3.5 Describe the factors that influence how much of each nutrient a person needs

This guide will help you answer 3.5 Describe the factors that influence how much of each nutrient a person needs.

Every person needs a range of nutrients to support growth, health, and daily activities. Nutrients include protein, carbohydrates, fats, vitamins, minerals, and water. The quantity of each nutrient a person needs depends on several factors. Your body and life circumstances shape what your body requires each day. These requirements can change over time.

Age

A person’s age has a strong effect on nutrient requirements. Our bodies change as we grow, and so do our needs.

• Infants and young children: Growing bodies need more calories, protein, calcium, vitamin D, and iron for bone, brain, and tissue development. Babies, for instance, get their nutrients mainly from milk, which meets most of their early requirements.
• Adolescents: Teenagers are going through rapid growth spurts. They often need more energy, protein, iron (especially girls starting menstruation), and calcium.
• Adults: Once growth stops, energy needs may reduce. Adults need nutrients to maintain cells and organs, fight off infection, and repair damage.
• Older adults: With advancing age, muscle mass can decrease and the body’s processes slow down. Energy needs often drop, but requirements for nutrients like vitamin D, calcium, and vitamin B12 can increase. Bones and immune system need particular support.

Age is a basic starting point for setting nutrient levels. Recommended intakes vary across life stages to support these changes.

Sex

Biological sex (male or female) affects nutritional requirements.

• Men tend to have more muscle mass. This means a higher energy and protein requirement, particularly for those who are active.
• Women of childbearing age need more iron due to menstrual blood loss. They might also need more folic acid if planning to become pregnant, to reduce the risk of birth defects.
• After menopause, women’s iron needs drop, but calcium and vitamin D become especially important for bone health.

Each official guideline for nutrients gives different values for men and women, reflecting these differences in physiology and needs.

Body Size and Composition

Your size and body composition (how much muscle and fat you have) have direct effects on your nutrient needs.

• Tall or heavy people usually require more energy each day than smaller people.
• Muscle tissue uses more energy than fat tissue. People with more muscle may need more protein and energy.
• Overweight individuals may need to control energy intake for weight management, while still meeting all vitamin and mineral requirements.

Assessing weight, height, and body type helps determine appropriate portion sizes and nutrient intake.

Level and Type of Physical Activity

The amount of physical activity you do changes your nutritional needs. Physical activity includes work, exercise, and everyday movement.

• Very active people burn more calories and so need more energy from food. They must also replace nutrients lost during activity, such as sodium and potassium lost in sweat.
• Athletes and regular exercisers need more carbohydrates for energy, more protein to repair muscle, and sometimes more vitamins and minerals to support recovery.
• Low activity levels mean fewer calories are needed to prevent weight gain, but needs for essential vitamins and minerals remain steady.

Work out your energy needs based on how active you are each day.

Health Status and Medical Conditions

Past and present health conditions play a big role in shaping nutrient needs.

• Infection or injury: Healing from illness or surgery increases demand for protein, energy, and certain micronutrients.
• Chronic illnesses: Conditions like diabetes, kidney disease, heart disease, and digestive disorders may require changes in the types or amounts of certain nutrients.
• Food allergies or intolerances: Some people must avoid foods that would otherwise be good sources of key nutrients, such as dairy (for calcium) or gluten-containing grains (for fibre and some B vitamins).
• Pregnancy and breastfeeding: Needs for nearly all nutrients rise, but especially energy, protein, iron, folic acid, calcium, and vitamin D.

Healthcare professionals often recommend specialised diets or supplements in these cases.

Pregnancy and Lactation

During pregnancy and breast-feeding, a woman’s body is not just supporting her, but a growing baby.

• Energy: Higher intake is needed, though not “eating for two” as the saying goes.
• Protein: Needed for the growth of foetus, placenta, and the tissues supporting pregnancy.
• Vitamins and minerals: Folic acid is especially important in the first trimester to support nervous system development. Iron is needed to make extra blood. Calcium and vitamin D support the baby’s bones.
• Breastfeeding: Producing breast milk takes energy and nutrients from the mother’s body, so extra intake is needed.

Care plans for pregnant and breast-feeding mothers often include supplements when dietary intake may not cover these increased demands.

Genetics

Genes influence how we absorb, use, and process nutrients. People inherit differences in metabolism, digestion, and even taste preferences.

• Some people process fats, sugars, or caffeine more slowly or quickly than others.
• Vitamin and mineral absorption: Variations in genes can affect how well someone absorbs nutrients such as iron or vitamin D.

While healthcare and nutrition guidelines cover most people, some may have unique needs based on their inherited traits.

Environmental Factors

Where you live and your living conditions can change what you need and what you can get.

• Climate: More water and electrolytes are needed in very hot weather, as you lose more fluids through sweat.
• Altitude: At high altitude, energy needs may go up and more iron may be needed because of changes to red blood cells.
• Air pollution and sun exposure: People with little sun exposure may need more vitamin D from their diet or supplements.

Your surroundings can make certain foods less available, which shapes what nutrients need extra focus in your diet.

Lifestyle and Habits

Personal choices affect nutrient requirements.

• Smoking smokers need more vitamin C to help counteract some of the damage caused by chemicals in tobacco.
• Alcohol use heavy drinking can interfere with the absorption and storage of several nutrients, especially B vitamins, vitamin A, and minerals.
• Vegetarian or vegan diets people who do not eat animal products need to find alternative sources of protein, iron, vitamin B12, calcium, and omega-3 fatty acids.

Food choices, habits, and personal preferences all influence which nutrients you might need more or less of.

Socioeconomic Status and Economic Access

Income and education often affect the types and amounts of foods people eat.

• Low income: May limit access to fresh fruit, vegetables, protein-rich foods, or supplements. This can lead to shortfalls in vitamins and minerals.
• Education: People with more knowledge of diet and health are sometimes better at making food choices to meet their nutrient needs.
• Food insecurity: Not having a steady or reliable access to enough food can cause undernutrition or imbalance.

Government support programmes and food banks play a part in reducing these gaps.

Cultural Influences and Beliefs

Beliefs, traditions, and cultural backgrounds can shape food choices and patterns.

• Religion: Some faiths have food rules, restrict certain foods, or encourage fasting at particular times of year.
• Customs: Family traditions may favour specific ingredients or types of dishes but can also limit exposure to nutrient-rich foods.
• Stigma or taboos: Certain foods might be avoided for social reasons, which can alter nutrient intake.

Nutrition professionals respect these beliefs and help find suitable, balanced options.

Life Stage and Growth

Different times in life mean different focus on growth and maintenance.

• Children and teenagers: Fast growth calls for higher nutrient intakes.
• Pregnant women: Rapid tissue growth and development.
• Older adults: Focus on preservation of muscle, bone, and cognitive function.

Setting nutrient intake by life stage prevents shortages or excesses.

Stress and Illness

Physical and mental stress both put demand on the body’s nutrient supply.

• Physical stress: Like surgery, burns, or illness, uses up protein and energy reserves more quickly.
• Mental stress: Can change appetite and impact how nutrients are absorbed and used.

Short-term or long-term illness can both shift what the body needs from the diet.

Use of Medications

Medicines can influence your nutrition by affecting appetite, digestion, or nutrient absorption.

• Some drugs lead to loss of nutrients through urine (for example, some high blood pressure tablets cause potassium loss).
• Others reduce nutrient absorption in the gut, especially antibiotics or drugs for stomach acid.
• Medical treatments like chemotherapy can cause a loss of appetite, nausea, or vomiting, all of which make it hard to get enough nutrients.

Always check if new medicines affect your nutrition.

Supplements and Fortified Foods

Eating patterns change when people take vitamin, mineral, or protein supplements.

• Supplements: May prevent deficiencies where the diet is not enough, but large doses can sometimes be harmful.
• Fortified foods: Many basics like bread, milk, or breakfast cereals have added vitamins and minerals to help people meet recommended intakes.

Supplements are often advised for certain groups, such as pregnant women (folic acid) or older adults (vitamin D).

Dietary Preferences and Trends

Food fashions and diet fads can lead people to restrict or emphasise certain foods or nutrients.

• Low-carb or low-fat diets: These may mean higher or lower intakes of certain nutrients.
• Allergy-free branding: Popular but sometimes misses out on vital nutrients.
• Meal skipping or fasting: Alters the way nutrients are supplied and used.

Awareness of new trends helps individuals meet their needs and spot gaps.

Food Availability and Seasonality

The types of foods available in the shops can vary by season, region, and access.

• Seasonal changes: Fresh fruit and vegetables may be easier to get at certain times.
• Supply chain issues can affect the reliability and price of specific foods.
• Urban versus rural: Rural residents may grow more of their own food, while urban dwellers depend more on supermarkets.

Being flexible with food choices helps cover nutrient bases over the course of the year.

Hydration and Fluid Needs

Water is essential for survival, but needs change each day.

• Climate: Hot weather, heavy exercise, fever, or illness all increase fluid loss and demand.
• Diet: High-protein or high-fibre diets require more water.
• Age: The elderly may not feel thirsty and so can miss signals to drink, raising risk of dehydration.

Keep track of how much you drink and increase intake when active or unwell.

Interaction between Nutrients

Some nutrients affect how well others are absorbed or used in the body.

• Calcium and iron: Taken together, they can block each other’s absorption.
• Vitamin C and iron: Vitamin C helps the body take up iron from plant foods.

Balance is important, and both excesses and deficiencies of one nutrient can affect another.

Final Thoughts

Meeting the right level of each nutrient each day is a moving target. The amount you need depends on much more than a single factor. Your age, sex, activity level, health, and situation all change what and how much your body needs. Life events such as pregnancy, illness, or stress also bring new demands.

Pay attention to changes in health, habits, and circumstances. Checking food labels, using balanced meal plans, and following trustworthy information makes a difference. Sometimes, a healthcare professional or dietitian can offer guidance tailored to personal requirements.

Remember, no single factor works on its own. Nutrition is about piecing together your individual needs with your personal circumstances. Supporting good health is a long-term commitment, not a one-off action. Regular review and adjustment helps you get the right nutrients, keep well, and feel your best every day.