Swapping dairy products for plant-based alternatives like oat or almond milk could lead to significant nutrient deficiencies, particularly iodine, according to a study published in The Lancet Planetary Health journal. Researchers found that even moderate reductions in dairy consumption can decrease intake of essential micronutrients, with iodine showing the steepest decline.
Iodine is crucial for thyroid hormone production, which regulates metabolism and supports growth and brain development. Insufficient iodine can slow metabolism, potentially leading to weight gain, memory issues, and chronic fatigue. For pregnant women and developing children, even mild deficiency can have long-term cognitive consequences. The study indicates that around a third of women of childbearing age already have low iodine levels, and this risk increases with a shift to plant-based alternatives.
The research, conducted by experts from the University of Surrey and Queen's University Belfast, analyzed the dietary intake of 3,500 people. They examined the nutritional content of various plant-based milks, yogurts, and cheese alternatives. Their findings revealed that only 12% of these products were fortified with iodine, while calcium fortification was present in 61%, vitamin B12 in 46%, and riboflavin in just 20%.
When replacing 20% to 35% of dairy products with plant-based options, the proportion of teenage girls with inadequate iodine intake rose from over half to nearly two-thirds. For women of childbearing age, this figure increased from 32% to 42%. If all dairy were replaced, iodine deficiency rates could reach 80% among teenage girls and 72% among boys of the same age.
Experts noted that the UK is particularly vulnerable to iodine insufficiency due to the absence of a universal salt iodization policy, common in many other countries. Dairy products are a rich source of iodine in the UK, and many consumers are unaware of this. Plant-based alternatives typically contain very little iodine unless specifically fortified.
Calcium intake also poses a risk. The study found that if dairy products are removed from the diet, nearly half of teenage boys and 70% of teenage girls could become calcium deficient, increasing their risk of osteoporosis later in life. Riboflavin and vitamin B12 deficiencies are also concerns, impacting skin, eye, and nervous system health.
The researchers concluded that mandatory fortification of plant-based alternatives with essential nutrients could protect public health. They suggested fortifying bread with iodine as another cost-effective method to boost intake across the population. However, UK public health officials have been hesitant to implement salt fortification due to efforts to reduce salt consumption.
Signs of iodine deficiency can include fatigue, weight gain, dry skin, constipation, difficulty concentrating, and hair loss. While NHS guidelines suggest a varied diet including fish, eggs, and milk provides sufficient iodine, individuals avoiding animal products may need supplements. Some plant-based drinks are fortified, but organic alternatives cannot legally be fortified, and soy milk generally contains slightly more iodine than oat or almond milk unless fortification has been added to the latter.