Nutrition journey: Part 5 – Hydration and fluid

What is your beverage of choice?

If you chose water, then congratulations on recognising the importance of maintaining your body’s fluid balance.

If you answered milk, pat yourself on the back for taking good care of your bones.

If your answer is carbonated fizzy drinks, think again…

Before getting too comfortable reading this blog, pour yourself a glass of water.

 

Water is an essential nutrient, more important to life than any other nutrient. The body also need more water each day than any other nutrient.

Water constitutes about 60% of an adult’s body weight and is responsible to:

  • Carry nutrients and waste products throughout the body
  • Maintain structure of large molecules such as protein and glycogen
  • Participates in metabolic reactions
  • Serves as solvent for vitamins, minerals, amino acids, glycogen and other small molecules so that they can participate in metabolic activities.
  • Acts as lubricants and cushion around joints and inside of eyes, spinal cord, amniotic sac surrounding fetus (in pregnant ladies)
  • Aids regulation of normal body temperature, as the evaporation of sweat from the skin removes excess heat from the body.
  • Maintains blood volume

Water needs vary depending on diet, activity, environmental temperature and humidity. General water requirement is difficult to establish. The recommendation are sometimes expressed in proportions to the amount of energy expended under average environmental conditions. The recommended water intake for a person who expend 8000kj a day is for example 2-3 litre per day. This recommendation is in line with the Adequate Intake for total water set by the DRI committee.

The obvious dietary source of water is water itself and other beverages, but nearly all food contain water. Most fruit and vegetables contains more than 60% water and up to 99%, while some meats and cheese contain up to 50% water. See table 5.1 for foods and their water percentages.

FoodsWater percentage (%)
Water100
Fat-free milk, strawberries, watermelon, lettuce, cabbage, celery, broccoli, spinach 90-99
100% fruit juice, yogurt, apples, grapes, oranges, carrots80-89
Shrimp, banana, corn, potatoes, avocado, cottage cheese, ricotta cheese70-79
Pasta, legumes, salmon, ice cream, chicken breasts60-69
Ground beef, hot dogs, feta cheese50-59
Pizza40-49
Cheddar cheese, bagels and bread30-39
Pepperoni sausages, cake, biscuits20-29
Butter, margarine, raisins10-19
Crackers, cereal, pretzels, peanut butter, nuts1-9
Oils and sugars0

The body must excrete 500ml (2 cups) of water a day, as urine, to carry away all the waste produced by metabolic activities. In addition to urine, water is lost from the lungs as vapor and from the skin as sweat. The amount of fluid lost from each sources varies, depending on the environment (such as heat and humidity) and physical conditions (such as exercise or fever). On average daily water losses is about 2.5 litre

Water intake should be significantly higher than water losses to prevent dehydration. Table 5.2 indicates signs and symptoms of dehydration.

Body weight loss (%)Symptoms
1 – 2 Thirsty, fatigue, weakness, vague discomfort, loss of appetite
3 – 4Impaired physical performance, dry mouth, reduction in urine, flushed skin, impatience, apathy
5 – 6Difficulty concentrating, headache, irritability, sleepiness, impaired temperature regulation, increased respiratory rate.
7 – 10Dizziness, spastic muscles, loss of balance, delirium, exhaustion, collapse

One of the most common causes of dehydration is water loss during exercise without replacing the water loss. In many cases fluid and mineral loss in sweat can be replaced by drinking plain cool water or eating regular food. Other cases however demand rapid replacement of fluid and electrolyte. Endurance athletes can easily lose 1.5L or more fluid during each hour of activity. To prepare for fluid losses an athlete must hydrate before exercise and even in the days before an event to ensure maximum hydration at the start of an event. To replace fluid loss the athlete must rehydrate during and after exercise. Table 5.3 explains the hydration schedule for endurance athletes

WHEN TO DRINKAMOUNT OF FLUID
2 – 3 hours before activity2 – 3 cups
15 min before activity 1 – 2 cups
Every 15 min during activity½ – 1 cups
After activity 4 cups for each kg lost after exercise
  1. During exercise when sweating occurs,  small amounts of electrolytes (electrically charged minerals sodium, potassium, chloride and magnesium) are lost with water. Losses are greater in beginners; training improves electrolyte retention. To replenish electrolyte loss athletes ordinarily need only to eat a balanced diet that meets energy and nutrient need. In eventscompares popular sports drinks. more than an hour or in very hot, humid conditions, sports drinks may be needed to replace fluids and electrolytes.

Hydration is critical to optimal performance. As stated previously water best meets the fluid needs of most people, yet manufacturers market many good-tasting sports drinks that delivers both fluid, electrolytes and carbohydrates. The term sports drink generally refers to beverages that contains carbohydrates and electrolytes in a specific concentration.

Lets take a closer look at the most popuelectrolyte solution with less sugar and carbohydrates possibly after a hot, humid higer intensityrink on the market:

  1. Energade (100ml):             130kj;     8g carbohydrates; 6g sugar
  2. Energade lite (100ml):       60kj;       3.2g carbohydrates; 2g sugar
  3. Powerade (100ml):            129.5kj;   7.3g carbohydrates; 5.5g sugar
  4. Lucozade (100ml):             265kj;   15g carbohydrates;  13g sugar
  5. Lucozade zero (100ml):    9kj;      0, 1g carbohydrates; 0, 1g sugar
  6. BOS Sport (100ml):            114kj; 6.4g carbohydrates; 6.4g sugar
  7. Game (100ml):                    122kj;  7.2g carbohydrates;  6g sugar
  8. Vitamin water (100ml):     85kj;     5.2g carbohydrates;  5.2g sugar
  9. Oshee (100ml):                   5kj;         0g carbohydrates;    0g sugar
  10.  If you are looking for a hydration and electrolyte solution with less carbohydrates and sugars, possibly after a hot and humid workout, that was less streneous, you would rather look out for lite options like Energade lite, Lucozade zero, and Oshee. These products also has a stabilizing effect on bloodsugar levels. However after finishing a streneous prolonged workout session of 2-3 hours or more, in humid, hot weather, you might need a sports drink with higer carbohydrate content.

Choose wisely when choosing a sports drink.

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