FRUIT AND VEGETABLES FOR BOXING
How many fruits and vegetables does a boxer need to eat?
Do you need to eat fruit and vegetables when dieting?
What are the best fruit and vegetables to eat?
Is juicing fruit and vegetables good for boxing?
Everyone knows that fruit and vegetables are vital for health as they have been shown to reduce the risk of coronary heart disease, diabetes, and certain types of cancers (He et al. 2007; Key et al. 2011). It’s also common knowledge that fruit and vegetables, in combination with an adequate energy diet, can help reduce the risk of illnesses such as the common cold (Walsh et al. 2019).
However, many don’t realise that fruit and vegetables play an important part in performance and recovery.
This article will explain the benefits of fruits and vegetables for boxing and why, when and how many fruits and vegetables boxers need to consume per day.
Fruits and vegetables contain thousands of plant polyphenols which have a variety of subclasses. The four major classes of polyphenols are phenolic acids, flavonoids, stilbenes and lignans (Myburgh 2014). The colour of the fruit and vegetable determines the main contributing polyphenol (see table 1 below). These polyphenols have been shown to have a variety of benefits for the human body, and the more variety of polyphenols we consume, the greater the benefits we will have.
Table 1 Mybugh (2014) Types of polyphenol classes.
FRUITS AND VEGETABLES FOR GUT HEALTH
Fruits and vegetables contain high amounts of fibre and prebiotics. The recommended daily intake of fibre is 30 g. This amount reduces the risk of cardiovascular disease, diabetes, and bowel disease (Threapleton et al. 2013). Moreover, fibre intake helps promote a greater diversity of good bacteria in the gut and promotes satiety. This means that it can aid the digestion of key nutrients. It has been reported that a healthy gut with good bacteria can reduce the risk of illness but also depression, and anxiety (Bear et al. 2020).
Consuming a higher amount of fruit and vegetables, which are low in calories whilst high in micronutrients and fibre, will increase fullness when dieting. This is one of the reasons why those who consume a greater intake of fruit and vegetables tend to be leaner and healthier. However, consuming fruit and vegetables in smoothies and juices will decrease the fibre content and the mastication processes needed to chew the food. Flood-Obbagy et al. (2009) showed that consuming a whole apple compared to apple juice and sauce increased fullness to a greater extent (see figure 1 below). This is why we promote whole fruit and vegetables rather than juices and smoothies when making weight.
Figure 1. Hunger ratings following the consumption of apples, apple sauce and apple juice (Flood-Obbagy 2009).
The UK government recommend the general population consume at least a minimum of 5 portions of fruit and vegetables per day. However, it’s advised that athletes consume a greater amount of this and aim towards 8-10 portions per day (Appel et al. 1997; Hord et al. 2009). Taking part in excessive amounts of exercise creates a higher amount of muscle damage and oxidative stress that produces an overload of reactive oxygen species (see figure 2 below). A higher intake of antioxidants from fruit and vegetables will be required to scavenge the reactive oxygen species and help towards the repair and regeneration of muscle tissue.
Please note that most elite athletes and boxers do not take part in regular exercise like an ordinary person.
Figure 2 Pingitore et al. (2015) Inverted U of the magnitude of stress and exercise.
FRUITS AND VEGETABLES FOR RECOVERY
There is an abundance of studies investigating the effects of different types of fruit and vegetables on aspects of recovery from exercise. Fruit and vegetable derivatives have beneficial effects due to their high polyphenol content, scavenging reactive oxygen species and reducing inflammation. However, we now think that their beneficial effects may not be due to reducing inflammation but to improve blood flow so that key nutrients are delivered to help the repair of muscle tissue.
Montmorency tart cherry juice is a common supplement that has been shown to improve recovery and reduce muscle soreness (Hill et al. 2020; Doma et al. 2021). Current evidence suggests supplementing with two servings per day for 3 to 7 days totalling an intake of 1000 mg of polyphenols per day, to accelerate recovery (Bowtell and Kelly 2019).
Observational studies from Mediterranean countries have suggested that a Mediterranean diet is equivalent to consuming 1000 mg of polyphenols daily. This implies that consuming a diet rich in fresh fruits and vegetables may have benefits for recovery (Zamora-Ros et al. 2016). Other kinds of fruits and vegetables have also been reported to aid recovery, including but not limited to blueberries, elderberries, pineapple, watermelon, blackcurrant, pomegranate and beetroot (See table 2 below) (Mcleay et al. 2012; Clifford et al. 2016; Ammar et al. 2016).
A caveat to most of the studies reporting beneficial effects on recovery is that the non-supplemented groups i.e. control groups, were required to void their diet of polyphenols (eating a bland diet with no fruit and vegetables and polyphenol-containing drinks and foods). So far, we are unsure if it was the supplement having beneficial effects on recovery or reducing the polyphenol intake in the control groups which were the determining factor. This is one of the many reasons why we promote a whole food diet rich in wholegrain carbohydrates, fruits and vegetables to all of our boxers (See how to set up a boxing diet here https://boxingscience.co.uk/how-to-set-up-a-diet-for-boxing-part-1/
Table 2 Nutrition and supplement strategies to prevent and attenuate exercise-induced muscle damage (Harty et al. 2019).
FRUITS AND VEGETABLES FOR PERFORMANCE
Only recently have studies begun to investigate fruit and vegetables on performance as well as recovery. Research that has investigated beneficial effects on recovery immediately post-exercise noticed that performance was superior in the polyphenol groups (Rickards et al. 2021). Suggesting that it may not be that participants have improved recovery in this acute period, but they are still showing signs of improved performance from polyphenol supplementation.
Beetroot juice is a common supplement that has been known to improve aspects of performance, including aerobic and anaerobic endurance (Jones et al. 2014). Studies suggest that consuming 500 mg of dietary nitrates, which is the equivalent of 200 to 400 g of fresh beetroot, 150 minutes before exercise will have performance benefits, especially in the untrained (Murphy et al. 2014). A recent study by Porcelli et al. (2016) investigated the effects of a high nitrate diet on performance measures, including peak power during a repeated Wingate test. The high-nitrate diet outperformed the control diet providing evidence that consuming a high-nitrate diet potentially improves oxygen delivery (see table 3 and figure 3 below).
Table 3. comparison of a high nitrate diet and a control diet on exercise performance (Porcelli et al. 2016).
Figure 3a and b. Peak power achieved by control diet and high nitrate diet during 6s wingate cycle ergometer tests.
Table 4. Classification of vegetables according to nitrate content.
In addition, Van der Avoort et al. (2018) investigated the effects of a high nitrate intake from vegetables on the health-promoting and ergogenic effects of dietary nitrates. They found that consuming a diet high in nitrate vegetables (see table 4 and 5) had beneficial effects on arterial blood pressure and aerobic performance.
Table 5. Nitrate-rich vegetables per 100g of fresh weight.
Furthermore, Whyte et al. (2019) found that consuming a 400 ml berry smoothie before a reaction time test improved cognitive performance at 2, 4 and 6 hours after consumption in healthy adults (see figure 4 below). Demonstrating that consuming flavonoid-rich polyphenols such as blueberries, raspberries and strawberries may improve cognitive performance for up to 6 h.
Figure 4. Mean reaction time during a computerised test with berry smoothie and placebo (Whyte et al. 2019).
SUMMARY
We now know that consuming a variety of fruit and vegetables along with an adequate energy diet can improve health but also performance and recovery and increase satiety making dieting easier. This is why we promote that all of our athletes aim for 8 to 10 portions of different coloured fruit and vegetables per day. Although we know that consuming whole fruits and vegetables is great for satiety and gut health, if you’re a picky eater who avoids eating many whole fruit and vegetables, then consuming them in juices and smoothies will be more advantageous than not consuming them at all.
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