Part 3: Water, Metabolism, and Biotics
Based on the book "The Science of Nutrition" by Rhiannon Lambert
It is not easy to find even one system of the body that does not require water. Water enables the circulatory system to carry essential oxygen and nutrients to cells. Our kidneys need water to filter out waste products. It helps us cool off via sweat when we are too hot. It helps the digestive system do its job. And the list goes on! When it comes to the brain, 75 percent of its mass is water, so alongside the bodily processes, hydration also plays a crucial role in regulating mood, productivity, and concentration. Drink 2.7–3.7 liters of water every day. A typical mug or glass has a capacity of 7oz (200ml), so you’d need to have 11.5–15.5 drinks a day. Bear in mind that these are the recommended daily intake amounts and some people may need more. Aim for 15.5 cups (3.7 liters) daily if you easily get to 11.5 cups (2.7 liters). Signs of dehydration include dry mouth, dark yellow urine, feeling tired, thirsty, and dizzy, and urinating fewer than four times per day. Studies show that at about 1 percent dehydration (equivalent to 1 percent of body weight water loss) there are negative effects on mental and physical function, which become more severe as dehydration increases. What is metabolism? Metabolism is the term used to collectively refer to every single chemical reaction that takes place in your body in order to keep it alive. Metabolism is closely linked to nutrition, because the food we eat provides the energy required to fuel metabolism. On average, we use 10 percent of energy intake on digestion itself, 20 percent on physical activity, and a whopping 70 percent by organs and tissues to keep the body alive. Every process in the body, from breathing to thinking, uses energy. A person’s basal metabolic rate (BMR) is the number of calories needed to sustain their life while they are sitting still. How the body metabolizes the energy it consumes is played out in a balancing act between two states—fed and fasted. During or after eating a meal, food is broken down and glucose is released into the blood for cells to absorb and use as fuel. When the body has obtained more glucose from food than is needed by cells, they stop absorbing it. The resulting increase in blood glucose levels triggers the release of insulin. Insulin stimulates liver and muscle cells to reverse the conversion of glycogen into glucose that takes place during the fasted state and, instead, absorb the surplus glucose in the bloodstream, convert it to glycogen granules, and store it for future use. Insulin also triggers the conversion of glucose to triglycerides (fats) in adipose tissue. Surplus fatty acids from the diet are also stored in adipose tissue. Several hours after eating, blood glucose levels drop, which triggers the pancreas to release glucagon. This stimulates the liver and adipose tissue to metabolize glycogen stores, which releases glucose into the bloodstream to make it available for the body to use as energy. After prolonged fasting, fat stores in adipose tissue are broken down into glycerol and fatty acids in the liver. Ketone bodies are a by-product of this reaction. Protein is used for fuel only as a last resort. WHAT ARE CALORIES? This unit of measurement is used to estimate how much energy there is stored in the chemical bonds of the foods we eat. Your body may not gain the full amount of energy that is released from foods. Foods full of fiber, like nuts, for instance, take more energy to digest and two people may absorb different levels of nutrients from the same quantity of the same foods. Gut health and the length of the intestines play a role in how much energy your body is able to absorb from foods. It’s important to remember that calories are not everything! A number definitely does not dictate how healthy you are or the quality of nutrition you consume. You could be in your body’s ideal calorie-intake range by eating a chocolate brownie for breakfast, lunch, and dinner, but this won’t provide you with all the key macronutrients, micronutrients, and fiber you need to be healthy and happy. Portions of Fruit and vegetables: 1 portion = 1 handful/3oz/3–4 heaped teaspoons cooked spinach/green beans = 1 medium tomato = 1 medium apple/orange/banana = 5oz of fruit juice (maximum per day). Portions of starchy carbohydrates 1 portion = 2 handfuls dried rice/pasta/couscous (less for 4 portions) = 1 fistsized baked potato = 2 slices bread. 2-3 portions of Protein 1 portion = half a handful salmon/chicken/steak = 4oz cooked beans/lentils = 1oz/palmsize nuts or seeds. 2-3 Portions of Dairy and alternatives 1 portion = 1oz/2 thumbs cheese = 7oz low-fat cow’s milk or unsweetened dairy alternative (4oz on cereal) = 4oz low-fat yogurt. The dried seeds of legumes are called pulses. They include lentils, chickpeas, black or pinto beans, soybeans, and kidney beans. These robust seeds contain varying amounts of the essential amino acids that make up protein. A 3.5oz (100g) serving of red lentils, chickpeas, or kidney beans provides 7.5g–8.5g of protein, which makes up a nice chunk of your daily requirement. You can save much money by getting more of your protein from beans rather than meat, adding lots of valuable fiber to your diet at the same time. Probiotics are live strains of bacteria consumed to directly increase the population of “good” bacteria in the gut. Prebiotic foods feed existing gut bacteria so they can thrive and work effectively. What are the benefits? Research suggests probiotics are mainly of benefit when your gut microbiome is out of balance, for instance, to relieve diarrhea caused by infection or after a course of antibiotics. Although studies are limited, certain types of bacterial strains have been found to reduce symptoms of irritable bowel syndrome, particularly bloating. Otherwise, a study found that eating fermented foods 1–5 times weekly is associated with a subtle change in gut bacteria. In general, though, healthy people should not require probiotic supplements. A key benefit of prebiotic foods is that different types of the non digestible fibers within the food are broken down by gut bacteria, which then produces gut protective short-chain fatty acids. Some studies show that eating a type of dietary fiber called inulin can help maintain the gut’s mucus barrier and prevent inflammation. It’s best to increase prebiotic food intake gradually, to avoid bloating.
