National Nutrition Week takes place from 9 to 15 October each year, and this year the theme is: “Rethink Your Drink – Choose Water!"

Proper hydration is vital for good health and well-being. Poor hydration can negatively affect one's mood, concentration and performance, and have recently also been linked to an increased risk of chronic disease.

The Nutritional Information Centre at Stellenbosch University (Nicus) has compiled the following guide to help consumers make the best choices on what and how much to drink.

What should we drink every day?

Fluid intake in healthy adults is regulated by thirst. Water is an essential nutrient for life and it is considered the ideal drink to quench thirst and ensure hydration. Ironically, it is often ignored as part of our dietary recommendations.

Despite the benefits of water, many people prefer other drinks such as cool drink, fruit juice, coffee, tea, milk or sport drinks. These beverages could contribute to a person's daily energy intake, for instance, a glass of regular sweetened carbonated cool drink provides at least 418 kJ, while a glass of artificially sweetened cool drink contains less than 5 kJ, making the latter a far better choice for an overweight or inactive adult.

The increase in obesity and lifestyle diseases such as diabetes and heart disease highlights the need for greater awareness of better food and drink choices to help attain and maintain a healthy body weight. Healthy choices are complicated by the wide range of “functional" food and drinks, such as micronutrient enriched water or “cancer fighting teas", such as green tea, and other products offering health benefits. Faced with all these choices, consumers may need some guidance on how to include these beverages into their diet.

How much?

The National Research Council (NRC) recommends a daily water intake of about 1ml/kcal energy expenditure, which translates to about 8 glasses of water per day. This recommendation is based on an average-weight male (+/- 70kg), and there is no single formula that fits every individual or every situation as water intake recommendations also depend on other factors such as activity, humidity, climate, body temperature and body composition.

Water is part of every cell in the body and on average it comprises 50% of a woman's body weight, and 60% in men. Every system and function in the body depends on water. For example, water helps with the digestion of food, it carries nutrients to cells and it provides a moist environment for ear, nose and throat tissues. The amount of fluid consumed per day is approximately equivalent to the amount lost. Mild dehydration affects a wide range of cardiovascular and thermoregulating processes and responses. Dehydration of 3-5% of body weight, decreases physical strength and performance, and is the primary cause of heat exhaustion. Daily turnover of water is approximately 4% of total body weight and even higher proportions in children. Water losses from the lungs and skin (insensible losses; 500 – 1000 ml/day) are responsible for approximately half of the daily turnover and sensible losses from stools (50 – 100 ml/day) and urine account for the rest of the daily losses. Yet, despite changes in body composition and function as well as the environment, most healthy people manage to regulate daily water balance well across their lifespan.

Why is water the best possible choice?

Water is highly recommended for daily fluid intake. Despite the focus on hydration and de-hydration in many official reports, some studies have shown that plain water consumption is associated with better diets, better health behaviours, and a lower burden for chronic disease. It provides no additional energy, which makes it ideal for overweight or inactive adult. It also provides variable amounts of minerals such as calcium, magnesium and fluoride, depending on its source.

In most developed Western societies, diets provide an excess of total energy, which is associated with obesity and so-called lifestyle diseases. Although plain water fulfils almost all the fluid needs of healthy adults, individual preferences, perceived needs, taste, cultural, social and other factors have resulted in the availability of a variety of beverages. Some of these beverages contribute significantly to the intake of total daily energy and other nutrients. Depending on the frequency and amount consumed, the intake of energy and/or other nutrients may become inappropriately high.

South Africa has a heavy burden of infectious diseases (such as HIV/AIDS and tuberculosis) existing alongside diseases of lifestyle (non-communicable diseases) such as undernutrition, overnutrition, diabetes, hypertension and cancer. Diet-related non-communicable diseases account for 28% of the total burden of disease in South Africa, and are thought to be linked to the process of societal transition,  urbanisation and Westernisation from a traditional rural lifestyle – the so-called South African 'nutritional transition'. Specific dietary and lifestyle changes have been observed in the consumption of alcohol, tobacco and food – particularly a shift to a diet high in sugar, salt and saturated fat – and the reduction in physical activity.

South African adolescents and school learners are at an increased risk for environmental factors that cause obesity. For example, they are more likely to consume sugar-sweetened drinks, they are less likely to compensate for “fast food" energy, and they generally consume more energy-density foods (e.g. sweets, chocolate, and chips).

In South Africa, as in many other countries, obesity and overweight are mainly caused by an imbalance between energy consumed and energy expended:

• an increased intake of energy-dense foods that are high in fat or added sugars; and
• a decrease in physical activity due to the increasingly sedentary nature of many forms of work, changing modes of transportation, and increasing urbanisation/development.

Recommendations for South Africans

• Water fulfils almost all the fluid needs of healthy adults. Women should drink at least 4 glasses (250ml) and men at least 6 glasses (250 ml) of clean safe water per day. Children should drink water when thirsty and limit their intake of milk to 600 ml per day (from the age of 5 years all children and adults should drink low fat or fat free milk) and fruit juice to 240 ml per day.
• Drinks should not contribute to more than 14% of total daily energy intake.
• Schools should encourage children to meet their fluid needs with water and provide clean safe water, and limit the availability of other cool drinks/juices.
• Sweetened cool drinks, such as carbonated cool drinks should be limited to no more than 240 ml (approximately one standard cup) a day. These drinks should be avoided by diabetics and inactive and/or overweight adults and children.
• Fruit and vegetable juices (100% juices) and sports drinks should be limited to no more than 240 ml (approximately one standard cup) a day.
• Diet- or artificially-sweetened cool drinks could replace sweetened drinks in a varied diet (up to four servings of 240 ml a day).
• Unsweetened coffee and tea: Adults should limit their intake of caffeine drinks to no more than 4 cups of coffee per day or 8 cups of tea per day. Preferably, these should be with fat free or low fat milk and no sugar.

Access the South African Food Based Dietary Guidelines and recommendations for healthy eating and weight loss at: http://www.sun.ac.za/english/faculty/healthsciences/nicus/how-to-eat-correctly.

For more information contact the Nutrition Information Centre at Stellenbosch University (NICUS) or a dietitian registered with the Health Professions Council of South Africa.

References from the scientific literature used to compile this document are available on request.

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