BackWhat you eat isn’t what your body gets
Each macronutrient depends on the other to maximize its absorption and bioavailability
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All foods are not created equal, so the key to improving health and maximizing nutrition is to pay attention to the small differences that exist within foods of the same category or class. Cooking, chopping and masticating separate the nutrients from the food. These processes make the nutrients available for the body to be digested and absorbed easily.
For instance, eggs, milk, paneer (cottage cheese) and lean poultry all contain protein and the nine essential amino acids, but each provides the body with protein at different rates; therefore, each differs in the quantum of protein it can make available to the body. Protein and the essential amino acids build muscle, prevent hair fall, synthesize hormones and improve skin, among other things.
The unit for measuring how much protein a certain source of food can provide is called biological value, or BV. For instance, the protein in chicken has a BV of 79. Eating 100g of chicken does not mean your body is getting 100g of protein; 100g of chicken provides about 20g of protein and the amount that will be absorbed will be—BV percentage (0.79) multiplied by 20—15.8g.
For quick reference, one lightly cooked egg has a BV of 100. One whole egg contains 6.29g of protein, which means that with a BV of 100 the entire 6.29g of protein is ingested, so eggs are an excellent source of protein. Whey protein, in protein shakes, which contains about 24g protein, has a BV of 104. In the case of cow’s milk, 100ml has about 3.3g of protein and the BV is 91. A single egg white also contains 3g of protein, with a BV of 88; 100g of cooked rice (both white and brown), which has 4.6g of protein, has a BV of 74.
Surprisingly, many of the vegetarian sources of protein have a low BV. So a 100g of soy, which contains about 36g protein, has a BV of just 57. Also, soy protein is missing in the essential amino acid methionine, which is why it must be combined with a grain like wheat or rice, which contains methionine, for the body to get all of the nine amino acids. This increases overall calorie intake.
For the most part, the bioavailability of macronutrients—carbohydrates, proteins and fats—is 90% of the amount of food if all of the macronutrients are eaten together because each of these have specific, interdependent bodily functions. For instance, protein strengthens bones and tissues, but its optimum utilization depends on carbohydrates like grains which provide sustained energy. Omega fats combine with proteins to strengthen cell walls and also store vitamin E that must interact with vitamin C. This is why eating a balanced meal is important. Each macronutrient depends on the other to maximize its absorption and bioavailability. Brown rice enriched with a few almond shavings, with skimmed paneer or chicken with a heaping of salad or stir-fried vegetables is an example of a balanced meal.
Soups and salads often lack the necessary amount of protein. A meal of grilled chicken and salad, often seen as healthy, falls short on carbohydrates and fibre.
Rice and dal, or khichdi, lack the micronutrients and water-soluble vitamins found in vegetables.
Both internal and external factors affect the bioavailability of macronutrients. The internal factors include age, gender, overall health and nutrient status and pregnancy. The BV goes down with age, or if you are unfit, because your body is not processing the food efficiently.
The external factors include dietary and food choices, including food combinations and cooking methods. For instance, eating lightly cooked carrots, tomatoes and spinach together and adding a dash of virgin olive oil improves the bioavailability of the carotenoids that they contain. Carotenoids are not bioavailable from raw foods and are fat soluble so absorption improves with olive oil.
In this case, cooking enhances bioavailability. Cooking protein-based foods at high temperatures, on the other hand, upsets the amino-acid links in the protein and affects the BV of the food. Charred tandoori chicken and smoked meats are a case in point. Not only do they lose their full complement of amino acids, they may even be carcinogenic. Charring and smoking foods increases the carbonization of foods and carbon is known to be toxic.
Improve bioavailability
®Ensure that you have all the macronutrients at each meal, including snacks. Combine a fist-size serving of protein foods like skimmed paneer, lean chicken, egg whites or whole eggs, with some high-fibre complex carbohydrates like wholegrain bread, or roti with vegetables for micro nutrition and antioxidants, with a dash of virgin oil for good fats.
®Remember that foods which are rich in calcium, like skimmed paneer, are best had with grains and not with leafy greens for maximum bioavailability. This is because leafy greens like spinach contain nutrient compounds like phytate which inhibit the absorption of calcium. Grains have to be combined with other macronutrients to improve bioavailbility. Rice, dal and almonds offer more bioavailability than rice and dal alone, chana (chickpea) with sesame seeds also increase overall bioavailability.
®Eat a mix of raw and cooked food to improve bioavailability. Accompany meals with a salad or vegetable juice. Sprinkle cinnamon powder, flaxseed on meals or add lime juice to all meals to improve iron absorption. At the same time avoid overcooking food or adding soda to hasten the cooking of chana, rajma and beans, as baking soda lowers bioavailability.
®Ensure that there is some omega nutrition in the diet in the form of virgin cold-pressed oils, oily fish, powdered/ground flaxseed, or nuts like almonds and walnuts.
®Eat at regular intervals to improve digestive function and exercise every day to maximize bioavailability.
Madhuri Ruia is a nutritionist and Pilates expert. She runs InteGym in Mumbai, which advocates workouts with healthy diets.
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