// Maximise nutritional benefits with the cohesive food strategy
by Teresa Doherty
Did you know that eating certain foods in combination can enhance their nutritional value? Foods and their nutrients work together as a cohesive dynamic team where they enhance or reduce another’s nutrients action. Some nutrients remain passive until another nutrient has made them active and some inhibit or promote absorption; along with this, there are probably hundreds of plant chemicals whose functions are yet to be discovered. Here are some of the ways you can achieve food synergy.
Calcium is the most abundant mineral in the body: the contraction of muscles, release of neurotransmitters, regulation of heartbeat and clotting of blood all rely on adequate calcium absorption. Calcium interacts with a number of minerals, but it best functions in combination with magnesium – although an imbalance in one can affect absorption and metabolism of the other.
Vitamin C from food has more value than from supplements – research has shown that ascorbic acid from natural citrus extract, containing bioflavonoids, proteins and carbohydrates, is more slowly absorbed and more bioavailable (able to reach the body’s circulation) than synthetic ascorbic acid from supplementation. The effects of grapefruit juice are complex and have been widely studied – it provides good levels of vitamin C and helps to protect against cardiovascular disease and cancers.
Research has found it to be an inhibitor of the intestinal enzyme system P-450, which is responsible for the metabolism of many drugs. The coingestion of grapefruit juice with drugs such as diazepam, simvastatin and prednisolone increases their bioavailability and therefore their side effects. For this reason, grapefruit juice ingestion should be avoided with certain drugs.
Iron is critical for human life. It plays a central role in the formation of the haemoglobin molecule in red blood cells, where it functions in oxygen and carbon dioxide transportation. Iron also functions in several key enzymes in energy production and metabolism.
Dietary iron is available from two distinct forms: ‘haem’ iron, which is bound to haemoglobin and myoglobin in animal products (efficiently absorbed) and ‘non-haem’ iron, which is found in plant food (poorly absorbed). It has been reported that the absorption of iron from rice was only one per cent and 1.3 per cent from spinach. It appears that the phytic acid in grains and the oxalic acid found in vegetables bind to the iron and reduce its absorption.
Vitamin C has been shown to optimise absorption of dietary non-haem iron by keeping it in its ferrous condition. Research has shown that the iron of maize, rice or black beans, which is normally poorly absorbed, was used 2 to 3.5 times better when vitamin-C-rich cauliflower was added to the meal. Further studies showed that adding 150g of papaya containing 66mg of vitamin C increased iron absorption five-fold. The amino acid cysteine binds to the iron and influences absorption up to two-fold by carrying it across the intestinal membrane. Good sources of cysteine are onions, garlic, oats, wheatgerm, broccoli and Brussels sprouts.
Research has shown that the absorption of iron from plant food is enhanced threefold by the presence of 100g of fish in the diet and twofold by the presence of 50g of meat. Tea and coffee contain plant polyphenols that bind to iron and inhibit non-haem iron absorption, with tea having the stronger effect. The effect is reduced if the beverage is taken well away from mealtime.
- A cup of tea reduces iron absorption by 75 to 80 per cent.
- A cup of coffee reduces iron absorption by 60 per cent.
Vitamin E food sources provide the different forms of this fat-soluble vitamin. A deficiency in fat from a very low-fat diet or fat malabsorption syndromes, such as coeliac and Crohn’s disease, can lead to vitamin E deficiency.
In supplement form, natural vitamin E containing mixed tocopherols, including the tocotrienols, offers the greatest health benefits. Studies have also shown that natural vitamin E supplements are better absorbed than synthetic varieties. Vitamin E supplements should be taken with food to improve availability.
Vitamin E interacts extensively with the other antioxidant nutrients, especially vitamin C and selenium. Selenium has been shown to be an essential trace mineral in maintenance of the pancreas and for the formation of pancreatic enzymes and thereby improves the uptake of vitamin E, whereas vitamin C assists in the regeneration and recycling of vitamin E. Eating a breakfast combining porridge oats for its selenium with flaxseed or almonds and a handful of berries will ensure good bioavailability of vitamin E.
There isn’t one single food that will provide us with all of our nutritional requirements and there isn’t one food that will prevent disease. However, by consuming a diet that provides good levels of vegetables, fruit, wholegrains, essential fats, fibre and lean sources of protein, you can achieve a good nutritional status.
By understanding how to mix certain foods together and ensuring the diet is varied and well balanced, optimal health can be achieved and retained.
Teresa is a nutrition expert with over 16 years’ experience in the health and fitness industry. She has worked as a freelance nutritional therapist and fitness instructor, as well as a college lecturer and assessor. She is also the founder of Green Apple Nutrition, offering solutions for a healthy diet and positive mental attitude (www.greenapplenutrition.co.uk)
NETWORK MAGAZINE • WINTER 2010 • PP38-39