Frank Horwill



  • These articles were first published many year's ago and whilst some are as relevant today as they were when new, many are now mostly of historical interest as modern research and coaching methods have superseded them.

The Enigma of Phosphorus

By Frank Horwill

"Warning: excessive consumption of this drink may damage your bones" The average 70-kilogram man has 680,000 milligrams of phosphorus in his body. It is an essential nutrient, and sufficient quantities are necessary for calcium to do its job in the system, yet too much phosphate can increase calcium needs, which, if not met, can render the individual calcium- deficient. A junk-food diet is rich in phosphorus and can produce a relative calcium deficiency and all the problems that this entails. Ideally, the dietary calcium-phosphorus ratio should be about 1 or 2:1.

The phosphorus RDA has recently been fixed at 900mg. In 1980, in the USA, it was fixed at a trivial 100mg per day. In the UK, the daily intake is about 1200-2000mg. Good food sources include milk and milk products, nuts and wholegrain cereals, poultry, eggs, fish, meats and legumes.

B vitamins are only effective when combined with phosphate in the body. A very important use in the athlete is the phosphorus-containing compound, adenosine triphosphate (ATP), which is involved in all exercise, short or long. Its other activities include: development of bones and teeth, multiplication of cells, activation of some enzymes and vitamins, and maintenance of body neutrality. It also participates in carbohydrate metabolism.

But are athletes getting too much?

Quite possibly athletes are ingesting three times the RDA. Dr Tim Noakes, the eminent physiologist at Cape Town University and author of 'The Lore of Running' (one of the greatest books ever written about road running) and four other scientists decided to carry out an investigation into the causes of shin-soreness. To do this, they brought together 12 sufferers from different sports (not just runners).

Their research was mainly confined to the type of training being done before the onset of the condition, what surfaces were mostly used, the strength of specific leg muscles and the gait of the foot on landing. Almost as an afterthought, they did a mineral assessment of each athlete. To their astonishment they found that they were all below the average calcium level.

Why was this? Their diet was examined and they were all found to be heavy consumers of cola-based drinks. These drinks invariably contain phosphorus and so do some food additives. I knew one 5,000m runner of note who consumed a giant-sized container of a cola drink after every training session. He trained twice a day and, coincidentally, he was invariably injured every three months. It may well be a suggestion that a public health warning, similar to that on a packet of cigarettes, be stamped on every tin and bottle: 'Excessive consumption of this drink may damage your bones'.

The simple fact is that the more phosphorus that is ingested, the more calcium intake must be increased proportionately. The formula is straightforward: junk food + soft drinks = excessive phosphorus = extra calcium or possible injury. Other things that affect calcium absorption are the phytates in bran and unleavened bread (including chappatis). Adequate vitamin D is also required for calcium to work properly; the same applies to an adequate supply of magnesium (found in nuts).

Yet phosphate boosting improves performance

It must be remembered that on average we possess 1,700,000mg of calcium in our bodies, and 99 per cent of it is needed for our bones and teeth. That said, it is astonishing to learn that phosphate boosting to improve performance in distance runners is producing good results. As stated, ATP and CP, two high-energy chemicals which provide the energy necessary for muscle contractions, also prevent unwanted increases in muscle acidity and may also increase the flow of oxygen from the red blood cells to the muscles.

Several studies are worth noting. In the first, four grams of sodium phosphate per day were given to runners at the University of South Florida, which lowered lactic-acid levels and increased the V02 max of all 10 athletes involved. Yet another study at Brigham Young University involving 11 active people who ingested 'Slim-O-Stam' (a phosphate supplement) failed to bring any improvements. Research at Adelphi University confirmed these findings.

However, at Old Dominion University, the exact method used by the University of South Florida on experienced triathletes saw the lactate threshold lifted by 10 per cent, the V02max by 9 per cent, and an 8 per cent improvement in a well-used time trial. The latest research score is: four in favour, three against. One drawback is that no women were involved in the experiments, nor was anyone over 30 years of age.

However, don't rush out and buy a phosphate supplement just yet. There is a twist in the findings. Phosphate supplements appear effective only in maximal work of not more than five minutes duration. The four grams have to be taken in single gram doses for three days with the last ingestion three hours before competition. Another little trifle is that training can lift blood phosphate levels more than supplements. If they are going to be used, calcium intake must be increased pro rata. High- calcium content foods include milk, cheese, broccoli, legumes, green leafy vegetables, nuts, seeds, peas, beans and lentils. Since milk products are often linked to allergies, it is unwise to rely on them as the main source of calcium. Milk also lacks magnesium.

Phosphorus is, indeed, an enigma.