"Is sweet potato really healthier?" 7 super common nutrition myths busted by a dietician.

With the abundance of nutrition information available online, it’s easy to get confused. Everyone eats, which means everyone has an opinion about nutrition.

Unfortunately, many of those opinions are not scientifically correct. From hearing carbs are bad, to hearing fat is bad, to hearing fat is now good, to hearing eating gluten is basically a cardinal sin.

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Navigating the nutrition landscape can be a real headache. So, I’ve collated some of the most common nutrition myths I get asked about as a dietician below, and have broken down whether there is any real merit to them.

1. Is it gluten causing your gut grief or wheat fructans?

Gluten often bears the blame for causing gut symptoms such as bloating and abdominal pain. If your gut symptoms are because of coeliac disease, then gluten is certainly to blame. If coeliac disease has been ruled out, yet you find products like bread, pasta and cereal cause your gut grief, then wheat fructans are more likely at fault.

Wheat fructans are a type of fermentable carbohydrate (unlike gluten, which is a protein) which are poorly absorbed, particularly for individuals with sensitive stomachs. If wheat fructans are the issue, then you can enjoy a variety of gluten-containing products that are low in wheat fructans, such as traditional sourdough bread and rolled oats. It’s important to note that non-coeliac gluten sensitivity exists, but a wheat fructan sensitivity is more common.

2. Does chocolate cause acne?

As a die-hard chocolate lover, it hurts my soul to see it blamed for causing acne. But there may unfortunately be some merit to this one. Now, there is currently no clear evidence whether chocolate worsens acne. However, some of the research on nutrition and acne may support this theory.

Foods which have a high glycemic load (glycemic load is the amount of carbohydrate in a certain food), have a high saturated fat content and contain dairy have all been associated with worse acne in some individuals. So given that chocolate has a high glycemic load, contains dairy (except for some dark chocolate), and is high in saturated fat – it may have a role in exacerbating acne for some. If you enjoy chocolate (you’re only human) then stick to enjoying it occasionally in moderate amounts.

3. Do I really need 8 glasses of water a day?

The old 8 glasses of water (or 2 litres a day) gets thrown around as a blanket water recommendation, but is it accurate?

Water requirements are highly individualised and will change day-to-day depending on the level of physical activity, sweat and climate. Using 2-3 litres (8-12 glasses) of fluid per day is a good rule of thumb. If you exercise or sweat more, you will naturally need to drink more. Use the colour of your urine as a guide – it will be a pale straw to clear colour when well-hydrated. 

Keep in mind this is fluid requirements, not just water. So other fluids such as tea, coffee and milk all count toward your fluid target, but water should be the main drink of choice.

4. Do I need to avoid carbs at night?

If I had a dollar for every time I've been asked this question, I’d be able to buy a lot of gourmet sourdough that I could enjoy at night, because the answer is no. 

Carbohydrates don’t magically convert to fat or lead to weight gain when consumed after 5pm. For most of us, enjoying a serve of carbohydrate with dinner is actually beneficial, as it has been shown to help with sleep. For those who exercise in the morning, carbs the night before are also useful. You may notice a slight increase on the scale after a higher carbohydrate meal, but this is because of fluid retention, not true weight gain.

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5. Does dairy cause acne?

As mentioned earlier, research shows dairy seems to exacerbate acne in some individuals. This is thought to be because of the whey protein itself, rather than the saturated fat or lactose content. 

If you find dairy worsens your acne, seek support from an accredited practising dietician to assist with this, as it’s important to trial an elimination correctly.

6. Can food ‘boost’ our immunity?

Nutrition can absolutely help with supporting our immune system, but it cannot ‘boost’ it per se. So if someone is trying to market a pill or potion that promises an immune boost, run.

One of the best things we can do for our immune system to function optimally is eating enough. If we’re under fuelling, there isn’t enough energy available for our immune system to function optimally. Ensuring adequate levels of key nutrients such as vitamin D, zinc, and iron is also important for a healthy immune system. Including a variety of plant-rich foods to support a healthy gut and boost antioxidant intake is also important. 

7. Is sweet potato healthier than white potato?

Sweet potato often gets put on a pedestal for being the ‘healthy’ potato, largely because of its lower Glycemic Index (GI). The GI is a measure of how quickly our body breaks down carbohydrate and how quickly it spikes our blood sugar levels. 

Sweet potato and white potato are both nutritious options. They contain different micronutrients and both are a good source of fibre. Whilst most varieties of white potato do have a higher GI than sweet potato, they’re usually consumed with either protein or fat, which lowers the overall GI of the meal. You can also lower the GI of white potato by leaving the skin on. White potato lovers rejoice!

As many of these are complex topics, it is important to seek individualised advice from an accredited practising dietician to work out the approach that's best for you.

Amanda Smith is an accredited practising dietician and a certified fertility dietician at Verde Nutrition Co. You can follow her on Instagram here.

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