22/05/2014 10:53 BST | Updated 22/07/2014 06:59 BST

How Our Immune System Changes Through Life

Our immune system through the ages. At birth, a baby's immunity relies upon antibodies and gut flora passed from their mothers. Over time the new baby builds up his or her own immune system through a combination of exposure to the environment, mother's milk and eventually the vitamin, minerals and other nutrients in weaning foods. In other words, from the moment of birth, immunity is an evolving thing - and it changes not only during the first months and years of life, but over a lifetime, making us more or less susceptible to certain illnesses at different stages in our lives.

We also know that, as we age, we become less responsive to vaccination against disease and that the most effective ways to help our immune response are through the use of diet, nutrition and other principles of healthy living, such as exercise and stress relief. In other words, while immunization becomes less effective over the course of our lives, natural approaches to improved immunity can provide a lifetime's protection

Examples of changing needs of the immune system and its response with age:

• In childhood the body is building up its immunity "memory" - children get lots of colds because the body hasn't yet been programmed to recognize strains of infection and attack them. We don't want to prevent this important process, but we do want to be able to fortify our children to overcome simple infections and speed recovery.

• The balance of friendly bacteria in the gut changes with age. During childhood we have more bifidus strains of good bacteria, whereas during adulthood the balance tips in favour of lactobacillus strains. In order to achieve optimum immune response in the gastrointestinal tract, a balance of good bacteria - which can be achieved through diet - is essential throughout life. Studies show that the balance of good bacteria in the gut is important not just for fighting stomach upsets, but also for preventing allergies, intolerances and even IBS, as we move from childhood to adulthood.

• The rapid decline of the thymus gland, which produces the T cells that form the front line of the immune system, by middle age, means that the need for an immunity boost is significantly greater at 40 than it was at 14 - and even greater still at 64.

• During old age one of the body's most important barriers to infection, the skin, becomes thinner, drier and weaker making it more likely that pathogens can enter the body's tissues. Keeping the skin strong and supple well into old age using nutritional changes, such as reducing sugar intake and boosting strengtheners such as vitamin A precursor, beta-carotene can support the immune system in our senior years.

• A growing number of studies show that people aged 65 and older are "macronutrient deficient", because older people tend to eat less frequently and a less varied diet. This, in turn, hampers their immune response. Although appetite can be smaller later in life, simple, light meals can still be nutrient rich.

By looking at the immune system age by age, considering the physiological changes and evolving nutritional needs of the human body so that the reader can tailor diet not only to support immunity at different stages of life, but also to tackle certain age-related illnesses and to optimize, at the earliest possible opportunity, protection against diseases that we may be more prone during the next phase of our lives.