21 minute read
Carbs and calories
LOW-CARB AND CALORIE DIETS AND THEIR ROLE IN TYPE 2 DIABETES
Substantial weight loss can induce remission of Type 2 diabetes by improving glycaemic control, enabling patients to reduce or potentially omit their insulin or diabetic oral medication.1 This article examines the role of very low-calorie/carbohydrate diets in maintaining weight loss to benefit glycaemic control.
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Very low-calorie diets (VLCDs), which tend to last for 12 weeks, have been proposed to be a promising intervention to achieve significant weight loss in a short amount of time. VLCDs are defined as clinically supervised diet plans that consist of <800 calories per day and aim to induce weight loss and/or remission of Type 2 diabetes.2 They have consistently been shown to lead to statistically significantly greater weight loss than behavioural weight management programmes based on usual foods.3 Weight loss programmes provided in community groups by commercial organisations have been shown to be more effective than routine management delivered by primary care clinicians, and their efficacy continues to be a prime topic of research in diabetes and weight management.4,5
RESEARCH INTO VLCDS
DiRECT
The Diabetes UK-funded Diabetes Remission Clinical Trial (DiRECT) aims to gain understanding of why weight loss can induce remission.6 The study is ongoing and only recruits participants via NHS General Practices. They are currently collecting data on participants in their fourth and fifth years of support and follow-up. So far, the authors have found that a VLCD successfully induced Type 2 diabetes remission in 46% of participants.6 An average weight loss of 10kg was achieved at 12 months, and the more weight participants lost, the more likely they were to induce remission. Those in the intervention arm who lost >15kg, had remissions for 86% at one year and 82% at two years.6 These participants mostly had an HbA1c in the range of ‘prediabetes’ (42-48mmol/l). So far, the study has proven to be more cost effective and cost saving when compared with standard care.7
DROPLET
Results from the DiRECT study are supported by the Doctor Referral of Overweight People to Low Energy Total Diet Replacement (TDR) Treatment (DROPLET) randomised controlled trial (RCT).8 One hundred and thirtyeight participants were assigned to the TDR programme, which was a 12-week 810kcal/day diet with behavioural support. One hundred and forty participants were assigned to usual care, consisting of behavioural support for weight loss from a practice nurse and a modest calorie deficit, which was not specified. Those in the TDR group lost approximately 7.2kg more than the usual care group, with 45% of them achieving >10% weight loss, compared with only 15% of participants achieving this in the usual care group (see Figure 1). There were also greater improvements in the risk of cardiometabolic disease in the VLCD group.8
MIDAS
With recent national and regional lockdown restrictions, more remote ways of supporting patients are being researched. The Manchester Diabetes
Harriet Drennan RD
Harriet is a Specialist Diabetes and Acute Medicine Dietitian at the University Hospital of North Midlands.
hdrennanrd
REFERENCES Please visit: nhdmag.com/ references.html
Intermittent and Daily Diet Diabetes App Study (MIDAS) is researching the feasibility of a daily VLCD when compared with an intermittent VLCD.9 The intermittent VLCD involves two 800kcal days/week spread over 27 weeks. Participants eat at-maintenance calories for the remainder of the week.9 Both interventions use a liquid meal replacement called Optifast. Individualised, tailored advice is offered throughout from a diabetes specialist dietitian via an app, as well as face-to-face appointments. Contact via the app is offered weekly initially, but is reduced to fortnightly and then monthly over 12 months, as participants settle into selfmanaging their diet. Participants also have monthly contact with a diabetes specialist nurse.9 It will be interesting to note the level of uptake and retention in studies offering support via an app compared with those that don’t. Receiving frequent real-time feedback in an app may help patients feel more accountable and could motivate them to better achieve their weight loss endeavours when compared with traditional consultation follow-ups.
NHS ENGLAND’S LOW-CALORIE DIET PROGRAMME Remission programmes are a key part of Diabetes UK’s work and they have collaborated with Public Health England and the NHS to create NHS England’s Low-Calorie Diet Programme (LCDP).10 This is a 12-week, 900 calorie diet
Very low carbohydrate Low carbohydrate Moderate carbohydrate High carbohydrate Carbohydrate (g/day)
20-50g <130g 130-225g >225g
*based on 2000kcal diet
Carbohydrate: % energy*
6-10%
<26%
26-45%
>45%
intervention, consisting of meal replacement products, based on the success of the DiRECT and DROPLET studies.
The NHS LCDP will initially only be offered to 5000 patients across selected areas of England. Those able to use the service have to have been diagnosed with Type 2 diabetes within the past six years, be aged 18-65 years old and have a BMI of over 27kg/m2 (or over 25kg/m2 in people of Asian, black or minority ethnic origin).10
Close support is required whilst following a very low-calorie diet, as sustained weight loss tends to last for around six months, but is then followed by weight regain.11 During the NHS LCDP, patients are closely supported by doctors, dietitians and nurses at their local GP practices. This support is offered via groupbased or one-to-one sessions (depending on COVID-19 restrictions), or remotely via an app, online or telephone, and lasts for 12 months. It is important that patients are made aware of the common side effects of a VLCD, such as lethargy, headaches, constipation, dizziness and hair thinning.2 Multivitamin deficiencies are also likely to occur. The NHS LCDP recognises that those with diabetes are more prone to developing unhealthy eating patterns, such as binge eating and so offers guidance to reintroducing food after the initial 12-week period.10,12
LOW-CARBOHYDRATE DIETS There remains scope to explore the optimal macronutrient ratio required to induce and help maintain weight loss in VLCDs. Diets lower in carbohydrate have been shown to increase hepatic insulin clearance and lower postprandial glucose compared with diets higher in carbohydrate content.13 This may reduce insulin exposure to tissues, increase the mobilisation of fat from specific adipose tissue deposits, and consequently induce short-term weight loss.14,15
There continues to be inconsistency in the definition of a low-carbohydrate diet,16 with definitions currently ranging from 50g to 130g carbohydrate per day17 (see Table 1). The European Food Safety Authority (EFSA) deem a VLCD to be ketogenic when carbohydrate content is below 30-50g/day and fat intake is 1530% of total caloric intake.18 It is notable that most studies using low-carbohydrate approaches use an ad libitum approach to caloric intake, whilst comparable diets are calorie-restricted only, with no specific macronutrient limits.
Low-carbohydrate diets have been associated with weight loss, consistent benefit in glycaemic control and sustained medication reduction in patients with Type 2 diabetes.19 A systematic review found lower carbohydrate diets induced greater weight loss and reductions in HbA1c at three months when compared with highcarbohydrate diets.20 Many meta-analyses have found diets low in fat to be inferior to those lower in carbohydrates and higher in fat for inducing weight loss, including ketogenic diets.21-24 Recent meta-analyses have also found lowcarbohydrate diets to have a beneficial effect on cardiovascular risk factors such as reducing lipid levels. However, further research is required in order to explore the long-term effects on these.25 Compared with an isocaloric, high-carb diet, patients consuming a low-carbohydrate diet have been found to expend 200-300 more calories daily, although more research into its metabolic advantages is warranted.26
A recent RCT identified that clinically significant weight loss and improvements in HbA1c were achieved in a low-carbohydrate diet group compared with a routine support group in a primary care setting.27 This was the first trial to attempt energy restriction to ~800kcal/ day using food rather than meal replacements, supported by generalists in routine care.27 This
suggests a low-energy, low-carbohydrate dietary intervention is feasible to be delivered in primary care; however, a longer-term trial is required to assess the long-term outcomes on weight and diabetes.
A new systematic review and meta-analysis suggests that patients with Type 2 diabetes who follow a strict low-carbohydrate diet for six months may experience greater rates of remission compared to other diets.36 Findings came from 23 randomised clinical trials looking at 1357 participants. The studies selected were used to evaluate low-carb diets (diets defined as less than 26% of daily calories coming from carbohydrates) and very low-carb diets (diets defined as less than 10% calories coming from carbohydrates) for at least 12 weeks in adults with Type 2 diabetes. Results showed that low-carb diets achieved higher diabetes remission rates at six months compared to patients on control diets, without adverse events. LCDs also led to improvements in weight loss, triglycerides and insulin sensitivity. However, at 12 months, many of these benefits had diminished. Very low-calorie diets were less effective, likely due to diet adherence.36 There is still debate about what counts as diabetes remission and other issues such as dietary satisfaction when following LCDs for the long run.
A concern regarding low-carbohydrate diets is the effect they may have on lipids, specifically LDL cholesterol. Predictably, lowcarbohydrate diets that replace carbohydrate with animal-derived protein and fat sources have been associated with higher mortality when compared with those replacing carbohydrate with plant-derived protein and fat sources.28 Systematic reviews have found a small increase in LDL with low-carbohydrate diets, but also increases in HDL and favourable decreases in triglycerides.29-31 This is likely due to some carbohydrates being replaced with omega-3 fats such as avocado, nuts and oily fish. The effect of low-carbohydrate diets on lipid profile is thought to be an individualised response. Fasting lipid profile, periodic lipid testing and shared decision-making are required if patients wish to take this dietary approach.32
Micronutrient content should, of course, be considered in VLCDs, but more recently the sources of macronutrients within these diets have been looked at.33 Meal replacements used in VLCDs are based on whey, soy, eggs and/or pea protein.34 Recent pilot research suggests that low-calorie ketogenic diets based on vegetable or whey protein result in a healthier microbiota composition than those containing animal proteins. The authors also found that ketogenic diets containing whey protein are more effective in maintaining muscle performance, possibly due to amino acids, such as leucine, enhancing muscle recovery and protein synthesis.35
CONCLUSION Patients following a lower carbohydrate diet do not necessarily adjust other key components of their lifestyle, eg, smoking cessation. They may also be likely to feel less motivated to exercise due to the consequential low-energy levels they experience secondary to a low-carbohydrate intake. Emphasis needs to be placed on a multifactorial healthy lifestyle approach.
Those with Type 2 diabetes wishing to follow a low-carbohydrate diet will also require close monitoring for hypoglycaemia and reduction of insulin or hypoglycaemic medications. Factors such as prescribed activity levels, palatable meal replacements and vitamin and mineral intake need to be considered carefully, along with motivational interviewing to ensure the behaviour changes are realistic and sustainable.
FEEDING THE SPECIAL NEEDS INFANT
This article will attempt to characterise the problems faced by the different subsets of infants with special needs, what feeding options are available and how this is managed. It will also look at the consequences of feeding difficulties and nutritional implications.
Feeding an infant can be challenging enough for parents in the first days, weeks and months, but when a baby is born with, or develops, ‘special needs’, feeding is much more challenging and can be the primer for years of feeding difficulties, a risk of malnutrition and poor growth.
The term ‘special needs’ (or additional needs) describes infants who require additional support for problems that may be medical, physical or developmental.1 There is no formal definition of special needs for infants, it is a heterogeneous group with a wide range of medical difficulties, chronic diseases and/or on a spectrum of developmental delay. Feeding is a complex combination and coordination of skills. It is the most difficult and physically demanding task an infant must do for the first few weeks, and even months, of life.2 A single swallow requires the use of 26 muscles and six cranial nerves working in harmony to move food and liquid through the body.2
Feeding infants with these additional needs requires both early intervention and regular support by a multidisciplinary team (MDT), including midwives, nursing staff, health visitors, paediatricians, GPs, speech and language therapists and occupational therapists. Paediatric dietetic support is needed for growth monitoring and intervention if oral intake is not sufficient and if specialist infant formula is required, or when alternative methods of feeding are needed, such as nasogastric tube feeding.
The mechanical skills that an infant needs to develop in order to feed safely include synchronous sucking, swallowing, breathing and oesophageal peristalsis to prevent food aspiration and to minimise unnecessary energy expenditure.2 The skill of sucking is of particular importance for establishing breastfeeding, and is developed in the third trimester of pregnancy (at approximately 32 to 36 weeks). Mature sucking consists of two components: suction and expression.2 Suction corresponds to the intraoral negative pressure that draws liquid into the mouth, or the creation of a vacuum. Expression is the compression and/ or stripping of the tongue against the hard palate. This tends to be developed before suction, which enables bottle feeding but not breastfeeding.
A large proportion of the infant population with special needs is likely to have dysphagia.3-7 Dysphagia in infants can be associated with a number of different conditions including: • being born prematurely (7% of births in the UK on average, 60,000 births per year)8 – the prevalence of dysphagia in premature infants is approximately 26%;6 • neurological deficits, eg, acquired traumatic brain injury (0.5% of births in the UK on average);9
Judy Paterson RD
Judy is a Freelance Paediatric Dietitian with 10 years’ clinical experience in the NHS. She is a Nutrition writer and Founder of Judicious Nutrition.
judicious_nutrition
diet_judy
REFERENCES Please visit: nhdmag.com/ references.html
• neuromuscular disorders, eg, muscular dystrophy;4,5 • chronic diseases, including chronic lung disease, cystic fibrosis, gastrointestinal disorders and congenital heart disease;10-11 • craniofacial conditions (0.16% of births in the UK per year on average), such as cleft palate or Pierre Robin Sequence;12 • congenital syndromes, eg, Down’s syndrome (0.1% of births in the UK per year).13
Infants who are being tube fed may be considered in this group alongside, given the adverse effects of tube feeding on oromotor feeding skill development, and a clear need for nutrition support.14 All of these infants will have considerable difficulty establishing breastfeeding and may also struggle with bottle feeding.
PRETERM INFANTS AND NEONATAL ICU/SPECIAL CARE BABY UNITS Infants born preterm and those who require intervention perinatally have a higher risk of feeding difficulties. The prevalence of feeding difficulties in premature infants born <37 weeks gestation is 10.5%.6
Respiratory and cardiovascular problems tend to result in infant feeding being affected in a number of ways, including:10,11 • reduced alertness; • respiratory illness, making breathing and swallowing more difficult; • bradycardia; • poor tolerance to feeds and volumes; • slow weight gain.
As shown in Figure 1, the characterisation of infants’ problems in the neonatal ICU highlights how the underlying diagnosis impacts on the risk of feeding problems through the course of hospital stay. There is no one unifying diagnosis of feeding disorder for these infants,14 which can make multidisciplinary treatment and a unifying approach problematic. Dysphagia symptoms as shown in Figure 2 are often separated into prefeeding, feeding and postprandial periods, making the diagnosis challenging. Problems with all phases of feeding can delay successful oral feeding.6 Adding to this, problems with feed tolerance and bradycardia/ desaturations can make discharge from hospital on oral feeds a distant probability.15 Between 7% and 45% of infants being discharged from NICU require nasogastric feeding at home.10
NEUROLOGICAL IMPAIRMENT AND CONGENITAL SYNDROMES16 Infants with neurological impairment and those with congenital syndromes may have a multitude of difficulties with feeding, including:
Difficulties during Oral Pharyngeal Phase
• Latching problems • Delayed initiation of suck response • Lack of sucking rhythm & lingual movement • Poor milk expression & extraction of milk • Lingual-palatal dyscoordination • Delayed initiation of pharyngeal swallow • Nasopharyngeal regurgitation • Silent aspiration • Gagging, arching & irritability • Respiratory rhythm disturbances • Peristatic failure • Autonomic changes • Painful swallowing • Oral aversion
Difficulties during Pharyngeal-Esophageal Phase
• Delayed initiation of pharyngeal swallow • Pharyngeal pooling • Nasopharyngeal regurgitation • Wet, gurgly breathing • Gagging, arching & irritability • Respiratory rhythm disturbances & stridor • Cough during feeding session • Apnea, bradycardia & desaturations • Autonomic signs & cardiorespiratory events • Laryngeal penetration & aspiration • Pharyngo-upper esophageal sphincter dyscoordination • Painful swallowing • Peristatic failure
Associations
• Overt or silent anterograde aspiration • GERD & its consequences • Retrograde aspiration • Airway/lung disease • Oral aversion • Behavioural feeding problems • Growth failure • Developmental delays
• hypotonia – poor tone of the oropharyngeal muscles resulting in weak or uncoordinated sucking and swallowing;17 • reduced alertness and energy for feeding; • hyperextension of the neck and shoulders, compromising tongue positioning and jaw movement;16 • respiratory infection, making breathing and swallowing more difficult; • slow weight gain; • risk of breastfeeding complications; • developmental delay further compounding the development of feeding skills.
OROFACIAL ANOMALIES Orofacial structural problems impact on feeding in many ways; there is often difficulty forming a seal around the breast.18 If the oral cavity is not adequately separated from the nasal cavity during feeding, babies are unable to generate a vacuum to remove milk from the breast or bottle.18 As a result, these babies experience fatigue during breastfeeding, prolonged breastfeeds and impaired growth and nutrition. The size and location of the baby’s cleft lip and/ or palate will influence whether or how they can breastfeed. There is evidence that breastfeeding can begin or recommence after cleft lip and cleft palate surgery.18
HOW TO FEED AND INTERVENTIONS The key thing to highlight about feeding the special needs infant is that early intervention is absolutely vital and a multidisciplinary approach is essential.
Breastfeeding
Breastfeeding may be more difficult for infants with special needs, due to many factors including a reduced or absent ability to suck. However, it is important to highlight that it is not impossible and that expressing breast milk should be supported not only during inpatient stay,19-20 but also at home. It is vital that the MDT encourage mothers and support them to initiate breastfeeding wherever possible. Breast milk feedings (expressed breast milk – EBM) provide nutritional, neurological and immunological advantages to both neonates and infants,18-20 with upkeep of breast milk expression a difficult but important job for mothers and caregivers until breastfeeding can be established.20 Hospital lactation consultants are key figures in supporting mothers and the team in this process. Preterm infants and those with poor growth who are receiving breast milk may need their feeds fortified with specialist products provided only during the inpatient period.21
Evaluation of breastfeeding complications
Early assessment and intervention by the MDT are required to assess the feeding problems and decide on an appropriate management strategy. Dietitians may or may not be involved in this process, as it depends on when the referral is received.
Each infant and their likelihood of breastfeeding success should be assessed. If breastfeeding is not possible, or exclusive breastfeeding is not possible, mothers should be supported to achieve a full milk supply for breast milk feeding.20 Where feeding at the breast is difficult or impossible, or if mum–baby separation exists, regular breast expression should begin early after birth.
It should be noted that maintenance of breast milk expression in the large proportion of infants on, for example, NICU, continues to be problematic.20 Sadly, the pandemic has had worsening effects on breastfeeding rates given the lack of support available.22
Advice for mothers in establishing and maintaining a milk supply should be provided.19-20 If baby is unable to suck, milk supply will be at risk, so advice for increasing supply will be needed. If the baby is able to breastfeed, a speech and language therapist or occupational therapist may be required to help optimise feeding.
Support of chin, cheek and jaw movement may assist in facilitating a stronger sucking pattern if oral motor control is low or sucking is weak or disorganised.19-20 Modification of positioning and attachment may help breastfeeding. Different positions may help babies with a cleft lip and/or palate18 or hypotonia.17 Supplementation of feeds may be necessary.21 If partially breastfeeding, the mum will be required to express regularly and supplement breast feeds via an alternative device.
Continual monitoring of nourishment and hydration, including volume, frequency of milk transfer and weight gain while establishing the feeding method, is required.
Bottle feeding
Bottle feeding may need adaptation in the form of special teats, which are adapted to allow babies to feed even with a very weak suck.20 Bottle feedings can incorporate EBM or first infant formula milk/other formula for special medical purposes.
Nasogastric tube feeding
Tube feeding may be necessary for infants who are unable to achieve sufficient intakes with either breast or bottle feeding. However, it is problematic in that an infant’s feeding skills are not developed by the time they have the feeding tube and this can lead to oral feeding aversions unless a lot of practice and work is put in to avoid this.24 In hospitals, speech and language therapists may suggest ‘dummy dips’, i.e. regularly putting the bottle teat or dummy in infant formula and establishing baby’s latch on to this. Dummy dips can provide the opportunity for purposeful swallows that start the process of swallowing in the course of feeding. Using nonnutritive sucking is important for helping the infant to achieve the quiet alert state appropriate for feeding. It can also support parent learning on how to interpret differing infant states and thus support parent-bonding.25 An oral stimulation programme put in place by speech and language therapists and nursing staff can help to advance oral feeding skills faster than without.25
Complementary feeding (weaning onto solids)
Starting on solids can be a tricky time for parents and they will need support from the healthcare team.26 Depending on the findings of multidisciplinary assessment, feeding can usually be managed safely with correct positioning, consistency of food and drink, special utensils including bottles, cups, or cutlery and nutritional advice.
Firstly, identifying the right time for starting solids may be difficult for parents due to several factors including developmental delay, oral
Table 1: Long-term consequences of feeding and swallowing disorders
Food aversion
Oral aversion
Aspiration pneumonia and/or compromised pulmonary status
Undernutrition or malnutrition
Dehydration Gastrointestinal complications such as motility disorders, constipation and diarrhoea Faltering growth – poor weight gain velocity and/or undernutrition Rumination disorder (unintentional and reflexive regurgitation of undigested food that may involve re-chewing and re-swallowing of the food) Ongoing need for enteral or parenteral nutrition Psychosocial effects on the child and his or her family Feeding and swallowing problems that persist into adulthood, including the risk for choking and malnutrition
aversive behaviour and low muscle tone, which can prevent infants from developing a safe posture for feeding. However, there are usually signs that babies are ready for starting on solids, such as being able to hold their head in a stable position.26 Infants may need special adaptations, such as extra support to enable them to achieve stable positioning.
Parents are likely to need preparation for weaning, as it should be started at around the same time for infants with typical development. However, it is likely to take longer to reach family meals and independent eating. Again, a multidisciplinary approach is best. Occupational therapists can advise on seating or appropriate equipment to use. A specialist speech and language therapist may advise on all aspects of feeding, including how to encourage the oral-motor movements required for feeding, for example by giving jaw support, encouraging lip closure and tongue lateralisation.4,5
Due to the heterogeneous nature of this group, the introduction of solid foods may have already started and dietitians only receive referrals when weaning is not progressing or weight gain is poor.
WHAT IS THE IMPACT OF FEEDING DIFFICULTIES ON INFANTS?
Nutritional deficiencies
Dysphagia and feeding difficulties increase the risk of reduced energy and nutrient intake, and poor growth, potentially leading to faltering growth.27-28 Faltering growth in infants may be detrimental to the long-term health of the child, as its effects go beyond physical growth, with potential impacts on psychomotor development and neurological development.27 There are also recognised effects of reduced nutrient intake on the immune, skeletal and cardiovascular systems.27
Gastrointestinal disease is common in this group of infants and will impact on their ability and desire to take in adequate nutrition. This in turn can have a great effect on the mother–infant relationship, with refusal to feed causing great distress.
Feeding difficulties can unfortunately develop into feeding disorders; the prevalence of such is increasing because of the improved survival rates of children with complex and medically fragile conditions.28-30 Table 1 lists examples of the consequences of feeding and swallowing disorders.1,26,30
CONCLUSION A multidisciplinary approach, including specialist paediatric dietitians, is crucial to ensure optimising growth and nutrition in this vulnerable group of patients due to their problems with feeding difficulties and disorders. Dietitians provide support with feeding skill development, monitoring growth and nutritional status, optimising nutrition for catch-up growth and supporting parents with feeding.
