Please note the Chair of the Scientific Advisory Committee on Nutrition (SACN), Professor Ian Young, welcomes the opportunity to provide oral evidence to the House of Lords Select Committee on Food, Diet and Obesity.

Written evidence summary

This response provides answers to questions 4 and 5 of the House of Lords Committee on Food, Diet and Obesity call for written evidence. It also responds to a number of issues raised during the course of the oral evidence sessions in relation to SACN [1].
SACN provides independent scientific advice on, and risk assessments of, nutrition and related health issues. It advises the 4 UK health departments and other government departments and agencies.
SACN’s remit is to gather and assess scientific information (risk assessment). It does not have a policy making role (risk management). Some of the questions asked in this call for evidence go beyond SACN’s remit, but SACN is aware that the Office for Health Improvement and Disparities (OHID) within the Department of Health and Social Care (DHSC) is preparing a response which will cover the full set of questions.
SACN undertakes a robust, transparent approach to the consideration of evidence in line with the SACN framework [2] for evaluating evidence. Members have a duty to act in the public interest, in accordance with the ‘Code of Practice for Scientific Advisory Committees [3] and SACN’s ‘Code of Practice’[4], and to be independent and professionally impartial. Members are required to declare any potential conflicts of interest which are published on the SACN webpage.
UK dietary reference values (DRVs) and dietary recommendations are based on advice from SACN and its predecessor the Committee on Medical Aspects of Food Policy [5] (COMA).
SACN has published a range of risk assessments [6],[7],[8],[9],[10],[11],[12],[13] relevant to this call for evidence, including a position statement on processed foods and health [14], published in July 2023. This statement summarised a scoping review of the evidence on food processing and health, which concluded that the association between higher consumption of (ultra-) processed foods and adverse health outcomes is concerning, but it is unclear whether these foods are inherently unhealthy due to processing, due to their nutritional content or due to a combination of factors. This statement and SACN’s other publications of relevance are summarized below.

Written evidence response

Introduction to SACN

The Scientific Advisory Committee on Nutrition (SACN)[15] provides independent scientific advice on, and risk assessments of, nutrition and related health issues. It advises the four UK health departments and other government departments and agencies.
Members are appointed as independent scientific experts on the basis of their specific skills and knowledge. The committee also includes 2 lay members and a member with industry expertise.
SACN is a committee of the Office for Health Improvement and Disparities (OHID) within the Department of Health and Social Care (DHSC) and is supported in its work by a secretariat based in OHID. The secretariat has scientific expertise that enables it to work closely with SACN members to draft risk assessments.
SACN members have a duty to act in the public interest according to the SACN code of practice [16].
See Annex 1 for further details of SACN’s remit, work programme, approach to evidence, independence and declarations of interests.

SACN’s role in development of dietary advice

UK dietary reference values (DRVs) and dietary recommendations are based on advice from SACN and its predecessor, the Committee on Medical Aspects of Food Policy [17] (COMA). Many original COMA recommendations have been superseded by subsequent risk assessments undertaken by SACN. For example, SACN has updated dietary recommendations on salt and health [18], dietary reference values for energy [19], carbohydrates and health (including sugars and fibre)[20] and saturated fat [21]. SACN has also provided advice on specific population groups including children aged 0 to 1 years, aged 1 to 5 years and considered the evidence based on older adults.

Question 4: The influence of pre- and post-natal nutrition on the risk of subsequent obesity, and the specific influences on the diet of children and adolescents that contribute to the risk of becoming obese

SACN report on early life nutrition

In November 2011, SACN published its report on the influence of maternal, fetal and child nutrition on the development of chronic disease in later life [22].
SACN concluded that there is cause for concern about the later health consequences of compromised or excessive nutrient supply during early fetal and infant life. It noted that in the context of reproduction, the impact of current dietary patterns on women and girls is of particular concern and considered that improving the nutritional status of women of childbearing age, infants and young children has the potential to improve the health of future generations.
SACN concluded that observational evidence suggests that infants who are not breastfed tend to have slightly higher blood pressure and serum total cholesterol concentrations in adulthood. They may also be at greater risk of type 2 diabetes and are more likely to be obese in later life.
SACN made a number of recommendations including that ‘optimisation of fetal development requires the achievement of adequate nutritional status of the mother prior to conception. Interventions to reduce chronic disease risk in future generations should address dietary and lifestyle change in infancy and adolescence, to ensure adequate nutrition throughout adolescent and reproductive years and in order to improve women’s reproductive health’.

SACN report on feeding children aged 0 to 1 years

In July 2018 SACN published its report Feeding in the first year of life [23]. SACN’s conclusions support existing advice on infant feeding, introduction of solid foods (sometimes called complementary feeding) and diversification of the infant diet.
SACN concluded and recommended the following:

SACN concludes that breastfeeding makes an important contribution to infant and maternal health. SACN recommends retaining existing advice for women to exclusively breastfeed for around the first 6 months of life and to continue breastfeeding for at least the first year of life once solid foods have been introduced.
SACN recommends that advice on the age of introduction of solid foods should remain unchanged. That is, most infants should not start solid foods until around the age of 6 months, having achieved developmental readiness.
SACN recommends that a wide variety of solids foods, including iron-containing foods, should be introduced in an age-appropriate form from around 6 months of age. Once solid foods have been introduced, the types of food, flavours and textures offered should become increasingly diverse. SACN noted that new foods may need to be presented to infants on many occasions before they are accepted, particularly as infants get older.
SACN recommends that advice on the introduction of solid foods should state that allergenic foods (including peanut and hen’s egg) can be introduced from around 6 months of age and need not be differentiated from other solid foods. The deliberate exclusion or delayed introduction of peanut or hen’s egg beyond 6 to 12 months of age may increase the risk of allergy to the same foods.

SACN report on Feeding children aged 1 to 5 years

In July 2023, SACN published its report Feeding young children aged 1 to 5 years [24]. The report highlighted findings from UK dietary surveys indicating that current diets of young children in the UK do not meet dietary recommendations for several nutrients, and that intakes of calories, sugar, protein and salt in young children exceed recommendations. Commercial baby foods are one of the main contributors to energy and sugar intakes in this age group in children who consume these products, with consumption of sweet and savoury snack foods increasing with age.
Systematic review evidence informing this report indicated that in young children aged 1 to 5 years:

higher total protein intake is associated with increased Body Mass Index (BMI) in later childhood
higher sugar-sweetened beverage consumption is associated with increased BMI and risk of overweight and obesity in childhood
higher child BMI or weight status is associated with higher adult BMI or risk of overweight or obesity
higher free sugars intake is associated with increased development of dental caries in childhood and adolescence.

SACN made several recommendations in relation to foods and drinks that may be classified as ultra-processed:

UK dietary recommendations on average intake of free sugars (that free sugars intake should not exceed 5% of total dietary energy intake) should apply from the age of 1 year
children aged 1 to 5 years should not be given sugar-sweetened beverages
dairy products (such as yoghurts and fromage frais) given to children aged 1 to 5 years should ideally be unsweetened
formula milks (including infant formula, follow-on formula, ‘growing-up’ or other toddler milks) are not required by children aged 1 to 5 years
foods (including snacks) that are energy dense and high in saturated fat, salt or free sugars should be limited in children aged 1 to 5 years
commercially manufactured foods and drinks marketed specifically for infants and young children are not needed to meet nutritional requirements

SACN recommended that government consider strategies to reduce consumption of:

free sugars and excess protein in children aged 1 to 5 years
foods (including snacks) that are energy dense and high in saturated fat, salt and free sugars in children aged 1 to 5 years, while encouraging uptake of healthier snacks
sugar-sweetened beverages in children aged 1 to 5 years

Work is underway on a new Infant Feeding Survey (IFS) which will provide valuable information on infant feeding behaviours including breastfeeding and the use of foods and drinks other than breastmilk with findings expected in 2025.

SACN consideration of nutrition and maternal health

SACN is currently carrying out a risk assessment on nutrition and maternal health [25].
The terms of reference are for the working group to:

review the scientific basis of current dietary recommendations for women during preconception, pregnancy and up to 24 months after delivery, in relation to maternal health and pregnancy-related outcomes (that is maternal outcomes during pregnancy, childbirth and up to 24 months after delivery)
make recommendations based on the review of the evidence

SACN is due to publish a draft report on nutrition and maternal weight outcomes for public consultation later in 2024.

Dietary data

SACN is reliant on nationally representative dietary data to undertake its risk assessments.
Pregnant and lactating women will be included in the UK National Diet and Nutrition Survey (NDNS), the primary and nationally representative tool for monitoring dietary intake in the UK, from Year 16 (summer 2024). SACN have previously noted limitations associated with the lack of representative survey data on dietary intakes and status of pregnant women in the UK.[26]
Work is underway on a new Infant Feeding Survey (IFS)[27] which will provide valuable information on infant feeding behaviours including breastfeeding and the use of foods and drinks other than breastmilk with findings expected in 2025. SACN has previously highlighted the importance of the IFS in monitoring UK infant feeding policy and practice [28].

Question 5: The definition of a) ultra-processed food (UPF) and b) foods high in fat, sugar and salt (HFSS) and their usefulness as terminologies for describing and assessing such products.

Ultra-processed foods (UPF) have been a focus of academic, media and parliamentary scrutiny in recent years due to reported associations with a range of adverse health outcomes. UPF, as defined by the NOVA classification, are highly processed, contain additives and tend to be high in calories, saturated fat, salt and sugar.

SACN consideration of processed meat

In its 2010 report on iron and health [29] SACN concluded that red and processed meat intake is probably associated with increased risk of colorectal cancer.
Based on SACN’s report, the UK government advises that high consumers of red and processed meat (i.e. more than 90g per day) reduce their consumption (to no more than the 70g per day)[30].
The NOVA classification does not classify all processed meat as UPF (NOVA group 4). It considers smoked, cured and salted meats as NOVA category 3 ‘Processed’[31].

SACN Position Statement on Processed Foods and Health

In July 2023 SACN published a position statement on processed foods and health [32], summarising a scoping review of the evidence on food processing and health. This included evaluation of the methods of applying the UPF definition in the UK, the suitability of such methods and consideration of the availability and quality of evidence on food processing with health.

Conclusions of position statement

SACN concluded that:

systematic reviews consistently reported that increased consumption of UPF was associated with increased risks of adverse health outcomes (including obesity type 2 diabetes, cardiovascular disease, depression, mortality and a range of maternal and child health outcomes). However, SACN noted there were uncertainties around the quality of the available evidence. This is because the available evidence was almost exclusively observational (and therefore unable to show causation) and confounding factors or covariates might not have been adequately accounted for
consumption of (ultra-) processed foods may be an indicator of other unhealthy dietary patterns and lifestyle behaviours. Diets high in (ultra-) processed foods are often energy dense; high in saturated fat, salt or free sugars; high in processed meat; and/or low in fruit and vegetables and fibre
it is unclear to what extent observed associations between (ultra-) processed foods and adverse health outcomes were explained by established relationships between nutritional factors and health outcomes on which SACN had undertaken robust risk assessments.

Overall SACN concluded that the association between higher consumption of ultra-processed foods and adverse health outcomes is concerning. The limitations in the available evidence on processed foods and health (as outlined above) means it is unclear whether these foods are inherently unhealthy due to processing or because a large majority of processed foods are high in calories, saturated fat, salt and/or sugar.
Given SACN’s concerns, the committee has added the topic of processed foods to its watching brief and will consider it at its next horizon scan meeting in June 2024.

Definition of UPF

SACN highlighted that there is no universally agreed definition of ultra-processed foods. The term defines foods by how much processing they have been through rather than their nutritional composition.
SACN evaluated existing classifications of processed foods. Eight classification systems were identified and considered against a set of initial screening criteria. NOVA was the only processed food classification that met SACN’s initial screening criteria as being potentially suitable for use in the UK. However, assessment of the NOVA approach identified some concerns around practical application in the UK. In particular, the classification of some foods is discordant with nutritional and other food-based classifications. SACN noted that the research literature investigating the health impacts of (ultra-) processed foods is dominated by NOVA, therefore any limitations or biases of the NOVA classification may be replicated throughout the research literature.
SACN identified a number of limitations in applying NOVA to the NDNS dataset [33]. The NDNS does not currently capture all of the detail required for classifying foods according to NOVA. For example, it does not include information on sweeteners or other additives, nor the method of food processing or packaging. There is also a risk that researchers may under or over-estimate UPF consumption as a result of oversimplified interpretation of the NDNS food groupings, leading to potential inter-assessor variability. Estimates of UPF intake in the UK based on NDNS data vary by age group and ranged from 51% in adults aged over 19 years to 68% of energy intake in adolescents aged 12 to 18 years28.

Research recommendations

SACN made a number of research recommendations:

further assessment and development of a (ultra-) processed foods classification system that can reliably be applied to estimate consumption of processed foods in the UK.
further evidence exploring relationships between (ultra-) processed foods and health outcomes including:

good quality randomised controlled trials (RCTs) that may help to identify potential mechanisms and establish whether they are independent of energy density or other dietary factors which have been considered in previous SACN risk assessments
good quality prospective cohort studies that can address concerns relating to confounding and reverse causality for observed associations between (ultra-) processed foods and health outcomes
good quality studies that consider the benefits of consuming products with minimal processing in comparison with existing UK dietary recommendations and/or other dietary patterns for which there is evidence of beneficial health outcomes
assessment of any role of food additives or other processing methods in observed associations between (ultra-) processed foods and health

further assessment and refinement of NDNS methodology to better estimate and monitor processed food consumption, while minimising impact on participant burden.

SACN is aware that OHID is engaging with UK funders of research, including the National Institute for Health and Care Research (NIHR), to identify priority areas to improve the evidence on this topic.
SACN is aware that the new contract for the NDNS rolling programme also provides an opportunity to review the dietary data collection tool to achieve better estimates of exposure to processed foods.

SACN consideration of sweeteners

A specific issue of concern in the UPF debate is the use of non-sugar sweeteners. All foods containing these sweeteners are classified as UPF under the NOVA definition.
Guidance from the World Health Organization (WHO) published in May 2023 [34] suggests ‘non-sugar sweeteners (NSS) not be used as a means of achieving weight control or reducing the risk of noncommunicable diseases.’ The guidance highlights that there continues to be uncertainties in the evidence base on sweeteners and the role they may play in supporting weight management. The assessment reported that ‘evidence from a recent systematic review and meta-analyses of randomized controlled trials (RCTs) and prospective observational studies found that higher NSS consumption by adults led to lower body weight and body mass index (BMI), compared with not consuming NSS or consuming lower amounts of NSS, when assessed in short-term RCTs, but was associated with increased BMI and risk of incident obesity in long-term prospective observational studies.’
SACN is currently reviewing the WHO guideline and associated evidence [35].
Sweetener intakes in the UK are likely to have increased with the introduction of the Soft Drinks Industry Levy (SDIL). SACN have already highlighted a lack of monitoring data on sweetener consumption in the UK.

SACN consideration of plant-based drinks

The majority of plant-based drinks (such as soya, oat and almond drinks) would be classified as ultra-processed by the NOVA classification.
A joint working group of SACN and the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT), is conducting a benefit:risk assessment considering both toxicological and nutritional aspects associated with the consumption of plant-based drinks by the UK population. Based on this benefit:risk assessment, the joint committee will provide advice to the UK health departments. The draft risk assessment is due to be published for consultation in 2024 [36].

Annex 1

SACN’s remit

SACN’s advice covers scientific aspects of nutrition and health with specific reference to:

nutrient intakes and nutritional status of the population
nutrient content of individual foods and advice on individual nutrients and diet as a whole, including the definition of a balanced diet
monitoring and surveillance of the above aspects
nutritional issues which affect wider public health policy issues including conditions where nutritional status is one of a number of risk factors (such as cardiovascular disease, cancer, diabetes, oral health, osteoporosis and obesity)
research requirements for the above.

Consideration of vulnerable groups (such as infants, adolescents and older adults), racially and ethnically diverse groups and health inequality underpins all SACN’s evidence evaluations. Where relevant, and when available evidence allows, SACN also considers beliefs and cultural influences. The function of SACN is to gather and assess scientific information (risk assessment) to assist policy making or analysis (risk management). The task of policy making is the responsibility of government, which will consider practical options for responses to the problem on which scientific advice has been sought, assessing those options and making decisions on them.

Where required, SACN may advise on possible practical solutions (for example, consideration of international evidence on the impact of fortification) but does not develop policy on behalf of government. SACN has a public health focus, therefore the treatment of disease is outside SACN’s remit, unless specifically requested to consider (as it did when considering low carbohydrate diets for type 2 diabetes [37]). Alcohol, other than as a source of energy, is also outside SACN’s remit.

SACN’s work programme

SACN’s current work programme includes:

maternal health – a risk assessment of nutrition and maternal weight outcomes. A second stage of this work will focus on other aspects of maternal nutrition.
plant-based drinks - a joint benefit:risk analysis considering both the nutrition and toxicological aspects associated with consumption of plant-based drinks by all age groups in the UK population
vitamin D fortification - a rapid review of international fortification policies and bioavailability D2/D3, in response to a request in 2022 from the Secretary of State for Health to consider options for improving vitamin D intakes and vitamin D status of the UK population and for reducing disparities.
sweeteners - in May 2023 the World Health Organisation (WHO) published a conditional guideline that suggests ‘non-sugar sweeteners (NSS) not be used as a means of achieving weight control or reducing the risk of noncommunicable diseases.’ SACN agreed to consider the guideline and associated systematic review and considered a draft paper at the November 2023 SACN meeting [38] and is due to consider again at the June 2024 SACN meeting.
SACN framework and methods for evidence evaluation - the framework subgroup provides ongoing methodological support to SACN and its subgroups and working groups, including keeping the SACN framework under review to ensure it continues to be fit for purpose.
Given SACN’s concern in relation to processed foods and health, SACN will be considering evidence published since its position statement, in June 2024 as part of its horizon scan.

SACN currently sets its own work programme. SACN’s framework for the evaluation of evidence [39] allows SACN to weigh up a number of factors in determining how and if a topic is taken forward. Considerations include:

new evidence on possible diet-health relationships, health benefits, health risks, or nutritional status of the UK population
requests from government ministers, UK Health Departments or other government departments
requests from interested parties (such as non-governmental organisations or industry)
issues raised by SACN, its subgroups or working groups (for example, through horizon-scanning)
changes in legislation
emerging issues arising from the UK or international expert bodies, such as the European Food Safety Authority, NICE, or WHO.

SACN undertakes a horizon scan every 2 years. At the last horizon scan meeting held in 2022 [40], SACN agreed to take forward the following pieces of work:

a step wise approach to considering wholegrain, firstly to agree a definition
a rapid review of iodine (to be started once resources allow)
consideration of vitamin D recommendations for dark-skinned population groups (expansion of current vitamin D fortification working group)

At the previous horizon scan the committee agreed to consider iron bioavailability.

The next SACN horizon scan meeting is due to take place on 20 June 2024, when the timing for these pieces of work will be discussed, as well as discussing topics on SACN’s watching brief:

sweeteners
plant-based diets
protein
omega-3 fatty acids
calcium
folic acid
nutrition and COVID-19

SACN approach to evidence

SACN undertakes a robust, transparent approach to the consideration of evidence in line with the SACN framework [41] for evaluating evidence. This includes:

publishing all meeting minutes and some meetings held in open session (see below)
calls for evidence
use of NDNS and Infant Feeding Survey data - including new analysis as needed
use of systematic approaches to consider evidence including systematic searches (with support from the UK Health Security Agency (UKHSA) knowledge and library services), the use of quality assessment tools and the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) framework [42].
consultation on draft reports and responses to all comments are published.

The Deputy Chief Medical Officer (DCMO) is the Senior Responsible Officer (SRO) for SACN has a key governance role. Responsibilities include:

formally appointing the Chair and members to the committees
undertaking a yearly appraisal of the Chair
terminating any contracts, as appropriate
advising secretariat on governance issues, as necessary.

DCMO meets with the SACN Chair quarterly.

SACN is committed to values of openness and transparency as described in the code of practice.

Where possible, the committee’s main meetings are held in open session and external observers have the opportunity to ask questions at the close of the meeting. However, meeting sessions relating to ongoing evidence evaluations and all working group and subgroup meetings are closed to external observers. This is to allow unconstrained discussion of the evidence and formulation of draft conclusions and recommendations before these are shared and finalised.

The agenda and papers for the open sessions of main committee meetings are published on the SACN webpage approximately two weeks before a meeting. Once agreed by members, the detailed minutes of SACN, working group and subgroup meetings are also published on the SACN webpage.

SACN independence and interests

Members of SACN and its working groups are appointed as individuals in their own right to fulfil the role of the Committee, not as representatives of their particular profession, employer or interest group. They have a duty to act in the public interest, in accordance with the ‘Code of Practice for Scientific Advisory Committees [43]’ and to be independent and professionally impartial.

Members of SACN are appointed in line with the government’s public appointments process [44].

In keeping with the ‘Code of Practice for Scientific Advisory Committees’ SACN membership includes lay members and a member with technical industry expertise to ensure a broad range of skills, expertise and experience are available during discussions. No SACN members are directly employed by industry.

Members are required to declare any potential conflicts of interest annually and new ones at the first appropriate committee meeting which is included in the minutes and published on the SACN website [45]. Declarations for research interests highlight industry partners; such partnerships may be a pre-requisite for some types of nutrition research (e.g. to provide specific foods stuffs or data; as a requirement of some research grants including Biotechnology and Biological Sciences Research Council (BBSRC)).

SACN’s conclusions reflect the considerations of the whole of SACN and are not influenced by any individual member of the Committee. Where members have an direct interest this is handled in accordance with the SACN code of practice and is minuted. Members with a direct interest on a specific topic or issue may be excluded from discussion [46].

27 March 2024

[3] Code of Practice for Scientific Advisory Committees and Councils: 2021 - GOV.UK (www.gov.uk)

[9] SACN Salt and Health report: recommendations on salt in diet - GOV.UK (www.gov.uk)

[18] SACN Salt and Health report: recommendations on salt in diet - GOV.UK (www.gov.uk)