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The classic mistakes made on special diets

Woman face-palming her forehead after making a mistake

Have you gone ‘dairy free’? Need to avoid gluten? Trying to lose weight? If you’re on a special diet, there’s a possibility you’re making one of these common mistakes, says Dr Sue Shepherd.


Mistake: Not replacing meat

Simply removing meat is not the way to approach a vegetarian diet. Unless meat is replaced by suitable alternatives, your diet may lack many essential nutrients including protein and iron. Plan your diet to include:

  • protein sources, such as legumes (lentils, chickpeas, beans), quinoa, tofu, nuts and seeds;
  • non-haem iron sources, like spinach and other leafy green vegetables, and iron-fortified cereals.

Remember, contrary to the impression Popeye left us with, spinach isn’t a rich source of iron, due to its low bioavailability. Boost your absorption of iron from plant-based sources by eating foods rich in vitamin C (tomato, capsicum, oranges, berries) at the same time.


Mistake: Eating mushrooms to get your vitamin B12

There is a myth that mushrooms are a rich source of vitamin B12 – not true! It’s the soil left on unwashed mushrooms that contain vitamin B12-rich bacteria. Vitamin B12 is an essential nutrient with an important role in our nervous system and our blood. It is only found in foods of animal origin, so many vegans may be at risk of deficiency. If you are vegan, make sure you discuss your options with a medical practitioner – they may suggest oral or injected B12 supplements.

Dairy-free diet

Mistake: Missing your calcium

Dairy foods are usually the greatest contributors of calcium to our diets – so going dairy-free can put you at higher risk of becoming calcium deficient. ‘Dairy’ means ‘cow’, so people following a dairy-free diet can generally consume goat, sheep or buffalo milk, cheese or yoghurt, which have comparable calcium contents to dairy sources – just make sure you’re using reduced-fat variations where possible. You can also use soy, rice or oat milks, but keep in mind that these aren’t naturally high in calcium, so you’ll need to choose products that are calcium-fortified.

Mistake: Going ‘full-fat’

Going dairy-free means you have less ‘low-fat’ varieties available to you, both because it’s often difficult to find low-fat sheep and goat milk products; and although there are lots of great low-fat soy milks available, you’re unlikely to find one at your local coffee shop! This can mean you end up consuming more kilojoules than desired, and significant amounts of saturated fat – the ‘bad’ fat – from full-fat animal milks. (Full-fat soy, on the other hand, contains mostly unsaturated fat, including a good amount of omega- 3s.) Try to choose lower-fat variations where you can, and choose reduced-fat versions to drink at home.

Lactose-free diet

Mistake: Avoiding just dairy

A lactose-free diet is different to a dairy-free diet! Lactose is a double sugar made up of two smaller sugars (glucose and galactose). Most people following a lactose-free diet do so because they have a lactose intolerance (also called lactase deficiency), where the body does not make enough of the enzyme to break down lactose. Lactose is a sugar that naturally occurs in the milk from any mammal, including cow, sheep, goat and buffalo, so you’ll need to avoid all of these.

Mistake: Avoiding all products made from milk

Many people believe they have to avoid every food made from cow’s (and other animals’) milk. But many lactose-free milks and yoghurts are now available, so you don’t need to compromise your calcium intake. Moreover, most people with lactose intolerance can tolerate up to 4g of lactose per meal or snack, which means small amounts of lactose-containing products can usually be enjoyed, as long as they’re spread throughout the day. Finally, some milk products, such as hard cheeses (eg. cheddar, tasty, edam, pecorino and parmesan) can actually be enjoyed without restriction as they are lactose-free.

Diets for Irritable Bowel Syndrome (IBS)

Mistake: Sticking to a ‘safe’ diet

There are many diets promoted for the management of symptoms of Irritable Bowel Syndrome (IBS). Many sufferers use ‘trial and error’ to identify foods that trigger their symptoms, and end up restricting themselves to only a handful of ‘safe’ options. Unfortunately, if you omit individual foods or whole food groups, and aren’t replacing them with foods containing similar nutrients, you’re putting yourself at risk of nutritional inadequacy. A good way to counter this is to trial a ‘low-FODMAP ’ diet, which is recognised internationally as an effective diet for IBS, and likely to help you meet all your nutritional requirements, because it provides suitable alternative foods to those you should avoid. (See HFG February 2010 for more information.) To help ensure you are eating foods that provide you with all your nutrients, whilst still managing your symptoms, consult with an Accredited Practising Dietitian.

Mistake: Starting a gluten-free diet before being tested for coeliac disease

Because the symptoms of undiagnosed coeliac disease are similar to symptoms of IBS, many people put themselves on a gluten-free diet as an attempt to manage their IBS symptoms. This means you’re likely to be putting unnecessary restrictions on your diet – and potentially putting you at a greater risk of nutrient deficiency. If you think that gluten may be the problem, the first step is to be tested for coeliac disease – and for results to be useful, you still need to be consuming gluten. If you have symptoms of IBS, discuss investigating coeliac disease first with a health professional before excluding gluten from your diet.

Gluten-free and wheat-free diets

Mistake: Skipping the wholegrains

My own PhD research looked at the nutritional adequacy of a gluten-free diet and it has been the only comprehensive study of the gluten-free diet in Australia. Similar to findings overseas, people following a gluten-free diet in Australia have a high likelihood of not eating enough fibre. People following a wheat-free diet may not have as great a risk, as they can still include rye and oats on their menu (both of which are good fibre sources). However, it’s important to choose higher fibre, wholegrain variations of foods including cereals, breads and pasta, where available.

Diets for weight loss

Mistake: Cutting back on nutrients, not just kilojoules/calories

Weight loss diets generally mean eating less food – and less food may mean insufficient nutrients. Unfortunately, many people concentrate solely on their kilojoule intake, and it’s important to make sure you’re giving your body vitamins and minerals, not just the right amount of kilojoules. For this reason, it is important that the foods you do eat are nutrient dense – in other words, they offer maximum nutrients for the amount of kilojoules they contain. If you’re trying to lose weight, aim to include lots of fruit and vegetables in your day – they’re nutrient dense, but relatively low in kilojoules. It’s also a good idea to consult with a dietitian to ensure you are consuming all of the vitamins and minerals you need.

Mistake: Thinking ‘low-fat’ means ‘weight loss’

Marshmallows, jelly beans, yoghurt and rice crackers are just some of foods claiming ‘99% fat free’ or ‘less than 5% fat’ on the packet. And that’s true, they are. However, that doesn’t necessarily mean they’re going to help with weight loss. Despite containing only a small amount of fat, these foods still contain kilojoules – and consuming too many kilojoules is a major cause of weight gain. You’re better off watching your portion sizes of all foods, low-fat or not.

Nut allergy

Mistake: Leaving yourself with limited nut-free alternatives

For many people with a nut allergy, an extremely strict avoidance of all traces of nuts is required. Obvious foods, such as peanut butter and satay sauce, need to be avoided, however, an increasing number of foods state ‘may contain traces of nuts’ on the packet. People with nut allergies may choose not to eat foods that have this warning and, as a consequence, will have less foods available to them. Less availability can compromise your ability to achieve a nutritionally adequate and balanced diet. Ensure you are still meeting the healthy eating guidelines when you choose foods that are free from the risk of nut contamination.

Egg allergy

Mistake: Missing out on treats and baked goods

Eggs are widely used in our food supply. For those with an egg allergy, it’s not just omelettes, frittatas and quiche that are off the menu – many baked ‘treat’ foods, such as cake, muffins and biscuits, often are, too. Missing out on these can lead to feelings of deprivation – which studies show can lead to overindulgence later on. If you love baked goods, try an egg replacer product – just remember to watch your portion sizes. You’ll find egg replacer products in the health food aisle at your local supermarket.



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