Could Boosted Fruit Smoothies Really Help Weight-loss, Improve Memory And Prevent Infections?

This month, UK supermarkets will begin to sell a new range of fruit smoothies 'boosted' with ingredients that are said to assist weight-loss, protect the endothelium, relieve mental fatigue, improve recall, and prevent infections in elderly people and children. At £1.79 ($3.55) for 250ml they cost about the same or less than regular fruit smoothies and they have been specially formulated to meet the taste and texture requirements that emerged from extensive consumer research. But people who are induced to buy these drinks to remedy a health problem may first want to know if boosted smoothies are really likely to deliver what they suggest on the label and whether or not they are safe.

Claims for the healing powers of specific foods are often to be taken with a metaphorical pinch of salt. As a recent TV documentary highlighted, many claims that hit the headlines are based on scant evidence, often touted by a marketing board associated with the foodstuff. Contradictory studies cause confusion when excessive amounts of some products are later associated with harm, for example, most recently, consumption of more than 7 eggs per week.

The difference with the new boosted smoothie range is that the manufacturer, Nestlé, has a proven record of scientific credibility and runs the world's largest food and nutrition research centre, based in Lausanne, Switzerland. The company, which wants to be seen "not just as a trusted food company but as a respected nutrition and wellness company also", says it has carefully researched the safety, health and mental performance benefits of ingredients it is putting in these products and has evidence to support them.

So what is the difference between 'boosted' and ordinary smoothies? The basic content of both is a mixture of pureed fruit and juice, both high in vitamin C and anti-oxidants that have been linked to cardiovascular benefits. A single 250ml bottle counts as one of the recommended five-a-day fruit and veg intakes. But 'boosted' smoothies come with a difference that makes them effectively functional foods - ie, foods with added ingredients that give them health benefits beyond those of their natural nutrient content. These should not be confused with 'super' foods such as oily fish, oats, tomatoes, broccoli, watercress, blueberries and walnuts which have been linked to specific benefits in helping to prevent or control disease; nothing is added to super foods to provide their health benefits. Functional foods on the other hand have been supplemented with additive ingredients, traditionally vitamins and minerals, to prevent nutritional deficiency diseases. 'Boosted' fruit smoothies hope to offer greater health benefits with the addition of specific phytophenols, a probiotic and a catechin - an extract from green tea.

The first four boosted smoothies include an 'energy' boost, a 'mind' boost, an 'immunity' boost and a 'metabolism' boost. A 'heart' boost is also planned. 'Mango mania', the energy boost drink, contains in addition to fruit, 200mg Panax ginseng extract and 75mg guarana extract. 'Smashin Strawberry' the mind boost drink contains a higher, 500mg, amount of Panax ginseng along with 75mg of guarana. 'Berry Blitz' the immunity boost contains Lactobacillus paracasei ST11, a unique non-dairy probiotic strain, while 'Tropical Twist' the metabolism boost contains a green tea extract called epigallocatechin gallate (EGCg).

What's the evidence?

The smoothie range itself has not yet been subjected to randomised double-blind placebo-controlled clinical trials but the individual ingredients have been; several experts believe the evidence for them is sound.

Dr David Kennedy, Director of the Brain, Performance and Nutrition Research Centre at Northumbria University has conducted placebo-controlled trials involving single doses of Panax ginseng looking at effects on short-term memory, information retrieval (recall), attention, concentration and mood. "We found a single dose had a significant effect in eliciting a faster response to stimuli. Panax ginseng reduced mental fatigue, improved the speed of mental processing, and enhanced cognitive performance especially when carrying out complex tasks," he said. Results with Panax ginseng proved more effective than those of gingko biloba, another substance said to improve memory, in similar studies, he added.

Dr Kennedy has also conducted dose-ranging studies of guarana, an Amazonian plant used primarily as a stimulant. Although the plant contains some caffeine he found the 75mg dose, equivalent to a less-than-psycho-active caffeine dose, was most effective. Studies of both Panax ginseng and guarana improved attention, secondary memory (recall) and the speed of memory tasks, he reported. His findings confirm those of similar recently published studies.

Gary Williams, Professor of Functional Foods at Leeds University says the benefits of polyphenols derived from plants have been studied in around 200 human intervention studies. Most show an anti-inflammatory effect translating to a reduced risk of cardiovascular disease. Isoflavones have been shown to improve bone density and catechins to influence fat oxidation. "Polyphenols interact at a number of sites, such as the endothelium, lipoproteins and platelets, in a subtle way over a long period of time," he explained. "There are as yet no recommended daily intakes but to reach a toxic level would require ingesting extremely large quantities so dietary amounts are not a problem." He has a paper in press exploring how polyphenols may reduce the risk of chronic diseases and improve the chances of individuals achieving their maximum potential lifespan.

Studies of epigallocatechin gallate (EGCg).a polyphenol also known as Teavigo, unique to green tea, and included in the metabolism boost drink, have been reviewed by Professor Williamson. "Seventeen studies show it has effects on fat oxidation and energy metabolism, protecting tissue against oxidative stress and chronic disease," he noted. "With regard to weight management, it reduces visceral and abdominal fat by a small but significant amount." A placebo controlled study of human volunteers taking Teavigo for 12 weeks showed a 36 per cent difference in fat oxidation favouring Teavigo, he added. The substance subtly affects cell-signalling theoretically decreasing the risk of carcinogeness and CVD, he added.

Non-dairy probiotic boosts immunity

With regard to the immunity boost drink containing a probiotic, Nestlé's own senior immunologist Dr Jalil Benyacoub has reviewed the extensive evidence. "Probiotics prime the intestinal mucosal immune system, preventing the adherence of pathogens and providing a host of well-recognised benefits," he explained. "These are not just in maintaining gastro-intestinal health, preventing respiratory infections and allergies, but also in reducing inflammatory skin conditions." Nestle has a long interest in probiotics in connection with its research into the benefits of breast milk over formula in helping reduce infants' susceptibility to infections, he pointed out. The company has cultured bacteria for over 30 years and tested more than 3,500 for safety, efficacy and stability. "Lactobacillus paracasei ST11 met all the criteria for development in a liquid drink. It is very stable, has been studed in different populations and has no side effects," he explained. One study, investigating its role in managing non-rotavirus diarrhoea in children, has been rated by the EU as one of the best 25 interventional studies in a common public health problem. In elderly adults it has demonstrated ability to reduce their number of respiratory infections; and in hayfever sufferers it has been shown to significantly suppress nasal allergy symptoms and improve quality of life.

Functional foods may play an important role in the near future when individuals can increasingly expected to be assessed personally for their disease risks, says food chemist Professor Bruce German of University of California. "A personalised nutritional assessment and appropriate advice on tailoring diet and lifestyle to address risks may become a routine part of individual health care," he predicted. Directing patients to suitable tried and tested functional foods as part of a healthy diet to help minimise risks may help people achieve their maximal potential lifespan. Boosted smoothies, yoghurts that lower blood pressure, spreads that lower cholesterol and others are already here. Knowledge-rich consumers wanting to enhance athletic and cognitive performance and delay ageing will spur the development of more functional foods, he suggested. "But these will also have to taste good. It's no good launching functional foods if people have to hold their nose when they swallow them."

Written by - Olwen Glynn Owen
Olwen(at)macline.co.uk
Copyright: Medical News Today
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