Are you wasting your money on performance aids? Discover which products really deliver the goods

Want a supplement that boosts your stamina, speed and strength or eases your recovery time? It seems many of us do, as the range of pills, bars, shakes and powders on the market, all promising enhanced performance, is growing all the time. But are they worth it? Are you wasting your money, or at worst, doing yourself harm? We asked sports nutritionist Anita Bean to sift through the latest scientific evidence and find out what really works.

Beetroot for endurance

Beetroot is a rich source of nitrates. These are converted in the body into nitric oxide, a potent vasodilator (widens blood vessels) that helps increase blood flow and delivery of oxygen and nutrients to muscles. This lowers the amount of oxygen your muscles need to sustain sub-maximal exercise.

Why it works

Several studies with non-elite athletes show nitrate in beetroot juice may help sustain higher levels of power for longer before fatigue sets in. It reduces maximal oxygen uptake, improving exercise economy so you need less energy to do the same amount of work, and allows you to exercise longer. University of Exeter researchers found drinking 500ml of beetroot juice a day for a week enabled volunteers to run 15 per cent longer before experiencing fatigue.

How to take it

To get enough to enhance performance you’d need to eat at least 200g (three to four beetroots) a day, so juice is more convenient. Recent University of Exeter research suggests 600mg nitrate may be optimal, equivalent to 2 x 70ml concentrated beetroot shots, taken around two-and-a-half hours pre-exercise.

Caffeine for power

Caffeine is a drug rather than a nutrient, but it’s often considered to be a supplement because it’s found in everyday foods and drinks, such as coffee, tea, chocolate and energy drinks.

Why it works

Caffeine is a stimulant that acts on your central and peripheral nervous system. It increases levels of ß-endorphins (hormone-like substances) in the brain. These endorphins reduce the perception of fatigue and pain. Caffeine helps increase alertness, concentration and performance, and reduces fatigue. It can also help increase muscle fibre recruitment and boost performance in anaerobic activities. A UK analysis of 40 studies found caffeine significantly improves endurance, on average by 12 per cent (Doherty and Smith, 2004).

How to take it

When taken 30 minutes to three hours before exercise, research shows caffeine enhances performance in sprints, high-intensity activities lasting four to five minutes, intermittent activities such as team sports, and endurance activities. Take caffeine 30–60 minutes before exercise, during your session (if exercising longer than an hour), or during the latter stages as fatigue sets in. Relatively low doses (1–3mg caffeine/kg) are just as effective as higher doses – that’s 70–210mg caffeine (approximately two cups of coffee) for a 70kg person – although it’s more potent when taken in pill or capsule form.

Fish oils for recovery

Fish oil contains the two unsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived from the tissues of oily, cold-water fish such as tuna and salmon.

Why it works

Omega-3 fatty acids are involved in the activation of ‘locally acting hormones’ known as eicosanoids, which control inflammation and immunity. They’re also vital for the structure and fluidity of cell membranes. Supplementation may be a good way to help reduce inflammation, including post-exercise muscle soreness, and improve muscle functioning, blood vessel elasticity and delivery of oxygen to muscles. One study found omega-3s increased blood flow by up to 36 per cent during exercise (Walser et al, 2006).

How to take it

The NHS recommends 450–900mg of the long-chain EPA and DHA a day, which equals two portions of oily fish a week.

Green tea for calorie burn

Green tea extract is a popular ingredient in fat-burning supplements. The active compounds in green tea are a family of polyphenols (catechins) and flavanols, which are potent antioxidants, as well as caffeine.

Why it works

Green tea extract causes a mild increase in calorie burning and fat oxidation, partly due to its caffeine content and partly to its catechins and flavanols. A UK study found people who consumed a green tea supplement 24 hours before exercise burned 17 per cent more fat during a 30-minute cycling test compared with taking a placebo (Venables et al, 2008). If green tea extract can increase the proportion of fat and decrease the proportion of carbohydrate burned, it may be able to prolong endurance.

How to take it

Taking green tea either as a tea or as a supplement in doses of 125–500mg per day may help you burn a few more calories in conjunction with exercise.

Probiotics for immunity

Probiotics are the live microorganisms (bacteria) that live in your gut, crucial for optimal intestinal health, digestion and immunity. They are found in yoghurt and other cultured milk products as well as capsules, tablets and powders.

Why it works

Probiotics work by re-colonising the small intestine and crowding out disease-causing bacteria, strengthening or restoring the balance to the intestinal flora. They may help protect against and reduce symptoms of gastrointestinal and upper respiratory tract infections (URTI). They may also improve intestinal tract health and increase the bioavailability of nutrients. Probiotics have been shown to reduce the incidence of URTI in athletes in winter, and may also reduce gastrointestinal distress often associated with longer bouts of training.

How to take it

Taking probiotics during periods of heavy training or in the two weeks prior to competition may help enhance your immune system. Most studies have used doses of one to 10 billion bacteria a day. ‘Live’ yoghurt (a 125g serving contains around 4 billion bacteria) may be cheaper than capsules.

Glucosamine for injury protection

Glucosamine is found naturally in the body. It is an amino sugar, and a major component of cartilage, which serves as an important cushioning and shock-absorbing material for the joints. It is also one of the main substances in synovial fluid that lubricates and provides nutrients for joint structures.

Why it works

As the body ages, cartilage loses its elasticity and cushioning properties for joints, which may result in stiffness, immobility and pain. Regular exercisers sometimes suffer damaged cartilage as a result of years of repetitive motion. Glucosamine is thought to work by stimulating the cartilage cells to produce proteoglycans (building blocks) that repair joint structures, so supplements may help restore joint function and mobility.

Results of studies have been mixed. One review concluded that glucosamine sulphate may be effective in delaying the progression and improving symptoms of knee osteoarthritis (Poolsup et al, 2005). However, a study of male athletes recovering from acute knee injuries found daily supplementation with 1,500mg glucosamine did not reduce pain or improve mobility (Ostojic et al, 2007).

How to take it

If you suffer from knee osteoarthritis, it may be worth trying glucosamine supplements. Studies have used 500mg three times a day. It may take three to eight weeks to produce noticeable results. It works more effectively when combined with chondroitin sulphate (a complex sugar found in cartilage).