Does a varied diet help?
Even when calorie and protein intake is adequate, micronutrient deficiency can occur if your range of foods is too narrow. Where calorie intake is close to the minimum for bodily maintenance there is a long-recognised problem of inadequate micronutrient intake. Such deficiencies ought to be unlikely in the affluent world for people who consume a varied diet of vegetables, fruit, meat and fish. Indeed, many people live for eight or nine decades with no obvious nutritional problems. Even so, in surveys of food consumed, nutritionists find surprising numbers of individuals with deficiencies of Omega-3 fatty acids, magnesium, potassium, calcium, vitamins C, D, E and K. One explanation is the relatively new problem of food that is energy-dense (ie rich in carbohydrates and fats) and micronutrient-poor. Another is the penchant of some people for too narrow a range of foods. At a cellular level the consequences of micronutrient deficiency are likely to be deterioration of mitochondria, increased oxidative stress and damage to DNA. Together they are risk factors for compromised immunity, cancer and premature onset of age-related diseases.
The mammalian body seems to respond to even moderate scarcity of micronutrients by triaging the allocation of micronutrients to activities that are vital to early development at the expense of longevity. The micronutrients recruited by these processes are obtained to the disadvantage of less critical functions. At the sub-cellular level, this means energy generation is favoured over DNA-repair. At the cellular and organ level, blood cells that transport oxygen are favoured over cells involved in immunity and the heart is favoured over the somewhat less critical liver. This means the genomes of relatively young people exposed to moderate micronutrient deficiencies will register such deficiencies with no immediate symptoms but with insidious long-term consequences. Indeed deficiencies of thirteen micronutrients are known to damage the genome (see below). A different kind of damage caused by micronutrient deficiencies (zinc, iron, vitamin B6 and B7) affects the rate of assembly of important elements of the energy generating machinery of the cell (the mitochondrion).
All but one micronutrient are obtained solely through food but there is one exception of enormous importance. This is vitamin D which is now known to underpin many aspects of cell physiology.
Deficiencies of micronutrients in pregnant women have great importance for the development of the foetus – as it is dependent on the supply of nutrients from the mother – but also have far-reaching significance for health and longevity after birth.