More recent research suggests that the relationship between hydration and decompression illness is more complicated than previously thought. While dehydration is generally undesirable, there is currently insufficient evidence to suggest that aggressive pre-dive fluid loading significantly reduces DCI risk.
Conversely, excessive fluid intake immediately before diving is not recommended. Overhydration has been associated with an increased risk of immersion pulmonary oedema( IPO), particularly in susceptible individuals, those with cardiovascular risk factors and divers undertaking strenuous activity in cold water.
The most sensible advice is to maintain normal hydration throughout the day rather than trying to rapidly‘ water load’ before a dive.
A practical way of monitoring hydration status is to observe your urine colour. NHS guidance suggests that pale yellow urine is generally consistent with adequate hydration, while darker urine may indicate that additional fluids are required. Although urine colour should not be used as the sole measure of hydration, it is a simple and accessible guide for divers preparing for a day’ s diving.
Diet quality and cardiovascular health
While there is no proven‘ diving diet’, the quality of a diver’ s overall diet is likely to be important. Good nutrition supports cardiovascular health, recovery from exercise and general wellbeing.
Current evidence favours dietary patterns rich in:
■ Fruit and vegetables
■ Whole grains
■ Legumes
■ Nuts and seeds
■ Fish
■ Minimally processed foods
PHOTO: SHUTTERSTOCK
Examples of the Mediterranean diet
These foods form the basis of dietary patterns such as the Mediterranean diet, which has well-established benefits for cardiovascular health.
Many of the physiological stresses associated with diving, including inflammation and oxidative stress, are also influenced by overall health status. Oxidative stress is an imbalance between unstable molecules called free radicals and the body’ s ability to neutralize them with antioxidants. As a result, maintaining a balanced diet is likely to support fitness to dive even if specific diving-related benefits have not been conclusively demonstrated.
Oxidative stress and antioxidants
Researchers have become increasingly interested in how diving affects the cardiovascular system. Exposure to increased oxygen pressures, physical exertion and environmental stressors may contribute to oxidative stress and temporary impairment of endothelial function, which refers to how well the lining of blood vessels functions.
Several studies have investigated whether antioxidants might reduce these effects.
One study found that vitamins C and E taken before diving reduced some of the endothelial dysfunction observed after a dive. However, the study did not demonstrate a reduction in decompression sickness, so routine supplementation cannot currently be recommended solely for diving purposes.
A more practical takeaway is that divers should consume a diet naturally rich in antioxidants. Fruits, vegetables, nuts, legumes and whole grains provide a wide range of antioxidant compounds while also supporting overall health.
Dark chocolate and diving
One of the more unusual areas of diving nutrition research concerns dark chocolate.
A small study found that consuming dark chocolate before a dive appeared to improve endothelial function after diving. The proposed explanation is that dark chocolate contains flavonoids and other antioxidant compounds that may support vascular health.
While this finding is interesting, it is important not to overinterpret the results. The study did not show that dark chocolate improves nitrogen elimination, prevents decompression illness or makes diving safer.
At present, dark chocolate should be viewed as an interesting area of research rather than a proven diving aid.
A tough shore entry and a rescue: both require cardiovascular health
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