have been made by SACN (2016). In contrast, Dorrington et al. (2020) suggest that the current recom­men­dations for the general pop­ula­tion for sugars, dietary fiber and fatty acids, sodium and alcohol are probably appropriate for older adults.

8a.4.1 U.K. Estimated Average Requirement (EAR = AR) for nutrients

The term “Estimated Average Requirement” (EAR) in COMA,1991 represents the level of the nutrients estimated to meet the nutrient require­ment of 50% of the healthy indi­viduals in a particular sex and life- stage group. The EAR is especially useful for evaluating the possible ade­quacy of nutrient intakes of pop­ula­tion groups.

8a.4.2 U.K. Reference Nutrient Intake (RNI)

Reference Nutrient Intakes (RNIs) were defined as 2SDs above the average require­ment for each nutrient and represent the target for an indi­vidual's nutrient intake. The U.K. RNIs for minerals and vitamins are shown in Appendix 8a.1 and Appendix 8a.2 respectively. When data about variability in require­ments were insufficient to calculate a SD, a coefficient of variation for the EAR of 10% was assumed. Habitual intakes above the RNI₉₈ will be ade­quate for all but 2–3% of indi­viduals in a specific sex and life-stage group. The RNI should not be used in relation to groups (COMA,1991).

8a.4.3 U.K. Safe Upper Levels for Nutrients

Safe upper levels were set by the U.K Expert Group on Vitamins and Minerals (EVM, 2003). They represents an intake that can be consumed daily over a lifetime without significant risk to health. Intakes from all sources were taken into account. The EVM group defined ULs for vitamin B₆, β-carotene, vitamin E, zinc, copper, selenium, boron and silicon, and also provided guidance for those nutrients for which the data­base was inade­quate to establish a UL. Nutrients in this category included biotin, folic acid, niacin, riboflavin, pantothenic acid, thiamin, vitamin B₁₂, vitamin A, vitamin C, vitamin D, vitamin K, chromium, cobalt, iodine, manganese, molybdenum, nickel, tin, calcium, phosphorus, magnesium, iron, iodine, chromium, tin, and potassium. Suggested levels for these nutrients would not be expected to be associated with any adverse effects. Nevertheless, the EVM acknowledged that for those nutrients for which the data­base was inade­quate to establish a UL, the suggested levels may not be applicable to all life stages or for lifelong intake, and should not be used as a UL.

8a.4.4 U.K. Additional Levels

Lower Reference Nutrient Intakes (LRNIs) were set by COMA,1991 at two standard deviations below the AR for each nutrient. The LRNIs represent the lowest intakes that will meet the needs of some indi­viduals in the group. The LRNIs are used as a monitoring tool for the UK National Diet and Nutrition Surveys. Habitual intakes below the LNRI are almost certainly inade­quate for most indi­viduals. For confirmation, however, biological parameters should be measured, especially when the nutrient intake of the indi­vidual lies between the LRNI and the EAR.

Safe Intake values were also set for some nutrients with important functions in humans, but for which the expert committee considered there were insufficient data to set DRVs (e.g., biotin, pantothenic acid, vitamin E, vitamin K, manganese, molybdenum, and chromium). Safe Intake was judged to be a level or range of intake at which there is no risk of deficiency and below a level where there is a risk of undesirable effects (COMA,1991).

8a.4.5. U.K. Average Requirement for Energy

In view of the increasing risk of overweight and obesity in the U.K., the SACN (2012) adopted a prescriptive approach and identified energy require­ment values in relation to the best estimates of healthy body weights. Using this prescriptive approach, an overweight group consuming the amount of energy recom­mended for a healthy weight group are likely to lose weight whereas those under­weight should gain weight (SACN, 2011).

The U.K average require­ments for energy for adults of specified age, sex, and height assuming a median physical activity level (PAL) of 1.63 and expressed as MJ/d or kcal/d are available as tables in (SACN, 2011). Values given in the tables are derived from mean heights in 2009 for England (Health Survey for England 2009). These revised values apply to all adults unless energy expenditure is impaired, when a lower PAL value of 1.49 should be used. For children aged 1-18y, age and sex specific energy require­ments, with PAL values ranging from 1.40 to 1.75, are presented, expressed as MJ/d or kcal/d. Separate tables for infants by age and sex who are breast-fed, fed breast-milk sub­stitutes, mixed-feeding or unknown by age and sex are given, expressed as both MJ/kg or kcal/kg per day and MJ/d or kcal/day. The energy require­ments for infants were adopted from FAO/­WHO/­/UNU (2004).

The new U.K. factorial approach to establish energy require­ments is based on the assumption that total energy expenditure (TEE) (or EAR) is equal to BMR × PAL (SACN, 2011). This approach was developed in recognition of the large unpredictable variation between indi­viduals (inter-indi­vidual variation) in discretionary activity. This large inter-indi­vidual variation in discretionary activities is attributed in part to spontaneous physical activity (SPA). SPA includes body movements associated with activities of daily living, changes in posture, fidgeting, and a propensity for locomotion. An additional issue recognized by SACN (2011), is that PAL values, previously assumed to be independent of body weight, appear to have a complex relationship with body weight (Millward, 2012).

Conventionally, TEE is expressed as a multiple of Basal Metabolic Rate (BMR) and (PAL). Therefore:

\[\mathrm{TEE}=\mathrm{PAL} \times \mathrm{BMR}\nonumber\]

Hence

\[\text { PAL = TEE / BMR }\nonumber\]

In this new approach, the PAL values were derived directly from DLW measurements of TEE in a reference pop­ula­tion instead of applying PAL values predicted from lifestyle information, as used earlier by COMA in 1991 and 1994. Hence, to extract PAL values, TEE values measured by DLW in a suitable adult reference pop­ula­tion were divided by BMR calculated from prediction equations of Henry (2005) and applying healthy body weights equivalent to a BMI of 22.5kg/m² and at the appropriate height of the adult population. from that same reference pop­ula­tion (Tooze et al., 2007; Moshfegh et al., 2008). From the data on the distribution of PAL values in the adult reference pop­ula­tion, PAL values for the 25th, median, and 75th percentiles corresponding to sedentary, low, and moderate activity were identified: i.e., 1.49; 1.63, and 1.78, respectively.

A separate 2006 data set for children was compiled from all DLW measurements of TEE of children aged over one year. The BMR for children was estimated using the equations of Henry (2005), applying healthy body weight based on the 50^th percentile of the UK‑WHO Growth Standards (aged 1–4y) and the 50^th percentile of the UK 1990 reference for children and adolescents aged > 4y. From these data, PAL values for children aged 1–3y, 3 to less than 10y, and 10–18y were identified. To account for the cost of energy deposition during growth of the children (not included in TEE measured by DLW), the PAL values were adjusted by a simple +1% adjustment of PAL (PAL × 1.01). This results in acceptably low levels of error for children aged1–18y. Adjusted median PAL values for the three age groups were 1.40, 1.58, and 1.75. The reader is advised to consult SACN (2012) for more details.

8a.4.6 U.K. Ade­quate Macronutrient Distribution Range (AMDR)

The United Kingdom also proposed recom­men­dations for carbohydrate, sugars, fats, and fatty acids. These are not defined in the same way as those for the micronutrients. They represent average intakes for pop­ula­tions and not for indi­viduals, which are consistent with good health, and are expressed as a percentage of daily total energy intake and as a percentage of food energy (i.e., excluding the contri­bution from alcohol). Table 8a.3

Table 8a.3 UK dietary reference values (DRVs) and the WHO ranges of population nutrient intake goals (2003) for the energy supplying macro­nutrients for the prevention of diet-related chronic diseases.
Figures are for percentage of total energy, unless otherwise stated. The U.S. and Canadian Acceptable Macronutrient Distribution Ranges (AMDRs) intended for indi­vidual adults are shown for comparison.
¹ Recommendations apply to adults and children > 5y, unless otherwise stated.
² Represent the population average intake that is judged to be consistent with the maintenance of health in a population.
^a Total fat includes all saturated and unsaturated fat (mono-and polyunsaturated)
^b Saturated fat – several studies have shown a high saturated fat intake to be linked with high blood cholesterol. Elevated blood cholesterol is a risk factor for coronary heart disease. Studies have shown that replacing saturated fat with unsaturated fat in the diet reduces blood cholesterol and lowers the risk of heart disease and stroke
^c This is calculated as total fat−(saturated fatty acids + unsaturated fatty acids + trans fatty acids)
^d Total carbohydrate includes all starch, sugars and dietary fiber
^e Free sugars are sugars added to foods and drinks by the manufacturer, cook, or consumer, plus sugars naturally present in honey, syrups and fruit juice
^f Total fiber is the combination of Dietary Fiber, the edible, nondigestible carbohydrate and lignin components as they exist naturally in plant foods and Functional Fiber, which refers to isolated, or synthetic fiber that has proven health benefits.
^g Women should not regularly drink more than 2-3 units of alcohol/day; Men – should not regularly drink more than 3-4 units of alcohol/day
^h Target salt intakes set for adults (and children) do not represent ideal or optimum consumption levels, but achievable population goals
* Based on SACN 2015 recom­men­dations for the population ≥ 2y
** Based on COMA 1991 recom­men­dations for the population ≥ 5y
+ Based on WHO Guideline, 2015: Sugars intake for adults and children. Geneva, World Health Organization
++ Based on WHO.Guideline, 2012: Sodium Intake for Adults and Children; World Health Organization: Geneva, Switzerland.
## From USDA U.S. Department of Health and Human Services Dietary Guidelines for Americans (2010) www.dietaryguidelines.gov
### Based on Sodium Intake in Populations: Assessment of Evidence (2013) IOM of the National Academies Press

Dietary component	UK^1^, 2	WHO^2	US/Canadian AMDRs
Total Fat*	Reduce to less than 35% of food energy^a (excluding alcohol)	15–30%	20–35%
Saturated Fat	Reduce to less than 11% of food energy^b(excluding alcohol)	<10%	As low as possible with a nutritionally adequate diet
PUFAs	6.5%	6–10%
n-6 PUFAs (linoleic acid)		5–8%	5–10%
n-3 PUFAs α-linolenic acid		1–2%	0.6–1.2%
Trans fatty acids	< 2%	≤ 1%	As low as possible with a nutritionally adequate diet
MUFAs		By difference^c	UL not set
Total^d carbo- hydrate**	50% of food energy^dwith free sugars less than 5%^e	55–75% with free sugars <10% preferably <5% (25g/d)	45–65% with added sugar < 5–15% total energy^##
Protein	15%	10–15%	10–35%
Cholesterol	No specific recommendations	< 300mg/d	As low as possible with a nutritionally adequate diet
Dietary fiber	Adults 30g/d	Adults 25g/d	^fTotal fiber AI: 19–50y: 25g/d > 51y: 21g/d
Fruit and Vegetables	Increase to ≥ 5 portions (400g) of a variety of fruit and vegetables per day	≥ 400g/d	9–10 servings/d for Canadian adults 5–9 servings/d for U.S. adults
Alcohol	Should not provide more than 5% of energy in diet^g
Salt (Adults)	Not > 6g/d (2.4g Na)	Not > 5g/d (2g Na)	< 2.3g/d; if ≥ 51y then < 1.5mg/d^h###

summarizes the current U.K. recom­men­dations for the macro­nutrients (COMA,1991; 1994; SACN, 2016) and compares them with the WHO (WHO/FAO, 2002) pop­ula­tion nutrient intake goals for the prevention of diet-related chronic diseases (Section 8a.7.6). The U.S. and Canadian Acceptable Macronutrient Distribution Ranges (AMDRs) for adults (IOM, 2002) (Section 8a.5.6) are also given for comparison. Note that these U.S. and Canadian recom­men­dations, unlike those set by the United Kingdom, EFSA, and WHO, are intended for use by indi­viduals, as noted earlier.

In the UK, SACN (2016) included a recom­men­dation for free sugars, stating that the average pop­ula­tion intake of free sugars should not exceed 5% of total dietary energy for persons from 2y of age. They defined free sugars as those sugars added to food or those naturally present in honey, syrups and unsweetened fruit juices, but excluded lactose in milk and milk products. This report also stated that consumption of sugar-sweetened beverages should be minimized in children and adults in view of the evidence that consumption of sugar-sweetened beverages as compared with non-calorically sweetened beverages leads to greater weight gain and increases in BMI. SACN (2016) also adopted a broader definition of dietary fiber than that adopted earlier, and provided for the first time average pop­ula­tion dietary recom­men­dations for fiber intake for children and adolescents ranging from 15g/d(2–5y) to 30g/d (16–18y); see Pyne and Macdonald (2016) for more details.