What foods should you avoid for optimal running?

By Angela Bentley

As dieticians we are continuously giving advice to runners on what to eat to perform at their best.  While what we eat is extremely important, we can destroy our best efforts by putting other incorrect substances into our bodies. Today I will be discussing three things that I consider to be potentially detrimental to your performance and health.


We know it is tempting to enjoy a drink or two after a good training session or race, but it may be better to opt for an orange juice. You may not think that a few casual drinks will have a huge impact on your athletic performance, but sadly its effects are widespread and could be the cause of disappointing results. Alcohols effects include:

  • Impaired muscle growth and recovery due to interruption of sleeping patterns and protein synthesis.
  • Increased risk of injury due to blood flow changes in soft tissue.
  • Reduced endurance, strength and speed.
  • Increased risk of dehydration due to alcohols diuretic effects and alteration of judgement
  • Altered ATP production pathways, thus lower energy levels.
  • Increased fat storage and micronutrient depletion. This is worsened by the fact that we often skip meals or make unhealthy food choices when drinking.

For these reasons it is probably better to stay away from alcohol during peak training and races. This being said, alcohol in moderation (one drink for women and two for men) has its pro’s. It can be beneficial to the cardiovascular system, prevents certain diseases and has social and psychological benefits. If you do not have any condition that contra-indicates alcohol consumption by all means have a drink during the quieter periods of training.


In this day and age I don’t think there are many people under the impression that cigarettes are healthy for you. But if you need further reason to throw away that box, consider how it impacts your running performance. Smoking decreases your lung capacity and VO2 max which in turn leads to lower energy levels. It also weakens your immune system, increasing sick days and decreasing training.

Quitting smoking is definitely not easy, but there is no doubt that you will feel the difference in your training. It is human nature to replace one addiction with another- why not replace yours with the endorphins that come from a killer run?


Sports supplements are dangerous for a completely different reason to alcohol and cigarettes. Their risks lie in the fact that the supplement industry is unregulated; this means that the producers of supplements do not have to give a complete ingredient list or prove that the product contains ingredients listed. They also don’t need to prove the efficacy or safety of their products in order to get it on to the market. Using a supplement that you are lead to believe is perfectly safe could cause you to test positive for banned substances or be detrimental to your health. Effects include allergic reactions, toxicity of self-medication, overdosing and poisoning.

Some sports supplements carry larger risks than others. For example, it is unlikely that a high carbohydrate gel or bar would contain banned substances. There are also companies like Informed Choice that are there to offer some piece of mind. They test products for banned substances and offer an endorsement if their requirements are met. It is advisable to consult with a dietician or sports physician before using a sports supplement. FutureLife® High Protein makes for a fantastic carbohydrate and protein blend and carries the added benefit that it is endorsed by Informed Choice.

Our bodies are amazing machines and we need to respect them. We need to be careful to consume only what is beneficial to us. Let’s face it; we are very cautious about putting the right fuel into our cars, should we not be far more careful with our bodies?