Functional drinks: Health benefits or fad?

The rise of functional drinks
Functional drinks represent one of the fastest-growing segments within the broader functional foods market. Their expansion reflects increasing consumer interest in products that not only provide hydration, but also offer potential benefits for overall health, performance, and long-term disease risk reduction. But do the offer real promise and are they risk free?

What are functional drinks
A functional drink is typically defined as any non-alcoholic drink that confers additional physiological benefits beyond basic nutrition due to the presence of bioactive compounds derived from plant, animal, marine, or microbial sources ⁽¹⁾. These drinks are commonly grouped into dairy-based, plant-based, and sports or energy drinks. They sit within the wider category of functional drinks, which encompasses drinks designed to support specific aspects of health or wellbeing, either through intrinsic properties or through the addition of bioactive ingredients. Common raw materials include plant-derived milks (such as soy, oat, rice, coconut, and nut-based drinks), fruit and vegetable juices, dairy products, herbal infusions, and formulations containing prebiotics, probiotics, or synbiotics. Fruits and vegetables are particularly valuable, contributing hydration alongside fibre, micronutrients, and a diverse range of phytochemicals. Consumer demand is driven by several converging factors: greater awareness of the relationship between diet and health, increasingly time-pressured lifestyles, and the convenience of ready-to-consume products. Interest in complementary and preventive health strategies has also contributed, particularly in the context of chronic disease management ⁽¹⁾.

Key ingredients and purported health benefits
Functional drinks often contain bioactive compounds such as polyphenols, vitamins, minerals, amino acids, unsaturated fatty acids, and bioactive peptides. These compounds, derived from microbial, plant, or animal sources ⁽¹⁾, are associated with antioxidant, anti-inflammatory, and metabolic effects. Emerging evidence suggests potential roles in supporting cardiovascular health, glycaemic regulation, immune function, and cognitive performance ⁽⁷⁾. However, while mechanistic and observational data are promising, the strength of clinical evidence varies, and effects are often modest and context-dependent.

Functional drinks and digestive health
Fermented drinks are among the fastest-growing categories within this sector. They offer advantages such as relatively low cost, extended shelf life, and preservation of sensory qualities, while also being positioned as beneficial for digestive health ⁽⁴⁾. These effects are largely attributed to their content of probiotics and prebiotics. Probiotics are live microorganisms that, when consumed in adequate amounts, may confer health benefits, while prebiotics are substrates selectively utilised by beneficial gut microbes. Synbiotics, which are combinations of both, aim to enhance these effects. Proposed mechanisms include improved gut barrier integrity, modulation of immune responses, production of short-chain fatty acids, and competitive inhibition of pathogenic organisms. Postbiotics, metabolic byproducts of microbial fermentation such as organic acids and peptides are gaining interest as they may offer similar benefits with fewer safety concerns ⁽⁴⁾. While many traditional probiotic drinks are dairy-based (e.g. yogurt drinks or kefir), non-dairy alternatives are increasingly available, including fermented fruit juices and plant-based substrates. This is particularly relevant for individuals with lactose intolerance or dairy sensitivities. It is important to note that probiotic use is not without potential risks, particularly in vulnerable populations, and variability in strains, dosages, and formulations complicates the interpretation of outcomes and risks of interactions with certain medications and gastrointestinal conditions ⁽⁴⁾.

Energy, hydration, teengers
Energy drinks are a prominent subset of functional drinks, typically containing caffeine, sugars, B vitamins, and compounds such as taurine. Their primary effects on alertness and performance ⁽⁵⁾ are largely attributable to caffeine and carbohydrate content. However, formulations vary widely, and the combined effects of ingredients are not always well studied. Regular consumption of high-sugar energy drinks may contribute to weight gain and adverse metabolic outcomes. Even lower-sugar or “clean-label” alternatives should be approached cautiously, particularly in adolescents, pregnant or lactating women, and individuals with cardiovascular or metabolic conditions, as consumption of over the counter energy drinks in teenagers have ben linked to mood changes, anxiety and cardiometabolic risks, with the UK Government considering restricting energy drinks for adolescents under 16 years of age ⁽⁸⁾.

Challenges and considerations
Ongoing research is focused on improving the stability, delivery, and bioavailability of functional ingredients through techniques such as encapsulation and emulsification. While these innovations may enhance product performance, their implications for safety, efficacy, and environmental sustainability require further evaluation. There is also increasing interest in utilising food by-products, such as fruit pomace, as sources of bioactive compounds, which may improve sustainability. Similarly, non-nutritive sweeteners like stevia are being explored to reduce sugar content, although their broader metabolic effects remain an area of active research ⁽³⁾. A key limitation in the field is the lack of standardisation, particularly for probiotic products, making it difficult to compare studies and draw firm conclusions ⁽⁴⁾. In addition, regulatory oversight and accurate labelling are essential to ensure that health claims are evidence-based and not misleading ⁽²⁾.

Future trends
The category continues to evolve, with innovations including enzyme-treated fruit drinks, novel plant sources, and emerging technologies such as nano-formulations. Some products are even redefining traditional concepts of drinks, blurring the line between food, supplement, and sensory experience.

Conclusions
Functional drinks offer a convenient means of delivering bioactive compounds and may contribute to health when incorporated into a balanced lifestyle. However, they are not a substitute for a nutrient-dense diet, regular physical activity, and other foundational health behaviours. Continued research is needed to clarify optimal formulations, long-term safety, and clinically meaningful outcomes in human populations ⁽⁶⁾.