As our bodies grow and age, it is essential that the food we eat has all the nutrients we need to thrive, writes Lynne Caffrey. But who needs what, and when?
Public health experts have moved away from the blanket 'breast is best' message to reassure new mums that every breastfeed they can manage makes a difference to their newborn's development. Breast milk contains everything a baby needs until they begin to wean, usually between four and six months. However, all healthy, full-term infants should be given vitamin D3 until they are 12 months old. The recommended dose is five micrograms every day (5μg or 200IU).
Avoid giving gluten-containing cereals at this stage as these have been linked to the development of coeliac disease in later life. Sauces (such as gravy) and foods rich in salt should also be avoided, as babies' kidneys can't cope with much salt.
Children up to 5
This is a period of huge growth and development, where children should enjoy a range of foods from the main groups: fruit and vegetables, dairy, starchy foods, protein-packed foods and fats, oils and spreads. By age five, a child should be eating roughly half the amount an adult does.
Starchy foods such as bread, porridge, cereal, potatoes, pasta, rice, noodles and couscous power kids with energy, also helping their bodies use fat and protein to build muscle. In the case of fortified breakfast cereal, starchy foods can also provide extra vitamins and minerals. This is why starchy foods should make up the bulk of your child's diet, up to five servings a day by age 5.
Fruit and vegetables provide a huge range of vitamins and minerals as well as fibre; they should be the second-largest component of the diet, at up to five servings a day by age five. Calcium-rich foods such as milk, yogurt and cheese are vital to build strong bones. Semi-skimmed milk should only be introduced after age two if your child has a varied diet.
Protein-packed foods - meat, fish, eggs, nuts, beans, lentils and tofu - also support bone growth and development, and are a source of iron. Children should get two servings a day. Turkey burgers, hummus and healthy peanut butter are all fun sources of protein that kids will eat.
Oily fish (salmon, herring, mackerel, trout and sardines) and eggs are great sources of the 'sunshine' vitamin D and omega 3. Getting oily fish into children's diets once or twice a week has been shown to enhance verbal skills, brain development and vision. Avoid whole nuts, due to the choking hazard, and nut butters high in sugar. Limit processed chicken nuggets, sausages, fish fingers and burgers, as these are high in fat and lower in protein.
New Healthy Eating Guidelines for children aged one to five years are being developed by Healthy Ireland to help support parents and carers.
At this age our nutritional needs stabilise - with a few tweaks here and there. Dietitian Sarah Keogh, from Eatwell in Dublin, says that "from five to 105, you're going to need more or less the same amount of nutrients.
"For children and teenagers, iron is a big one; 52pc of girls aged between nine and 12 and 75pc of teenagers don't get enough iron," she adds. Iron deficiency can make children tired, irritable and more prone to infection. Unless a child has been tested for anaemia, Sarah doesn't recommend giving them an iron supplement; instead, iron-rich foods are key. Iron from red meat, chicken and fish is most easily absorbed by the body and should be accompanied by a food or drink rich in vitamin C to help absorption. Sarah also recommends spinach and kale, pumpkin seeds, almonds and eggs.
Smoothies and fruit juices are a tempting way to increase vitamin C and fibre but they should be given sparingly, as juicing depletes the nutritional content of fruit and vegetables and releases sugars. One small glass (150ml) of 100pc pure, unsweetened fruit juice can count towards one of your five-a-day. More than one glass still only counts as one serving.
Iron and calcium are key at this age. Girls' requirement for iron rises as they begin menstruating, while calcium is important to lay down strong bones for life, which is done by age 19. Sarah says she's increasingly seeing teens who shun dairy sources of calcium for green vegetables.
"I've met a lot of teenagers in recent years who've read something about dairy on social media and go off dairy. One girl thought eating a sprig of broccoli each day would meet her calcium needs and I had to explain she'd need 16 servings of broccoli each day."
There's evidence that magnesium can help increase bone density in teens during this pivotal age. A diet rich in legumes (chickpeas, lentils, beans), nuts, seeds, wholegrains and green leafy vegetables (such as spinach), fortified breakfast cereal and milk and yogurt should meet magnesium needs.
At this age, portion sizes increase with energy needs, meaning boys need up to seven servings of starchy foods (the same as an adult man) and five servings of milk, yogurt and cheese.
Adults aged 20-65
As people make decisions about their own nutrition, misinformation and fad diets can lead to them cutting out useful nutrients, something that Sarah sees frequently in her clinics.
"We've seen the calcium intake falling off in people into their 20s and 30s. A lot of it is to do with the misinformation that is around dairy: they're under the impression they're getting calcium from green veg." Sarah says these sources aren't rich enough to meet the body's needs, favouring a life-long diet featuring milk and yogurt.
Sarah also recommends a diet rich in oily fish, especially for women at this age. "Some evidence suggests the benefits of fish oil are seen before you're even born - which is why we encourage women to eat fish during pregnancy and introduce fish when they're weaning their children."
It's recommended that women heading into menopause, when hormonal changes can disrupt the bone-building process, maintain their calcium and vitamin D intake, and take up a weight-bearing exercise. But there is another concern:
"After the age of 50, a woman's oestrogen levels have reduced; because of this, she is more at risk of heart disease, which is the biggest killer in Ireland," says Orla Walsh, a dietitian with a private practice based in Dublin. "Every diet at the age of 50 should be tailored to improving heart health. For example, they may need to increase their nut and seed intake, or to increase oily fish."
We vary hugely in terms of health, mobility and independence at this age, but there are some common factors: "You need more protein in your 70s than in your 20s, so it's important to make sure it is eaten at every meal," Sarah says. "Protein stimulates muscle repair, development and growth, so when you eat protein more often throughout the day, and do a little bit of exercise, the two trigger muscle-building."
A diet rich in fibre can also beat constipation, which can develop as activity slows. Changing the diet to include 100pc wholemeal or wholegrain bread, wheat biscuits, porridge, brown rice and pasta, more fruit and vegetables, linseed, prunes and pulses can also help ward off heart disease, stroke and some cancers.
Orla says, at this age, it's about balancing nutritional needs with mobility, medication and whether the person can feed themselves. "When someone is over 80, their activity level may have reduced due to mobility or illness, so a dietitian may reduce their carbohydrate requirements. Our protein requirements increase from the day we're born until the day we die, but if someone has a low appetite, it can be difficult to eat enough. My role as a dietitian in a nursing home, for example, would be to ensure the person has a diet adequate in protein but also in fibre. It's about finding that balance."
Are supplements really necessary?
Some people swear by a daily dose of vitamin C to get them through winter, while multivitamins are increasingly tailored to prevent everything from hair loss to ageing. Should we all be popping these pills or is it just money down the drain?
Dietitian Sarah Keogh recommends that everyone take additional vitamin D3 and omega 3 throughout their life. The RDA for vitamin D3 is five micrograms (µg) per day for those aged 5-50, rising to 10 micrograms per day for those aged 51 years and over.
When choosing an omega, look for one made from fish oil for maximum benefit. However, Sarah prefers that children get their fish oils from fish rather than supplements. "Fish doesn't just have omega 3: it has iodine, which is important for brain development, and B vitamins and minerals. The nutrition package you get from fish is so incredible that if you can get kids to eat it, that's the way to go."
Iron supplements should only be taken if you have been tested and found lacking, while a balanced diet offers the best source of vitamin C. "If you get your vitamin C from a supplement, there's a temptation to not eat foods rich in it, which means you miss out on fibre and antioxidants," Sarah says.
"Multivitamins can be useful to top up a healthy diet, certainly if they contain vitamin D, but if people are eating a diet including fish, nuts, seeds, fruit, vegetables and some oily fish, they shouldn't need one."
All sexually active women of child-bearing age should take 400 micrograms of folic acid, which produces and repairs DNA, to protect against neural tube defects such as spina bifida in babies. It is essential that there is enough stored in the body before conception to provide maximum protection, and that folic acid supplementation is continued up until the 12th week of pregnancy.