For the past 20 years, Serge Rezzi has been putting foods under the microscope to see how they impact our health. He explains why we need a range of micronutrients in our diet – and why our wider approach to nutrition needs a radical rethink.
Between the 16th and 19th centuries, scurvy killed more than two million sailors. Navy surgeon Usher Parsons described the symptoms of this disease, which struck down whole ship crews. First, it caused ‘ulcers at the nose and mouth’, later ‘all the evacuations from the body become intolerably fetid’, and finally, ‘death closes the scene’. And all because the sailors were deficient in vitamin C – they couldn’t access fresh fruit and vegetables during long voyages.
Since then, we’ve learnt much more about micronutrients. They are vitamins and trace elements that are vital for our bodies to function well. As well as vitamin C, they include a host of other vitamins – from B group vitamins to vitamins A, D, K and E – and mineral elements that are just as vital for human biology, like iron, zinc, magnesium, manganese and copper. Unlike macronutrients – proteins, fats and carbohydrates – micronutrients don’t serve as direct energy sources, and we need them only in relatively small quantities. But they’re no less essential to keep our biological processes running smoothly.
A single vitamin wears many hats
We tend to associate vitamins with a specific function: vitamin E is an important antioxidant, vitamin K is key for blood coagulation and vitamin A is important for our vision, immune system and cell division.
But this belies a more complex reality. Vitamins are pleiotropic agents, meaning they work at many levels of our biochemistry and biology. We cannot reduce a vitamin to having a single health benefit. Micronutrients are part of complex networks and biochemical reactions, so it makes sense that when they are missing, our bodies stop functioning as they should. Over long periods, deficiencies may contribute to the development of complex diseases or their comorbidities. Modern diseases are multifactorial – meaning they have several causes – so we can’t pinpoint a single vitamin deficiency as the culprit but, in the long run, it’s clear that micronutrient gaps can have a huge impact on our health.
In light of this, the solution seems simple. We need to eat a balanced and varied diet to get enough of each micronutrient. Except, nutrition is never simple. Our lifestyles mean we often choose convenient food, rather than what is good for us – and for our cells. Many people assume that as long as they feel full and satisfied, their bodies are getting what they need. This is absolutely not the case.
Take obesity: it’s a misconception that obese people will not have any deficiencies because they’re ingesting enough calories. In truth, they are often deficient in micronutrients –commonly vitamin D or zinc, for instance – as obesity affects the way people absorb and metabolise micronutrients.