NutraIngredients speaks to nutritionist to find out what deficiencies people are risking when following on-trend diets, and what they must do to stay healthy.

Trendy diets lead to dangerous disorders, warns nutritionist

By Nikki Cutler

- Last updated on GMT

iStock / scyther5
iStock / scyther5
Trendy diets touted on social media are leading people to have serious nutritional deficiencies and irreversible illnesses, a nutritionist has warned.

Dr Laura Wyness, a registered independent nutritionist, says that many people are in danger of eating disorders as they copy diets they’ve seen online and wind up with serious deficiencies.

“It seems to be in human nature to take health advice to the extreme,”​ she told NutraIngredients.  “When people start putting strict rules and regulations on themselves and cutting out all one or several food groups – whether it be meat, fish, dairy, grains - the diets become dangerous.

 “Diets like this create an obsession with what you’re eating, which is how eating disorders often begin.”


“I am seeing more people coming to me with iron deficiencies. Many of these are young women who have stopped eating meat.”

Symptoms of iron deficiency include low energy, breathlessness and even heart palpitations. In order to increase Iron intake through a vegan diet, Wyness says it’s important to eat dark green leafy vegetables, beans, peas, lentils, seeds, nuts and dried fruit. But she also points out that eating one portion of these alone won’t make up for a portion of meat.

“Our bodies only absorb about 15% of the iron in vegetables, whereas it absorbs about 40% of the iron in meat.  So it’s important to make sure your body can absorb as much of the nutrients as possible.

“The tannins found in many teas can hinder nutrient absorption in our bodies so anyone avoiding meat should avoid these drinks within 30 minutes or eating their iron-filled foods.”


Wyness adds that a more worrying deficiency is calcium, which comes when people give up dairy.

This is a worrying one as it’s one that won’t show until older age. It’s really important to get enough calcium in your twenties and early thirties as this is essentially when your body is most able to build strong bones. If you don’t get the calcium you need during this age bracket you could find you suffer bone related problems when you get older, such as osteoporosis and arthritis.

 “Worryingly, generally it’s those aged in their twenties and thirties that seem to follow these trending diets.”

Vegan sources of calcium include green leafy veg like kale, broccoli and watercress, and dried fruits, wholegrains and pulses.


Dairy is also the main provider of iodine and if you do not have enough iodine in your body, you cannot make enough thyroid hormone. Symptoms of iodine deficiency include feeling cold when other people do not, constipation, fatique, muscle weakness, joint or muscle pain, depression, and dry skin.

“With so many people cutting out dairy, a lot of people are becoming deficient in this also. This – unlike calcium - is something many of the dairy-free milks aren’t fortified with.”


“The only dietary sources of B12 are mostly meat and dairy. They can get some from yeast extract like Marmite and they will also be able to find some fortified cereals and dairy milk alternatives but these aren’t likely to be enough. Therefore I would suggest vegans should take B12 supplements.” 

The symptoms associated with a B12 deficiency are similar to those associated with an Iron deficiency: feeling fatigue, shortness of breath, a sore tongue, mouth ulcers, pins and needles, and pale skin.


When it comes to Zinc, there’s a few plant sources – such as wholegrains and beans - but, again, there are certain extra advisories to consuming these as our body’s absorption of the nutrient is not as good as it would be from meat. The reason for this is that the phytates in the foods can bind to certain dietary minerals including iron, zinc, and manganese and calcium, and slow their absorption.

Wyness explains: “People should eat chickpeas, lentils, tofu, pumpkin seeds, cashew nuts, walnuts, chia seeds and quinoa. Soaking them before cooking them will help to remove the phytates and increase the nutrients absorbed.”


Traditionally, the best source of long chain Omega-3 is oily fish and there isn’t any other source as good as this.

“Omega 3 is needed for our heart, cognitive and eye health.​ You can get Omega-3 from flax seeds, chia seeds, walnuts, hemp seeds and rapeseed oil but they won’t provide the Long-Chain Omega 3 that oily fish provides. Although our bodies can convert the fatty acid into Long-Chain the body isn’t that good at doing this.

“The issue most people have is that our Omega-3 and Omega-6 balance is out and this is dangerous to our health.”

For most people, the ideal balance of Omega-6 to Omega-3 is a ratio of 4:1. Scientists believe Omega-6s are pro-inflammatory, while Omega-3s are anti-inflammatory. Inflammation is essential for your survival. It helps protect your body from infection and injury, but it can also cause severe damage and contribute to disease when excessive.

Wyness points out that it’s actually very hard for a person to tell if they are Omega-3 deficient but she suggests people not eating oily fish should ensure to keep this nutrient topped up by taking a supplement. Vegans can take algae oil supplements to avoid the use of fish.


Another on-trend diet is the gluten-free diet, which tends to see people cutting out bread, pasta, cereals and other carbohydrates, which have got a bad rep in recent years. However she points out that many of the gluten free creations are less healthy.

Many people are choosing to go gluten free even though they aren’t coeliac, just because they think it’s healthier, but these people are risking becoming fibre deficient which has a major impact on our health. A gluten free diet has been linked to a reduction in beneficial gut bacteria so ensuring you have adequate fibre is key. Fibre also helps to keep us full and therefore people who eat plenty of fibre, tend to eat less fat.

 “However, there are a variety of gluten free fibre options such as fruit, vegetables, beans, legumes, and gluten free grain such as buckwheat, quinoa and millet.

“Gluten free foods are sometimes higher in sugars or fats as these are often added to compensate for the lack of gluten to ensure the product retains a good texture and mouthfeel.”

Wyness adds that gluten free diets have also been found to be lower in calcium, iron, folate, thiamine, niacin and B12. 

The flexitarian or Mediterranean diet

Although her ideal advice would simply be “everything in moderation”, ​Wyness says the most healthy on-trend diets out there are the flexitarian or Mediterranean diets, which allow all the food groups to be enjoyed in a balanced manner.


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