A nourishing plant-based diet

A plant-based diet includes vegetables, wholegrains, legumes, nuts, seeds and fruits, with no or limited animal products. During periods of illness it is important that your diet is well balanced to help your body recover. We hope the information on this page will support you in that.

A balanced diet

Diets based mostly on plant foods should be planned to make sure they include a variety of nutrients. This is especially important if you are avoiding animal-derived foods (including eggs and dairy).

In the next section we list the nutrients needed for a well-balanced diet, and give examples of foods that include them.

Calcium

Needed for bone and teeth health, and reducing bone fractures. It also supports your nervous system, and is involved in controlling muscles and blood clotting.

Food sources: plant-based dairy alternatives with added calcium, calcium set tofu, dried figs, nuts, leafy green vegetables (kale, pak choi, spring greens, okra), red kidney beans, chia seeds, sesame seeds and tahini.

Vitamin D

Needed for bone, teeth and muscle health.

Exposing skin to sunlight between April and September can help our body make vitamin D. Over autumn and winter months, it’s important to include foods rich in vitamin D. These include mushrooms and fortified foods, such as vegetable spreads and breakfast cereals.

You may also need to consider vitamin D supplements. Please speak to your dietitian for more information.

Omega 3 fatty acids (alpha linolenic acid) and omega 6 fatty acids (linoleic acid)

These are important for our immune system, brain, nervous system and eyes. Our bodies cannot make these oils, so it is essential to include them in your diet.

• Omega 3 food sources: chia seeds, ground linseed, rapeseed oil and walnuts.
• Omega 6 food sources: hemp, sunflower and pumpkin seeds, walnuts and soya spread.

Iodine

Needed to make thyroid hormones which are involved in many body processes, including growth and metabolism.

Food sources: sea vegetables such as seaweed (but only include these in your diet once a week due to potentially high levels of iodine), nuts and bread. Some fruits and vegetables also contain iodine. The amount of iodine they contain depends on the amount of iodine found in the soil they are grown in.

If you are taking an iodine supplement, please discuss this with your dietitian.

Selenium

Needed for the immune system, reproduction and to prevent damage to cells.

Food sources: 2 brazil nuts a day will meet your requirements. Other sources include grains, seeds and nuts.

Zinc

Needed for making new cells, wound healing and fighting infections.

Food sources: beans, chickpeas, lentils, tofu, walnuts, cashew nuts, ground linseed, hemp, chia and pumpkin seeds, wholemeal bread and quinoa.

Vitamin B12

Needed to reduce fatigue, anaemia and nerve damage.

Food sources: fortified foods such as breakfast cereals, yeast extract, soya yoghurt, and plant-based milks with added vitamin B12.

Iron

Needed for making new blood cells, carrying oxygen around the body and preventing anaemia.

Food sources: fortified breakfast cereals, chickpeas, beans, lentils, tofu, cashew nuts, ground linseed, chia, hemp and pumpkin seeds, kale, dried apricot, figs and quinoa. Try to eat iron-rich foods with foods rich in vitamin C to help absorption. These include peppers, broccoli, cabbage, oranges and grapefruit.

Protein

Needed for muscle and bone health, fighting infection, growth and repair of body tissue.

Food sources: lentils, beans, chickpeas, nuts, nut butters, tofu, meat substitutes (such as soya, tempeh or vegan Quorn®), some plant- based milks and dairy products.

Further information

You can find more information about these and other nutrients on The Vegan Society and British Dietetic Association websites. 

It may be difficult to get all the energy and nutrients you need if you have poor or no appetite. Here are some tips to help you during this time:

• You may find it easier to manage smaller, more frequent meals and snacks throughout the day rather than three large meals. Try eating every two to three hours.
• Try to eat something when your appetite is best, even if it’s at unusual times.     
• If your taste changes, try different foods to see what you like best. This may be a food that you previously didn’t like.

• Avoid filling up on large servings of vegetables or salads as they don’t provide many calories.
• Don’t drink lots of fluids with your meals, because they will fill you up leaving less room for nutritious food; the best time to drink fluids is half an hour before or after eating.
• Aim to choose foods that are high in calories and protein to help you meet your requirements.

Ways to increase calories in meals include:

• Add dairy-free spread or olive oil to potatoes, vegetables and pasta.
• Use extra oil in cooking; try frying and roasting over grilling or steaming.
• Add vegan mayonnaise and dressings to salads and vegetables.
• Add ground nuts or nut butter to sauces, soups and desserts.
• Add tinned coconut milk to curries, sauces and soups.
• Add extra golden or maple syrup, jam or sugar to drinks, desserts and cereals.
• Aim to eat a dessert at least once or twice a day.
• Add almond, coconut or soya yogurt or ice cream to desserts.
• Blend avocado, tofu or soaked cashews in with smoothies and soups.
• Make up a plant-based custard powder with non-dairy milk and sugar, and add to desserts.

Non-dairy milk alternatives fortified with protein, calcium and vitamin D can be a great replacement for full-fat cow’s milk. The following table contains a comparison between full-fat cow’s milk and various plant-based drinks. 

If you can’t face a large meal, you may find it easier to manage a snack or a lighter meal instead. Here are some high-calorie, high-protein snack and light meal ideas:

Snacks

• An apple or banana with 1 tbsp peanut butter (145kcal, 4.5g protein)  
• A 25g packet of crisps (130kcal, 1.5g protein)
• A handful of Bombay mix (around 50g – 270kcal, 5g protein)
• A handful of mixed nuts (around 40g – 260kcal, 8.5g protein)  
• Two biscuits, such as Ginger Nuts®, Hobnobs® or bourbons  (95–145kcal, 1–2g protein
• A toasted pitta bread with 2 tbsp hummus or baba ghanoush (250kcal, 7g protein)
• 125g pot of soya yogurt with 1 tbsp maple syrup and one serving of tinned or fresh fruit (175kcal, 5g protein)  
• Two slices of fruit loaf or a tea cake with 1 tbsp dairy-free spread and 1 tbsp jam (310kcal, 6g protein)  
• 75g roast edamame beans (315kcal, 27g protein)  
• Three falafels with 50g hummus (310kcal, 9g protein).   

Light meals  

• 100g vegan nuggets (such as Quorn®) with 1 tbsp vegan mayo (250kcal, 12g protein)
• A slice of toast with 1 tsp dairy-free spread and a 200g tin of baked beans (310kcal, 12.5g protein)  
• A slice of toast with 1 tsp dairy-free spread, topped with scrambled tofu (see recipe below –  510kcal, 20g protein)  
• Two vegan sausages with a handful of oven chips and 1 tbsp vegan mayo (410kcal, 19g protein)  
• A medium baked potato with 2 tsp butter and various toppings: mashed avocado, baked beans, vegan chilli, hummus, mashed peas, vegan cheese  (170–330kcal, 3–12g protein)
• A small bowl of dhal with chapatti  (300kcal, 14g protein)  
• 30g porridge oats cooked with 125ml soya milk, topped with 5g ground linseed and 1 tbsp jam (300kcal, 14.5g protein)  
• Half a can tinned vegetable soup blended with 40g soaked cashew nuts  (325kcal, 10.5g protein)  
• A small bowl of cereal with non-dairy milk, for example two wheat biscuits with 125ml soya milk (240kcal, 13g protein). 

Fillings for sandwiches/bagels/wraps  

• Plain bagel with 100g crumbled firm tofu mixed with 2 tbsp vegan mayo (465kcal, 17.5g protein)  
• Two slices of white bread with 1 tbsp peanut butter and 1 tbsp jam (320kcal, 9g protein)  
• A plain tortilla wrap with 1 tbsp vegan mayonnaise, one small avocado, one sliced tomato and two slices of vegan cheese (535kcal, 7g protein)
• Plant-based burger in a bun with 1 tbsp vegan mayo  (350kcal, 12.5g protein) 

Desserts  

• Two pancakes with 2 tbsp maple syrup and half a banana  (340kcal, 6.5g protein)  
• A pot of jelly with two scoops of non-dairy ice cream and 30g chopped hazelnuts  (485kcal, 7.5g protein)  
• An individual apple and blackcurrant pie (around 60g) with custard  (370kcal, 6.5g protein)  
• A small bowl of coconut rice pudding with jam (see recipe below –  660kcal, 5.5g protein)  
• Three pieces of Turkish delight (about 35g – 117kcal, 0.5g protein)
• Puff pastry fruit tart – one quarter sheet of vegan rolled puff pastry, one sliced apple, 2 tbsp sugar, served with non-dairy ice cream  (450kcal, 5g protein).

You can use vegan protein powders to fortify foods and drinks to increase the calories and protein in your diet. An average serving of protein powder provides 100–120kcal and 15–20g protein.

Please note: protein powders don’t include all nutrients needed for a balanced diet. For this reason, you should use them to supplement your diet, and not to replace your meals.

You can find protein powders in most health food shops and online. They are available in a range of flavours, and you can add them to smoothies, milkshakes or any of the nourishing drink recipes included in this booklet. Unflavoured options are also available which could be added to soups and sauces.

If you need support with getting more protein into your diet or are still losing weight, please speak to your dietitian. They may recommend some nutritional supplement drinks that are available on prescription.

The recipes we have included below are just suggestions; you may find that you are able to eat a bit more or a bit less than the quantities given. You can also substitute any ingredients you don’t like for something else. If you are too tired to cook or prepare food, you can use convenience foods such as frozen and microwaveable ready meals.

Breakfast  

Granola – 13 servings

• 400g jumbo oats
• 250g mixed nuts, chopped
• 150g mixed dried fruit, chopped
• 2 tsp cinnamon
• 150g coconut oil, melted
• 100ml maple syrup. 

Preheat oven to 180°C/fan160°C/gas 4. Mix all the ingredients together except the maple syrup and dried fruit. Spread the mixture out on two large baking trays and drizzle over the syrup. Bake in the oven for 20 minutes, stirring halfway through. Leave to cool and then add dried fruit. Store in an airtight container. Serve with non-dairy milk or yogurt.

• One serving (about 75g) with 125g soya yogurt provides 468kcal, 12.5g protein
• One serving (about 75g) with 200ml soya milk provides 484kcal, 13.5g protein.   

Coconut and banana pancakes – 8–10 servings

Mix 150g plain flour, 50g ground almonds, 2 tsp baking powder and 6 tsp caster sugar in a bowl. Slowly add 400ml coconut milk and whisk to make a smooth batter. Heat 1 tsp vegetable oil in a frying pan and add 2 tbsp batter per pancake. Add 3–4 slices of banana into each pancake and cook until bubbles appear on the surface. Carefully flip and cook the other side for 1 minute. Repeat with all the batter.

Serve with 1 tbsp maple syrup each, some coconut flakes and any remaining banana slices.

1 serving provides 303kcal, 4g protein.

Scrambled tofu on toast – 2 servings

Heat 1 tbsp oil in a frying pan and fry a finely sliced onion for 10 minutes until soft and golden brown. Stir in 1 crushed garlic clove, half tsp turmeric, half tsp cumin and half tsp paprika, and cook for 1 minute.

Roughly mash 280g tofu in a bowl using a fork. Add to the pan and fry for 3 minutes. Turn up the heat, add in 100g cherry tomatoes and cook for 5 minutes until they begin to soften. Fold through a small bunch of parsley. Serve half on a slice of toast, sprinkle over the cashew nuts and drizzle with 1 tbsp olive oil.

1 serving provides 510kcal, 20g protein.  

Soups  

To give ready-made soups a boost, you could add in 1 scoop unflavoured vegan protein powder, 2 tbsp soya cream, 100g silken tofu or 30g ground almonds, and blend until smooth.  

Mixed bean soup – 6 servings

Cover 100g cashew nuts with boiled hot water and soak them for minimum 2–3 hours. Heat 3 tbsp oil in a pot, add 150g chopped onion and cook for 5 minutes until soft. Chop 3 garlic cloves, 1 stick of celery, 1 large carrot and 1 small fennel bulb, add to the pot and cook for 2 minutes. Add 1x400g tin chopped tomatoes and boil for 2 minutes.

Add 900ml vegetable stock and simmer for 15 minutes until vegetables are tender. Add 3x400g tins mixed beans (drained) and 100g drained cashew nuts. Blend until smooth. If needed, add 100ml more stock.

1 serving provides 329kcal, 12g protein.   

Sweet potato and lentil soup – 6 servings

Heat 3 tbsp oil in a pot, add 200g chopped onion and 3 crushed garlic cloves and cook for 5 minutes. Add 600g chopped sweet potato, 200g dried lentils, 400g coconut milk and 800ml vegetable stock. Simmer for 30 minutes, until the sweet potato is cooked. Blend until smooth.

1 serving provides 384kcal, 11g protein.  

Parsnip, carrot and ginger soup – 6 servings

Cover 50g cashew nuts with boiled hot water and soak for minimum 2–3 hours. Heat 4 tbsp oil in a pot, add 1 chopped onion and cook for 5 minutes. Add 2 large parsnips, 3 medium carrots (both chopped) and 20g fresh grated ginger, and cook for 5 more minutes. Add 1 litre vegetable stock and 2x400g tins of drained chickpeas. Bring to the boil.

Turn down heat and simmer for 30 minutes, until vegetables are soft. Add 150ml fresh orange juice, 200ml coconut milk, 50g drained cashew nuts and 300g silken tofu, and blend until smooth.

1 serving provides 357kcals, 11.5g protein.

Main meals  

Quinoa-stuffed butternut squash – 2–3 servings

Pre-heat oven to 200°C/fan 180°C/gas 6. Halve 1 medium butternut squash, scoop out the seeds and score the flesh with a sharp knife. Place on a baking tray, drizzle with 2 tbsp olive oil, season with salt and pepper, and bake for 40 minutes.

Remove from the oven. Add 1 chopped red pepper to the tray and cook for a further 10 minutes. Mix 50g pitted olives (halved) with 2 chopped spring onions, 150g pre-cooked quinoa, 50g toasted pine nuts, 1 small chopped carrot, the juice of half a lemon and the cooked peppers. Spoon the mixture into the butternut squash and return to the oven for 10 more minutes before serving.

1 serving provides 563kcal, 12g protein.   

Caramelised red onion and olive puff pastry tart – 4 servings

Pre-heat oven to 220°C/fan 200°C/gas 7. Heat 2 tbsp olive oil in a frying pan and fry 2 large chopped red onions for 10 minutes until golden and soft. Add 3 tbsp brown sugar and 2 tbsp balsamic vinegar, and cook for a further 5 minutes until it’s syrupy. Leave to cool. Unroll 375g sheet of ready-rolled puff pastry on a baking tray and score a line round the edge (about 1cm in) to create a border.

Fill the middle with onion mixture. Scatter 200g pitted black olives (halved) and 50g pine nuts over the onions. Season and drizzle with 2 tbsp olive oil. Bake for 15 minutes until the pastry is risen and golden. Cut into quarters and serve.

1 serving provides 773kcal, 10g protein.   

Vegan casserole – 4 servings

Pre-heat oven to 220°C/fan 200°C/gas 7.

Toss 2 diced red or yellow peppers, 1 diced courgette and 1 diced carrot with 2 tbsp olive oil. Roast for 25–30 minutes, turning half way. Set aside when done.

Boil 600g baby potatoes (halved) until almost fully cooked, strain and set aside. Sweat 1 thinly sliced red onion and 3 crushed garlic cloves for 15 minutes, stirring occasionally. Add 2x400g tins of chopped tomatoes, 2 tbsp tomato puree and a half tsp dried oregano.

Cook for 20–30 minutes on a low heat until the sauce has thickened. Stir in the roasted vegetables, cooked potatoes, 1x400g tin of butter beans, 1x400g tin of kidney beans, 1x400g tin of chickpeas (all drained). Stir in 1 tsp brown sugar and pine nuts and serve.

1 serving provides 633kcal, 25g protein.   

Tomato and butternut squash pasta – 4 servings

Cover 50g cashew nuts with boiled hot water and soak for minimum 2–3 hours. Heat 3 tbsp olive oil in a pan. Add 1 medium, finely chopped onion and 2 small, peeled and grated carrots and cook for 5 minutes. Add 1 peeled and finely chopped butternut squash and cook for another 5 minutes. Add 800g passata and 200g red split lentils and bring to the boil. Turn down the heat, cover and cook for 30 minutes.

Meanwhile, cook 200g pasta according to the packet instructions. Add 50g soaked and drained cashew nuts to the sauce and blend until smooth. Mix sauce in with the pasta and serve topped with 120g vegan grated cheese.

1 serving provides 647kcal, 23g protein.   

Mexican beans and avocado on toast – 4 servings

Mix 270g quartered cherry tomatoes, a quarter chopped onion, juice of half a lime and 1 tbsp olive oil and set aside. Fry the remaining onion in 2 tbsp oil until soft. Add 2 minced garlic cloves and fry for 1 minute, then add 1 tsp ground cumin and 1 tsp chilli flakes and stir. Add 2x400g tins of drained black beans and a splash of water, stir and cook gently until warmed through.

Stir in most of the tomato mixture and cook for 1 minute, then add most of a small bunch of coriander. For one serving, toast a thick slice of bread and drizzle with some olive oil. Plate up with a quarter of the beans, half an avocado, and some of the remaining tomato mixture and coriander.

1 serving provides 478kcal, 13g protein.   

Desserts and snacks  

Chocolate avocado mousse – 6 servings

Melt 100g dark chocolate in a heatproof bowl over a pan of shallow simmering water. Stir in 4 tbsp maple syrup, 2 tsp vanilla extract, 5 tbsp soya milk and 2.5 tbsp cocoa powder until smooth. Add the mixture to a blender with 2 large ripe avocados (peeled and destoned) and blend until smooth.

Divide the mixture between 6 serving bowls and chill for 3–12 hours before serving. Divide 100g chopped pistachios between each bowl just before serving.

1 serving provides 350kcal, 7.5g protein.   

Vegan chocolate orange pots – 6 servings

• 200g 70% dark chocolate
• 700g silken tofu
• 160g maple syrup
• Zest of 1 orange
• 1 tsp vanilla extract
• 6 ginger nut biscuits, crumbled. 

Melt chocolate in a bowl over a pan of simmering water. Wrap tofu in a clean tea towel and squeeze out excess liquid. Add tofu to a blender with the orange zest and vanilla extract, and blend until smooth. Add the melted chocolate and blend again until well combined. Divide the mixture into bowls and top with the biscuit crumbs. Chill for 15 minutes before serving.

1 serving provides: 409kcal, 11g protein.   

Coconut rice pudding – 4 servings

Preheat oven to 200°C/fan 180°C/gas 6. In a large ovenproof dish, stir 80g golden caster sugar, 800ml tinned coconut milk, zest of 1 lemon and seeds of 1 vanilla pod with 160g washed pudding rice until combined. Bake in the oven for 2 hours or until the rice is tender, stirring halfway through. Serve each portion with a tablespoon of jam.

1 serving provides 660kcal, 5.5g protein.   

Raspberry chia pudding – 2 servings

• 75g chia seeds
• 300ml non-dairy milk (such as soya milk)
• 100g raspberries
• 1 tsp lemon juice
• 3 tbsp maple syrup
• 1 medium banana
• 2 tbsp desiccated coconut. 

Divide the chia seeds and milk between two serving bowls and stir well. Refrigerate for a few hours or until the seeds swell and thicken the milk, stirring regularly to make sure the chia seeds are well distributed. Blend the raspberries, lemon juice and 1 tbsp maple syrup. Divide the mixture between the two chia seed bowls and stir through.

Top each bowl with half a sliced banana, 1 tbsp dessicated coconut and 1 tbsp maple syrup.

1 serving provides 470kcal, 15g protein.   

Fruit and nut flapjacks – 16 squares

• 350g porridge oats
• 80g ground almonds
• 100g mixed nuts, roughly chopped
• 200g mixed dried fruit, roughly chopped
• 50g mixed seeds
• 200g dairy-free butter
• 175g golden syrup
• 200g light brown soft sugar. 

Preheat oven to 180°C/fan160°C/gas 4. Grease and line a 23cm/9in square cake tin. In a large bowl, mix together the oats, ground almonds, nuts, fruit and seeds. Place the butter, golden syrup and brown sugar in a pan and heat slowly, stirring occasionally until melted.

Pour this mixture into the dry ingredients and mix until thoroughly combined. Tip the mixture into the tin, spread it out and press down firmly until well compacted. Bake for 25–35 minutes or until the top and edges are golden brown (it will still be a little soft to touch). Leave to cool for 10 minutes in the tin then turn out and slice when completely cool.

1 square provide: 380kcal, 6g protein.   

Peanut butter banana bread – 8 servings

• 3 ripe bananas, peeled
• 50g peanut butter
• 200g light brown sugar
• 100ml vegetable oil
• 250g self-raising flour
• 50g ground almonds
• 2 tsp cinnamon.

Preheat oven to 180°C/fan160°C/gas 4. Line a 2lb loaf tin with baking paper. Mash the bananas in a large mixing bowl, add the peanut butter, sugar and oil and mix thoroughly. Mix the flour, ground almonds and cinnamon in another bowl, add it to the banana mixture, and stir to combine.

Pour the cake mix into the tin and bake for 1 hour or until a skewer inserted into the middle comes out clean. Leave to cool on a wire rack before serving.

1 serving provides 423kcal, 7g protein.   

Smoothies and nourishing drinks  

Apple and avocado smoothie  – 1 serving

• 1 apple, peeled, cored and roughly chopped
• 1 small avocado
• juice of half a lime
• 1 tbsp maple syrup
• 150ml soya milk
• 50g silken tofu
• Handful of ice. 

Blend all the ingredients together until smooth.

Provides 374kcal, 11g protein.  

Chocolate, banana and peanut butter smoothie – 2 servings

• 300ml soya milk
• 2 tbsp vegan chocolate spread
• 1 tbsp peanut butter
• 1 medium banana, peeled and frozen
• 2 tbsp ground flaxseed
• Handful of ice. 

Blend all ingredients together until smooth.

1 serving provides 371kcal, 13g protein.   

Strawberry and coconut smoothie – 2 servings

• 150g frozen strawberries
• 1 medium banana
• 100ml tinned coconut milk
• 50g unsalted cashew nuts
• 50g oats
• 300ml soya milk.

Blend all ingredients together until smooth.

1 serving provides 480kcal, 14g protein.   

Fruity float – 1 serving

• 100ml fresh fruit juice
• 100ml lemonade
• 1 tsp sugar
• 1 scoop vegan ice cream. 

Mix all the ingredients together and serve chilled.

Provides: 258kcal, 3g protein.   

Nourishing coffee – 1 serving

• 150ml fortified plant-based milk
• 2 tbsp soya cream
• 1 tsp instant coffee. 

Mix coffee with 50ml boiling water until dissolved. Warm the milk in the microwave then stir into the coffee. Add the cream and mix well.

Provides 169kcal, 6g protein.   

Nourishing hot chocolate – 1 serving

• 250ml fortified plant-based milk
• 2 tbsp soya cream
• 2 tsp dairy-free drinking chocolate powder
• 6 vegan marshmallows. 

Mix the chocolate powder with 50ml boiling water until smooth and combined. Warm the milk then stir into the chocolate mixture. Add the cream and mix well, then top with the marshmallows.

Provides 397kcal, 12g protein.   

Fortified plant-based milk

• 1L plant-based milk of your choice
• 100g soya milk powder (available online). 

Mix the milk powder with a small amount of milk to make a paste. Then add the rest of the milk. Once made, store it in the fridge and use within the use-by date on the milk carton.

How to use:

• Drink on its own
• Make into a hot milky drink, such as hot chocolate, malted milky drinks, coffee, chai latte
• Make into a cold milkshake using plant-based milkshake powder or syrup to flavour, and a scoop of plant-based ice cream
• Add to cereals, soups, sauces and puddings, and use in cups of tea. 

250ml fortified soya milk provides 220kcal, 9g protein.  

Breakfast    

Granola with soya milk         

Glass of fresh orange juice         

Tea or coffee    

Snack        

Pitta bread with hummus         

Two biscuits         

Tea or coffee

Lunch    

Sweet potato and lentil soup         

Raspberry chia pudding         

Water or fruit squash

Snack        

Chocolate, banana and peanut butter smoothie

Dinner    

Tomato and butternut squash pasta         

Chocolate orange pot         

Water or fruit squash

Snack      

Nourishing hot chocolate

The Vegan Society – Nutrition overview

vegansociety.com/resources/nutrition-and-health/nutrition-overview

NHS – The vegan diet

nhs.uk/live-well/eat-well/the-vegan-diet

British Dietetic Association – Plant-based diet fact sheet

bda.uk.com/resource/plant-based-diet.html

University College London Hospitals NHS Foundation Trust cannot accept responsibility for information provided by external organisations.

Your dietitian can offer you further dietary advice tailored to you and your needs.

Tel: 020 3447 9289 (Monday to Friday, 9am to 5pm)

Email: uclh.dieteticsteam@nhs.net

Website: uclh.nhs.uk/dietetics