Understanding nutritional requirements
Article by Rhiannon Lambert, BSc MSc RNutr
Why are nutritional requirements important?
Scientific research over the years has proven that humans need many different nutrients in order to maintain health and lower the risk of disease. The actual quantity of each nutrient is known as the nutritional requirement.
“Nutritional requirements vary between individuals based on a number of factors”
What are RNIs and DRVs?
In the UK, Reference Nutrient Intakes (RNIs) are used for protein, vitamins and minerals. These estimate the amount of each nutrient that is required to meet the needs of most of the group for which they apply.
The RNI of each nutrient is based on a number of factors. Each nutrient has a set of functions within the body, which means each is needed in different amounts. For example, protein is needed in much higher quantities compared to vitamin B12.
Further to this, nutrient requirements also vary between individuals as a result of age, sex, physical activity, state of health etc. For example, men require less iron compared to women of childbearing age.
To determine how much fats (total and saturated fats), carbohydrates (sugars and fibre), and salt we should be consuming in our diet we use Dietary Reference Values (DRVs). These have been set for the population and are represented as a percentage of total energy intake. For adults, it’s suggested that 50% of our energy each day comes from carbs, with no more than 5% of this coming from free sugars, and 30% coming from fats, with no more than 11% coming from saturates. For salt and fibre, recommended intakes for adults have been set as no more than 6g of salt each day and at least 30g of fibre each day.
Although, as humans, we eat foods and not single nutrients, our health is affected by the amount and the combination of these nutrients in the foods we choose to eat.
It is important to be aware of your reference intake on a daily basis as this will help you make the right dietary choices. To help support your dietary intake, here you can see how the NHS breaks down the Eatwell Guide that ensures you have a healthy and balanced diet.
How were these values calculated?
In the 1900s, using all the available scientific evidence based on health and disease, the Committee on Medical Aspects of Food and Nutrition Policy (COMA) gave advice on nutrient requirements for particular groups of the population.
Since then the Scientific Advisory Committee on Nutrition (SACN) has superseded COMA and has published updated advice on all those nutrients which are deemed a cause of concern (i.e. for those where deficiency is common or where deficiency can have serious effects).
Nutritional requirements
In terms of energy and what we need to sustain a healthy and happy lifestyle depends on a number of factors and will change throughout the lifespan.
For further information please visit the British Nutrition Foundation website where you can see a detailed breakdown for the different age groups and the specific nutrition requirements, for carbohydrates, protein, fats, fibre, vitamins, and minerals, for different age ranges. It’s important to remember that these values are based on averages for these populations and should be used as a guide. Everybody is unique and there are lots of factors that will influence how much energy we need each day.
What are the nutritional requirements for children?
Breastfed babies under 1 year (<12 months)
Males = ~530-700 kcals per day
Females = ~480-650 kcals per day
Formula fed babies under 1 year (<12 months)
Males = ~600-740 kcals per day
Females = ~550-670 kcals per day
Children aged 1 to 3 years
Males = ~765-1170 kcals per day
Females = ~~720-1070 kcals per day
Children aged 4 to 10 years
Males = ~1390-2030 kcals per day
Females = ~1290-1930 kcals per day
Children aged 11-18 years
Males = ~2130-3160kcals per day
Females = ~2030-2460 kcals per day
What are the nutritional requirements for adults?
Adults aged 19-64 years
Males = ~2770-2580 kcals per day
Females = ~2180-2080 kcals per day
Adults over 65 years
Males = ~2350 kcals per day
Females = ~1910 kcals per day
What are the nutritional requirements during pregnancy and when breastfeeding?
During pregnancy: Generally speaking you need about an extra 200 calories per day in the 3rd trimester
Breastfeeding: You will need to increase your daily energy intake by around 400-500 calories to help support your body during the breastfeeding period. You will also need to increase intakes of certain nutrients, including protein, omega-3, calcium, folate, choline, and iodine to help with milk production.
Iron, folate, selenium, & vitamin D requirements
SACN recommends that each day we consume:
Iron: 8.7mg men; 14.7mg women
Folate: 200µg (400µg supplement in the first 12 weeks of pregnancy)
Selenium: 55µg (60µg for pregnant women and 70µg for lactating women)
Vitamin D: 10µg
For more information see our Iron, Folate, Selenium, and Vitamin D factsheets.
Sugar, salt, & fat intake – how much should we be eating?
Salt
In the UK the Government recommends that we consume no more than 6g of salt each day – this is about 1 teaspoon. But, research has estimated that adults in England actually eat 8.4g of salt every day. Many people don’t realise that they are eating too much because it is ‘hidden’ in processed and prepared foods, sweet biscuits and baked goods, and even some vegetables when tinned in brine. To help reduce salt opt for low-salt/low-sodium food items or experiment with herbs and spices to flavour your favourite dishes.
Sugar
The NHS recommends that adults eat less than 30g of free sugars per day. Free sugar refers to any sugar that may be added to a food to give it a sweeter flavour. Foods that contain free sugars often have little to no nutritional benefit. This does not include naturally occurring sugars found in foods like fruits and dairy products. Tips to reduce the amount of free sugars that we have in our diets include swapping sugary sweetened drinks for water, have smaller portions of higher sugar foods, swap sugary foods like biscuits for oatcakes and add fruit to your breakfast cereals instead of sugar or syrups.
Fats
Lastly, fat is often demonised in the media however fat is a crucial part of our diets. It provides us with energy, delivers flavours to foods, and helps us to feel full and satisfied. The UK Government recommends that 35% of our total daily energy intake comes from fat, with only 10-11% (around 30g for men and 20g for women) coming from saturated fats, which have been linked to heart disease. The key public health messages that come with fat intake is to eat less foods that are high in saturated fats and replace it with healthier fats from fish and plants, like olive oil, salmon, and avocados.
Not all calories are equal
When we think about the nutrients and food that we consume, most people automatically think about the number of calories they are eating. A calorie is a unit of measurement used to estimate the energy content of the food we eat. More specifically it is the amount of energy it takes to raise the temperature of 1g of water by 1°c. However, not all calories are equal and your body may not absorb and gain the full amount of energy released from foods. In addition, two people may absorb different levels of nutrients from the quantity of the same food and our individual gut health and the length of our intestines play a role in how much energy we absorb from the food we eat.
Calories aren’t everything
It is important to remember that calories are not everything and numbers definitely do not dictate how healthy you are or the quality of your nutrition. You could be eating in the ideal range of calories for your body by eating chocolate brownies for breakfast, lunch, and dinner, however this will not provide your body the vitamins and minerals and fibre it needs to function optimally. Of course having a chocolate brownie is okay – moderation is key – this is where eating a balanced diet is really important as it makes sure that we get the nutrients we need whilst still enjoying the foods we love without restriction.
