But the risks of inadvertently malnourishing a child aren't restricted to veganism. According to Claire Williamson of the British Nutrition Foundation, one of the mistakes parents can make is to assume, wrongly, that what's healthy for an adult is healthy for a child. "For example, semi-skimmed milk, low-fat foods and high-fibre foods may be best for adults, but under-fives need full-fat dairy produce, while high-fibre roughage can fill them up too quickly, so they don't eat enough nutritious food