Q: Can a three-day juice fast really detox your body?
The straight answer: No
Fans of juice fasting claim that drinking fresh fruit and vegetable juices for three days is the trick to giving the body a good spring clean. As fresh juices contain high amounts of vitamins and minerals, they help detoxify the body from the inside, encouraging the organs to expel toxins and remove waste products from the bloodstream.
During the "cleanse", nothing but fresh-pressed, organic juices and water can be consumed. Green vegetables are said to be especially purifying, because they are rich in chlorophyll. The juices have to be drunk very slowly to maximise the absorption of nutrients, and chewing is recommended to help stimulate the production of saliva, which contains digestive enzymes.
As poisons are purged from the body, juicing devotees rave about the other supposed benefits of the detox: improved stamina, since the energy that would otherwise have been used to digest food is conserved, a clearer complexion, thanks to the increased vitamin and mineral intake, and weight loss.
The human body produces, ingests or inhales toxins every day, in the form of environmental pollutants, like second-hand smoke and car exhaust, pesticides, food additives, toxic metals (that is, mercury from fish), and bisphenol A from plastic drink containers.
The thing is a juice cleanse is not necessary because our systems are already equipped to remove these poisons naturally. Dr David Tjiu, specialist in general surgery at Matilda International Hospital, says our respiratory system ensures that excess carbon dioxide is expelled through the breathing process. Our liver and kidneys, which make up our renal and hepatobiliary systems, excrete toxins, such as alcohol, through the urine and faeces. Our gastrointestinal system prevents toxins from accumulating in the body. Diarrhoea is a natural process by which these negative presences are flushed from our system.
Sally Poon Shi-Po, a registered dietitian at Personal Dietitian, says there is little scientific evidence to support the cleansing or detoxifying powers of juice.
"Our digestive system is already very good at eliminating toxins, and a good way to boost the efficacy of the gastrointestinal tract is to increase your fibre and water intake and consume yogurt or probiotics."
A three-day juice fast will likely not cause serious harm. In fact, says Poon, it may even motivate a person to make positive dietary changes, such as eating more fruits and vegetables. However, it is important to note that such cleanses should not last for prolonged periods, as it can lead to nutrient deficiencies.
Some juices can actually have detrimental side effects. Raymond Chung Tsz-man, a nutritionist at Albert Place Practice/Mineralysis, says grapefruit and hawthorn berry juices can induce a state of low blood pressure and should not be taken by those who already suffer from the condition.
Another concern is the interaction between certain juices and drugs. Cleansing concoctions containing grapefruit juice, for example, can be very dangerous if consumed with some Western medicines and Chinese herbs, because grapefruit can alter their action or absorption. As juices contain high amounts of potassium, they are also not recommended for people suffering from kidney failure or renal insufficiency.
People with diabetes or low blood sugar, growing children, teens, pregnant women, and older adults should avoid the juice cleansing diet.
"If you want to go on a cleanse or a diet for a specific therapeutic purpose, it is best to consult a health care professional first," Chung says.
"And it's important to remember that detoxification takes time - usually longer than three days - because most chemicals are accumulated in our fat cells or bind to protein in our organs."