Health inequality: Framing the debate

Closing Date: 05/10/2022

Optometrists Dispensing Opticians Clinical Practice Professionalism

As part of a series previously published in Optician, I reviewed the literature to describe the ever-growing evidence for the strong link between physical health and systemic well-being and eye health and vision.1 It seems only sensible, therefore, for eye care professionals (ECPs) to be aware of any significant adverse influences upon systemic health, and so be better able to assess ocular health in context and be better able to develop an effective management plan.

In this article, I aim to review the latest evidence for the impact of socioeconomic status upon systemic, and therefore indirectly, ocular health. Health inequalities are the unfair and preventable differences in health between groups within society.2, 3 As ECPs, we should have an awareness of the health and wellbeing of our patients as opposed to passing the issues of deprivation and its impact on health over to the appropriate public health and governmental departments.4


Overall, health relies on a variety of factors. Some of these are non-modifiable, including age, ethnicity or family history. Most factors, however, are modifiable and termed determinants of health. These include health behaviours, access to healthcare, quality of clinical care, socioeconomic factors and the physical environment.4  

According to Sir Michael Marmot, health can be viewed as a broad reflection of society, ‘if health has stopped improving it is a sign that society has stopped improving’.5 The neediest in society are less likely to have access to and receive appropriate care, whereas the less needy in society are more likely to have access to appropriate care.6 Life expectancy has been increasing for over 30 years, has plateaued since 2010 and is declining among women in the most deprived areas.4, 7 Men living in the most deprived 10% areas live nine fewer years than their counterparts in the top 10% areas, and women live seven years fewer.2  

Deprivation causes people to die prematurely.4, 8 The term ‘social gradient’ describes the relationship between health and level of deprivation.9 In the most deprived areas of England and Wales, the mortality rates for individuals aged 15-64 years are 2.8 times higher than those in the least deprived areas for male individuals and 2.1 times higher for female individuals.9, 10 This social gradient has continued during the Covid-19 pandemic.7 Unsurprisingly, these deprived populations are often identified as food insecure,7 with hunger a real-life concern. Over 400 000 children having to skip meals in the first six months of the pandemic.4 Of additional concern is skipping of meals increased during the period when schools were closed.11


Estimates of the extent of poverty in the UK vary considerably, with some sources suggesting the level to be as high as greater than one in five (22%) of the UK population living in poverty.12 This raises the question as to how we define poverty.

The two most commonly used definitions are based on income:

Absolute Poverty; this is a measure of whether the income of the poorest households are keeping pace with inflation. Those households with less than 60% of the median net income from the years 2010 to 2011, uprated by inflation, are considered to be in absolute poverty.13, 14 It has been suggested that absolute poverty does reduce over time,15 provided those on lower incomes see their income rise more than inflation, regardless of whether their income in real terms is falling behind with those on average incomes.14

Relative Poverty; this is a measure of whether those on lower incomes are closing the gap on those on higher incomes, as well as whether they are benefitting from a growing economy.14 This is the preferred metric used by poverty analysts.

A wider appreciation of household living standards can be obtained by incorporating material deprivation, the ability to afford certain necessitates and activities from a predetermined basket of goods.16

Recent forecasts suggest that given the current economic climate, a further 1.3 million people will fall into absolute poverty over the next year (2022-23), accounting for 500,000 children, with additional millions experiencing falling incomes after adjusting for inflation.17

Childhood poverty in England is among the worst in the Organisation for Economic Co-operation and Development (OECD) countries, with over 30% of children in England, or put another way over four million children, living in relative poverty in 2018 and set to increase in the future.5

And the relevance for ECPs? Consider, for example, how it has been stated that those living in areas of greater poverty are more likely to be impacted by age-related macular degeneration (AMD) than those living in more affluent areas.18, 19

Figure 1: Prevalence of obesity by deprivation decile26

Poverty and Obesity

There is an increasing body of evidence showing how obesity is associated with social inequality.20 This association appears to follow an income gradient,21 with children and adolescents in those families on the lowest income being twice as likely to suffer with obesity as those children from the wealthiest families (figure 1).22, 23 This has long-term effects on life expectancy, quality of life and the burden placed on healthcare costs.24

Public Health England has also published data showing that obesity is also more likely among the elderly, some black and minority ethnic groups and those with disability (figure 2).

Figure 2: The variability in impact of obesity

The Marmot report advocates a ‘whole system’ approach to obesity.5 There has been a steady decline in local authority funding for young people’s services since 2010. The funding cuts appear to disadvantage the most deprived areas experiencing the great cuts in spending, coupled with an apparent North-South bias, where the North East is most affected and, the South East the least.5

A variety of measures have been proposed to increase employment and thereby enable families to meet their household needs. Data indicates that 1.6 million children in two parent households, currently live in poverty (figure 3),5 and likely to increase given the rise in unemployment in a post-Covid economy, suggesting that work is no longer a guarantee of adequate subsistence.20

Families living in deprivation spend proportionally more of their disposable income to eat healthily than those not living in deprivation, based on some studies, to the tune of 40% for poorest fifth of UK households compared to 7% for the richest fifth.23

According to Dr Tammy Boyce, co-author of the Marmot report:  

‘With a rising cost of living, the cut to Universal Credit, and the rapidly increasing costs of heating, telling families to eat more fruit and vegetables will simply not work and will, in the end, exacerbate inequalities.’23

Figure 3: Obesity in children

One factor we must focus on is poverty. Every year we see the gap between the most and least deprived children widen. Obesity is increasingly a disease of poverty in the UK, and any attempts to address the problem need to be focused on deprived groups and the causes for their increased vulnerability. Dr Max Davie, officer for health improvement at the Royal College of Paediatrics and Child Health, stated recently: ‘It is extremely important to factor health inequalities into all service design and delivery.’23

The health costs to the NHS due to obesity-related ill health were are over £6bn in 2015 and are set to rise to £9.7bn by 2050 (figure 4).2, 23 The economic costs in the same period were £27bn and are expected to rise to almost £50bn by 2050, and obesity is set to overtake smoking as the biggest cause of preventable death.2

Regional disparity

It seems that some geographic areas are more obesogenic than others. This can be related to a variety of apparently innocuous associations, the most obvious being a disproportionately high level of fast-food outlets in poorer areas.26 Furthermore, physical activity and exercise play an important role in the development of obesity. There is a greater lack of playgrounds and parks in deprived areas, leading to a more sedentary lifestyle and promoting obesity.2, 26

The food that is eaten, often ultra-processed food (UPF), can be categorised as energy-dense yet nutritionally poor. UPFs are high in sugar, fat and salt, and often form a significant part of the food option chosen by those on limited family budgets.21 External factors have also pushed the consumption of such food, with recent studies overwhelmingly demonstrating greater consumption of UPF during lockdown.27 UPF is cheaper than healthier food. For example, in 2012, the healthy food items providing 1,000 calories cost approximately £7.50, whereas the same calories could be obtained through choosing UPF items for £2.50.28

Figure 4: Cost implications of obesity in England2

The consumption of healthy food is found to be related to income. It may well be, therefore, that subsidies to healthy foods could allow access to the worse-off.29 A reduction in the cost of healthy food items results in an increase in fruit and vegetable consumption. Such an approach has been taken further in the most deprived areas of Washington DC, with success through implementing 100% subsidy on fresh produce to tackle obesity.20 This approach to addressing the health problems from obesity has been advocated by some authorities as worthy of introduction in the UK.30

Definitions of obesity

There are a number of definitions used for obesity, and these are used variously in the literature. The one most widely used, and likely to be familiar to readers, is that based upon body mass index (BMI). BMI is calculated using a person’s height and weight. The formula is BMI = weight in kg/(height in metres).2

For most adults, a BMI of 18.5 to 24.9 represents a healthy weight, while 25 to 29.9 suggests being overweight while 30 to 39.9 means defines obesity. Forty or higher is severe or morbid obesity.

BMI is rarely used to diagnose obesity in the clinical setting because people who are very muscular can have a high BMI without much fat. But for most people, BMI is a useful indication of whether they are a healthy weight.

A better measure of excess fat is waist size, which can be used as an additional measure in people who are overweight (with a BMI of 25 to 29.9) or moderately obese (with a BMI of 30 to 34.9). Generally, men with a waist size of 94cm or more and women with a waist size of 80cm or more are more likely to develop obesity-related health problems.

Weight management strategies use diet as their foundation. Indeed, it has been estimated that improvement in diet would prevent 20% of all deaths.31 There is a general acceptance that healthy diets, such as the Mediterranean diet, are found to be rich in whole plant-based food, including fruit, vegetables, pulses, nuts whole grains and oily fish, while limiting saturated fat, added sugar and sodium. A typical Western diet, in contrast, is typified as including refined grains, red and processed meat, added sugar and the consumption of sugar sweetened beverages32 and is generally associated with an increased risk of disease.33  

Ultra-Processed Food (UPF)

Understanding how diet impacts upon physiology and health has traditionally been based on analysis of nutrient content,34 although it is becoming apparent that other aspects of diet are important.32 Classification based on the level of food processing is gaining popularity, as the trend in the last few decades away from minimally processed food and towards greater ultra-processed ready-to-eat meals and snacks gathers pace in many Western

The emergence of UPF began in the UK, USA, Canada and Australia in the 1950s, spreading globally from the 1970s,36 and appears to go hand-in-hand with increased prevalence in obesity32, 35, 37 and non-communicable diseases (NCDs), such as cardiovascular diseases, hypertension, and type II diabetes.38 The term now used for the combination of diabetes, hypertension and obesity is metabolic syndrome. A number of potential mechanisms have been proposed that explain the impact ultra-processed food has on disease processes,39, 40 as shown in figure 5.

Figure 5: Dietary and metabolic mechanisms that may explain the prospective association identified in the literature between consumption of ultra-processed foods and numerous diseases and all-cause mortality40

The Nova classification, developed by researchers at the University of Sao Paulo in Brazil, is the most used processed food classification,32 although other classification systems are also sometimes cited, such as Poti, IFIC, Siga and IARC-EPIC.41 The Nova system looks at the nature, extent, and purpose of the processing rather than the nutrient content or the act of processing.34, 42 43 Food is grouped into four categories depending upon the degree of processing/ intervention that has taken place (figure 6).

The Nova system groups food into the following categories:

  • Minimally Processed Foods (MPF)
  • Processed Culinary Ingredients (PCI)
  • Processed Foods (PF)
  • Ultra-Processed Foods (UPF)

Figure 6: The Nova food classification27, 44

Ultra-processed food is manufactured through a variety of industrial processes contains five or more ingredients (including additives, flavourings and colourings) that no longer resemble the original constituents42 and can be considered cheap sources of energy consisting of little in the way of whole food. Ultra-processed food accounts for over 50% of the total energy intake in many countries,45 with the UK ranking third in consumption of ultra-processed food.46 

Food industry labelling is not standardised, making it a challenge to identify UPFs. A rule of thumb in identification of substances that make food more appealing would include hydrolysed proteins, high-fructose corn syrup and inter-esterified oils, the latter used as an alternative to trans-fats usage and are found in spreads and baked goods.47, 48

It is important to note that many classification systems imply a correlation between ‘processing’ and nutrition.41 It is possible to misclassify some nutrient rich food as ultra-processed, as in the case of fortified ready to eat cereals.49 There is a likelihood that food processing may be considered undesirable and lead to insufficient food safety controls (for example, consuming raw milk).41 Although an exact process has yet to be defined, a number of mechanisms explaining how ultra-processed food promotes obesity have been proposed.30, 46  

Ultra-processed foods do have some desirable features. They are inexpensive to produce, have a longer shelf life, provide nutrients and offer the convenience of being available in ready to eat, or ready to heat options.50 On the flip side, it appears that diets high in UPF promote greater intake of calories and weight gain compared to unprocessed diets (figure 7).50 UPF are consumed as snacks and the consumption of snacks globally accounts for 25% of all calories consumed.51-53 This figure continues to rise, raising the suggestion that some food companies are actively promoting snacking54 and some researchers have acknowledged the addictive nature of UPF.55

It has also been proposed that nutrient content is not the critical link of UPFs with obesity and its sequelae. Rather, the nature and extent of the processing seems important and, coupled with overall dietary patterns,56 impacts the level of ultra-processed food consumed. A recent study into British adolescents noted that eating in a family setting, with the appropriate parental modelling of eating behaviours, is more likely to result in the consumption of less unhealthy food. Whereas eating with their own friends circle, outside of the house or ‘watching TV alone in the bedroom’ had a greater push on ultra processed food intake.57

Figure 7: Weight and calorie intake of stable adults receiving either ultra-processed or unprocessed diets and allowed to eat as much as they wanted. Those on a purely UPF diet ate more calories and gained weight in contrast to those on an ‘eat as much as you want’ unprocessed diet who actually lost weight.50

The Nova system is not without its critics.41, 58 However, a number of countries, including Brazil, have used the Nova classification to inform their health policy and recommend avoidance of UPF,34, 59 There is much debate over the virtues of this approach.40, 60 Overall, the reduction of UPFs in favour of either reformulating or use of less processed foods appears desirable.34, 50

Metabolic Syndrome

Metabolic syndrome (MetS), also known as syndrome X, refers to a variety of risk factors that include any three of the following criteria:61, 62

  • Elevated waist circumference
  • Elevated fasting plasma glucose
  • Elevated blood pressure
  • Elevated triglycerides
  • Reduced high density lipoprotein (HDL)

In addition to ocular findings (which will be addressed in a future article), MetS doubles the risk of CVD and increases the risk of type II diabetes fivefold.53, 63 The prevalence in the UK is estimated to be 33% in adults over the age of 50, according to NHS data from 2019, and is a significant public health concern.64

The increase in prevalence of MetS appears to mirror the increase in obesity and other risk factors, including poor diet, in the past few decades.61 It has been proposed that fat accumulation, particularly visceral fat, sets off a ‘domino effect’ by promoting insulin resistance, a determining factor in the development of MetS.24 The increased insulin resistance impacts dysglycaemia and hyper-insulinaemia, which also favours hypertension and dyslipidaemia.63  

Prevention is currently based around lifestyle changes, including discussions based around normalising body weight and ensuring cardio-metabolic control, such as monitoring lipid levels, blood glucose and blood pressure.65 Associations exist between the proportion of UPFs consumed with a higher prevalence towards MetS,61, 66 particularly among young adults between 20 and 39 years of age.61

These discussions could be incorporated into a comprehensive eye examination. It has been found that a large proportion of adults in their 20s or 30s rely on the optometrist as their primary health care provider.67 It could be argued that diet and exercise habits are formed during these years, and that the clinician has a duty to educate and counsel patients in this age range, to reduce the likelihood of risk factors for metabolic syndrome occurring.64, 67 

The gut microbiome (see Optician 25.09.20) can be modified by the composition of what we eat on a day-to-day basis and has the potential to influence the various risk factors implicated in MetS.68 The use of probiotics may offer additional benefits to the current management of MetS.70

When considering diet patterns, rather than just individual nutrient components associated with MetS, unsurprisingly the Western diet tends to be poor in minimally-processed foods. Conversely, a Mediterranean diet, based on minimally processed foods appears protective.65 In addition to diet patterns, a number of dietary components, including olive oil, capsaicin, curcumin, cinnamon and rosemary, have shown benefit in reducing the likelihood of MetS.64 Poverty is associated with a higher proportion of UPF consumption, and around 50% of children from a lower socioeconomic status background go on to develop metabolic syndrome in adult life. This is irrespective of any subsequent upward social mobility.69


In conclusion, the increase in poverty levels in the UK brings a variety of socioeconomic and healthcare challenges, not least the impact of metabolic syndrome, which has far reaching consequences in clinical practice and will be discussed in the next article.
Table 1 lists some key take home points from this discussion. 

Take home points:

  • Poverty impacts health and its sequalae can impact optometrists in clinical practice
  • Social gradient refers to health and level of deprivation
  • Most deprived areas have adult mortality rates 2-3x higher than least deprived areas
  • Recent forecasts suggest 1.3 million people falling into absolute poverty this year, of which 0.5 million will be children
  • Millions more will see incomes falling after adjusting for inflation
  • Obesity is associated with social inequalities
  • Obesity has impact on life expectancy, quality of life and a burden on healthcare costs
  • Obesity forms a significant risk factor for metabolic syndrome
  • Metabolic syndrome doubles the risk of heart attack and stroke
  • Metabolic syndrome increases risk for Diabetes II five-fold
  • 33% of adults in the UK have metabolic syndrome
  • Poverty is associated with greater UPF consumption
  • Ultra-processed food linked to obesity
  • 50% of children from a lower socioeconomic status background develop metabolic syndrome in adult life  irrespective of any subsequent upward social mobility
  • Importance of understanding how diet impacts our physiology
  • Greater prevalence of ultra-processed food in our diets
  • Dietary patterns mimicking a Mediterranean diet are beneficial
  • The optometrist has a role to play in discussing potential lifestyle changes

  • Dr Rohit Narayan is a senior lecturer at Anglia Ruskin University, Cambridge and a therapeutic optometrist with an interest in holistic optometric care.
  • A follow-up article on the impact of MetS and the role of optometry: be prepared to deal with these px and also begin discussing with px lifestyle changes they can make.


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