RDA stands for Recommended Daily Allowance. Unless otherwise stated, all amounts shown are based on adults leading normal lifestyles.

Vitamin A/ retinol

• RDA is 0.7 mg for men, 0.6 mg for women.
• Good for eyesight, immune system.
• Food sources include liver, cheese, eggs, and oily fish.

Vitamin B6/ pyridoxine

• RDA is 1.4 mg for men, 1.2 mg for women.
• Good for turning food into energy, and making hemoglobin (the substance that carries oxygen round the body).
• Food sources include poultry, whole cereals (oatmeal, wheat germ), and peanuts.

Vitamin B12

• RDA is 0.0015 mg.
• Good for nervous system, making red blood cells, and turning food into energy.
• Food sources include meat, salmon, cheese, and eggs.

Vitamin C/ascorbic acid

• RDA is 40 mg.
• Good for healthy cells, and absorbing iron from food.
• Food sources include oranges, peppers, broccoli, and cabbage.

Vitamin D

• RDA is not set for those leading a normal lifestyle. For pregnant, or breastfeeding, women, or those confined indoors, RDA is 0.01 mg.
• Good for bones and teeth.
• Food sources include oily fish and eggs.

Calcium

• RDA is 700 mg.
• Good for bones and teeth, muscles, and blood.
• Food sources include milk, cheese, broccoli, and cabbage.

Folic acid/ folate

• RDA is 0.2 mg. For pregnant women, RDA is 0.4 mg.
• Good for making red blood cells and preventing birth defects.
• Food sources include broccoli, Brussels sprouts, peas, and brown rice.

Iron

• RDA is 8.7 mg for men, 14.8 mg for women.
• Good for making red blood cells.
• Food sources include meat, beans, whole grains, watercress, and curly kale.

Magnesium

• RDA is 300 mg for men, 270 mg for women.
• Good for bones and turning food into energy.
• Food sources include spinach, nuts, and bread.

Niacin/ vitamin B3

• RDA is 17 mg for men, 13 mg for women.
• Good for nervous system, the digestive system, and turning food into energy.
• Food sources include beef, pork, eggs, and milk.

Potassium

• RDA is 3500 mg.
• Good for lowering blood pressure and balancing fluids in the body.
• Food sources include bananas, vegetables, nuts and seeds.

Riboflavin/ vitamin B2

• RDA is 1.3 mg for men, 1.1 mg for women.
• Good for skin, eyesight, nervous system and making red blood cells.
• Food sources include mushrooms, rice, eggs and milk.

Thiamin/ vitamin B1

• RDA is 1 mg for men, 0.8 mg for women.
• Good for nerves and muscles and turning food into energy.
• Food sources include peas and other vegetables, pork, milk, and cheese.

Zinc

• RDA is 5.5 to 9.5 mg for men and 4 to 7 mg for women.
• Good for wound healing and making new cells.
• Food sources include meat, shellfish, milk, cheese and wheat germ.

The Department of Health also recommends that everyone should eat at least five portions of fruit and vegetables per day.

Fluids

Over half of an adult's total body weight is made up of water, which needs to be topped up when it is lost through sweating, and passing urine. Dehydration (not enough water in the body) can lead to headaches, tiredness and lack of concentration.

You should aim to drink at least 1.2 liters of fluid a day (between 6-8 glasses). Ideally, this should be water, but it also includes other drinks like squash, fruit juices, milk, tea and coffee. You should drink more when the weather is hot, and during and after exercise because more fluid is needed to compensate for what is lost from your body.

If you drink alcohol, try not to exceed the maximum daily intake which is 3 to 4 units for men and 2 to 3 units for women. One unit counts as a single, 25ml measure of spirit, 125ml (small glass) of wine, or half a pint of standard strength lager, cider or beer. Drinking more than this can have a negative effect on your health. Excess drinking can increase your risk of some cancers, heart and liver disease.

Supplements

If you eat a varied and balanced diet, you will usually get all the vitamins and minerals that your body needs. Sometimes, if you do not get an adequate amount of a certain vitamin - for example, due to a medical condition - you may benefit from taking a vitamin supplement. Your doctor will be able to advise you about this.

If you choose to take a multivitamin, you should make sure that it does not contain high doses of any one particular vitamin or mineral. High doses may be unnecessary, and if they are higher than the RDA (recommended daily allowance) for that vitamin or mineral, they can be harmful.

Therefore, you should not take more than the recommended dose, and you should not take them for too long, as doing so can cause harmful effects, such as stomach pain, constipation and vomiting. This is because some of the vitamins and minerals you need, such as iron and vitamin A, are stored in your body and taking them in a daily supplement can cause a harmful build up. You should always seek medical advice before taking supplements and remember that they are no substitute for a balanced diet.