Vitamins, minerals and water
Vitamins and minerals are not a source of energy, but they are needed by the body to maintain your health. Inadequate vitamins or minerals can certainly have a harmful impact on your running performance. However, if you eat a balanced diet of largely unprocessed foods, it is likely that you are getting enough of the key vitamins and minerals.
In judging your vitamin and mineral intake you should take the following into account:
- if you are eating packaged or processed foods, they may have fewer vitamins and minerals than fresh food;
- intensive food production (e.g. farming, storage and transportation) means that some foods don’t have as many minerals and vitamins as their less intensively‑produced counterparts;
- if you sweat a lot (e.g. because you are running in a hot climate) you may lose essential minerals in your sweat which need to be replaced;
- regular exercise increases your vitamin and mineral requirements compared with sedentary people, because they are needed for metabolism, maintenance of tissue and manufacture of red blood cells; the recommended daily allowances (“RDAs”) that are published by the Government are a guide for the general population, and you may well need to consume more than these guidelines;
- high intensity training may weaken your immune system, and increased intakes of vitamin C will help to boost your natural defences;
- it is possible to take too much of some vitamins and minerals (particularly vitamins that are not water soluble, such Vitamins A, B6 and D); large excesses of these can lead to nutritional imbalance and, in extreme cases, serious illness.
On the whole, you should aim to get your vitamin and mineral intake from your diet. However, many active people choose to supplement their diet by taking a multi-vitamin supplement. This provides insurance, in case the vitamins are lacking from the food you eat. But you should not take doses of vitamins or minerals significantly above the recommended daily allowance without first seeking medical advice, and certainly not of vitamins that are not water soluble.
Water is by far the most important nutrient in the runners’ diet. Yet for some reason, it is often neglected in books and articles about running.
You should probably drink more water than you do right now. This is for two reasons. First, most people – even if they don’t do any exercise – don’t drink enough water. Second, as a runner you need more water because you lose water through sweat.
Water is important because it helps to regulate your body temperature (through sweating), and it makes up 82% of blood and determines its viscosity. Water is also stored with glycogen in your muscles, so if you don’t drink enough water your body will not be able to store energy. High water intake will also help your body to regulate toxins, and keep your skin healthy. As we shall see in Chapter 7, dehydration can lead to poor performance; but excessive hydration is also dangerous.
As a very approximate rule of thumb, you need about 1 litre of water for every 1000 kcal you consume during the day (this is your base water intake; you need extra when you are exercising). You also need more in hot or humid weather. This means that if you have a daily calorie intake of 3000 kcal, you need to drink about 3 litres of water each day. That is a lot, and may well be more than you are drinking at the moment.
Try to get into the habit of drinking a pint of water when you first get out of bed; and then sip water throughout the day. Many healthy people keep a sports water bottle next to them at work, so that they can sip frequently.
The following drinks are diuretics – that is, they make you urinate and so increase the amount of water you need:
- coffee and tea
- caffeinated drinks such as cola
- alcoholic drinks
If you drink any of these, you should aim to increase your water intake by at least the volume of the diuretic drink. (So if you have a 350ml can of cola, try to drink 350ml extra of water as well.)
The urine colour test
It is fairly straightforward to check if you are drinking enough, by looking at the colour of your urine. If your urine is clear, then you are well hydrated. If it is yellow, or dark, then you are dehydrated and need to drink more. (The University of Connecticut has developed a guide, like a paint colour chart, to enable you to judge your hydration.) Note that your urine may be discoloured by some vitamins and minerals – for example, Vitamin B6 tends to make your urine fluorescent yellow – so that if you take vitamin supplements you may not be able to judge your hydration so easily by looking at the colour.
Rapid weight loss is also a good indicator of dehydration. If you weigh yourself after a workout and find you have lost a lot of weight, then you should not congratulate yourself, but go to the kitchen and get yourself a pint of water or a sports drink.