Tired and putting on weight? This could be the surprising reason

Bad news for oat milk lovers: Swapping cow’s milk for vegan alternatives risks a deficiency of an essential mineral that can cause tiredness, weight gain and – in children – low intelligence. A study has found that if people replace half the dairy products in their diet with vegan substitutes, it would cut their iodine intake by up to 28 per cent. Iodine is needed to make the thyroid hormone, lack of which causes tiredness and weight gain. Risks are especially high in children, teenagers and pregnant and breastfeeding women, who need more iodine to support their brain development or that of their baby. Shorts “Strictly cutting out [dairy] is extreme. Even reducing it is a risk,” said Dr Ty Beal, a food researcher at the Swiss Global Alliance for Improved Nutrition, who was not involved with the study. “When you prioritise climate at the expense of health, I think it’s irresponsible.” Iodine consumption can vary depending on where you live, as the main repository of iodine is seawater. The mineral is found in seafood and is present in rainwater in coastal areas. Historically, some villages in Alpine valleys with poor soils had such low iodine intake that they were known for the number of people with low thyroid function and low IQ. The original meaning of the word “cretin” was someone born with learning difficulties due to lack of iodine, although it is now considered offensive. The switch to plant-based milks Such severe deficiency is now rare, because many countries add iodine to table salt. The UK does not, because Britons have traditionally eaten a lot of dairy produce, a good source of iodine because it is added to cattle feed. Today, however, people are increasingly drinking plant-based milks for health, climate, or ethical reasons. The NHS says dairy products such as cheese and butter are high in saturated fat, which is bad for the heart. It advises people to buy low-fat milk or use plant substitutes as “good alternatives to dairy products”. Oat milk tends to be most popular. The UK Climate Change Committee, which advises the Government, has net zero goals of a one-fifth cut in meat and dairy consumption by 2030, and a one-third drop by 2050. Getting enough iodine is vital in pregnancy (Photo: Getty) But plant-based substitutes tend to be lower in vitamins and minerals normally supplied by dairy products, said Dr Sarah Bath, associate professor at the University of Surrey, who led the research. As well as iodine, these include calcium, and vitamins B2 and B12 – but iodine is the biggest concern, as only one in 10 plant-based products are fortified with it. ‘UK is particularly vulnerable’ To find out how recommended dietary changes would affect people’s health, Bath’s team combined UK eating habits from the last National Diet and Nutrition Survey with manufacturers’ nutritional information on their products. They published their findings in The Lancet Planetary Health. The analysis found that at the moment, most people are getting enough iodine, apart from teenage girls, half of whom are going short. But that would change if more people switched to dairy-free options. If teens replaced half of their dairy with plant products, 80 per cent of girls and 72 per cent of boys would be deficient. If adults under 50 replace all of their dairy with plant products, 64 per cent of women would be deficient in iodine, while 41 per cent of men would be, researchers found. “This is something that needs to be taken into account if diets change, not to forget about these micronutrients that are found in milk and dairy products,” said Bath. “The UK is particularly vulnerable to iodine insufficiency due to a lack of a fortification policy such as universal salt iodisation. “People are unaware that dairy products are a major source of iodine, and that plant-based alternatives, unless fortified, have a very low iodine content.” Other ways to get iodine Emily Angus, senior dietitian at The Vegan Society, said: “The Vegan Society has always recommended that people choose fortified dairy alternatives. The majority of plant-based milk alternatives available to UK consumers are fortified with calcium and vitamin D as a minimum.” Bath’s team also calculated that iodine deficiency could be avoided, even if everyone switched to vegan products, if there was standardised iodine fortification of dairy substitutes, and of bread. If people are having non-fortified dairy substitutes, other ways to get enough iodine include taking supplements or seeking out iodised salt to add to their cooking, said Beal. Seafood and seaweed are other good sources. It is also crucial to shake a carton of plant milk well before using – otherwise many of the nutrients sink to the bottom of the carton, he added.