Superfruits, Juice, and Smoothies

TL;DR. "Superfood" has no scientific definition and has been banned as an unsubstantiated health claim on packaging in the EU since 2007. The exotic berries sold under that banner are not better than blackcurrants or blackberries, and the ORAC score their marketing rests on was withdrawn by the USDA as irrelevant to human health. Juicing removes the fibre and the cell structure that made whole fruit good for you, which is why whole fruit intake is associated with lower diabetes risk while fruit juice is associated with higher. Blending keeps the fibre and still destroys the structure, which puts smoothies somewhere in between.

1. What a "superfruit" is

A marketing category. The word "superfood" appeared in food advertising in the early twentieth century, was revived in the 1990s and 2000s, and has no regulatory or scientific definition anywhere.

The EU banned the use of "superfood" on packaging in 2007 under the Nutrition and Health Claims Regulation, unless accompanied by a specific authorised health claim, of which very few exist for fruit. The UK retained the rule after leaving the EU. The word survives in journalism, in retail signage, and in supplement marketing.

The typical superfruit playbook:

1. Identify a fruit from a distant place with an unfamiliar name.
2. Measure its antioxidant capacity in a test tube using the ORAC assay.
3. Publish the number and compare it favourably with blueberries.
4. Sell it as juice, powder, or capsules at a large multiple of the price of local fruit.
5. Add an origin story about a traditional people who use it medicinally.

Step 2 is the fatal one. The USDA maintained an ORAC database until 2012, when it withdrew it entirely, stating that the values had "no relevance to the effects of specific bioactive compounds on human health" and that they were being routinely misused in marketing (Chapter 17). The scores are still quoted a decade later.

2. The main contenders, assessed

The honest comparison. Blackcurrants contain about 180 mg of vitamin C per 100 g and 250 to 500 mg of anthocyanins. Wild blueberries, blackberries, and aronia are all in the same league as the exotic imports on polyphenol content. They cost a fraction as much, arrive fresh or frozen rather than as a powder, and come with fibre and water rather than in a capsule.

There is nothing wrong with açaí bowls or goji berries. There is something wrong with paying ten times the price on the basis of a laboratory score that the agency which published it has disowned.

3. Juice: what removing the fibre does

In short: Juicing discards the fibre and the cell walls, which converts a slow food into a fast one.

A whole orange and a glass of orange juice contain similar sugar. They do not behave similarly.

The classic demonstration is the 1977 Haber study referenced in Chapter 20: the same apples eaten whole, as purée, and as juice produced progressively faster consumption, progressively higher insulin responses, and progressively less satiety, with the juice group showing a rebound dip in blood glucose that the whole-fruit group did not.

The epidemiology is consistent with this. The pooled analysis of three large US cohorts (Muraki and colleagues, BMJ 2013) found that higher whole fruit intake was associated with lower type 2 diabetes risk (blueberries, grapes, and apples/pears most strongly), while higher fruit juice intake was associated with higher risk. Substituting three servings a week of whole fruit for juice was associated with about a 7 percent lower risk.

Where juice is not the villain:

• 100 percent juice is not the same as a sugary soft drink. It carries vitamin C, potassium, folate, and polyphenols that a cola does not, and the associations with harm are weaker than for sugar-sweetened beverages. Several analyses find small or null associations for modest intakes.
• A small glass (150 mL) counts as one portion of the five-a-day in UK guidance, and only one, however much you drink, precisely because of the fibre issue.
• Orange juice with a meal substantially increases iron absorption from plant foods (Chapter 16).
• Juice is genuinely useful for people who struggle to eat: after surgery, during illness, in frail older adults, and for hypoglycaemia treatment where fast sugar is exactly what is needed.

Where juice is worse than it looks:

• Children. The American Academy of Pediatrics recommends no fruit juice at all under 12 months, no more than 120 mL a day for ages 1 to 3, and 120 to 180 mL for ages 4 to 6. Excess juice in toddlers causes poor weight gain (juice displaces food), chronic diarrhoea (from sorbitol and fructose, particularly apple and pear juice), and dental caries. This is one of the most consistently recommended and most widely ignored pieces of paediatric nutrition advice.
• Teeth. Fruit juice is acidic and sugary, and sipping it through the day is among the more reliable ways to erode enamel.
• Cold-pressed and unpasteurised juice carries a real food safety risk. The 1996 Odwalla E. coli O157:H7 outbreak in unpasteurised apple juice caused 66 illnesses and a child's death and drove US regulation requiring either pasteurisation or a warning label. Pregnant, immunocompromised, elderly, and very young people should not drink unpasteurised juice.
• "Not from concentrate" versus "from concentrate" is a difference in processing and transport, not in nutritional value. Both are pasteurised. NFC juice is often stored in vast deaerated tanks for months and has flavour packs added back, which is legal and undisclosed.

Juice cleanses and detoxes deserve a plain statement: your liver and kidneys detoxify continuously and do not need assistance. No juice cleanse has been shown to remove any named toxin from the body. What they do reliably produce is a low-calorie, low-protein, high-sugar few days, with headaches and hunger, followed by regained weight. In people with kidney disease or diabetes they can be actively dangerous, and several cases of oxalate nephropathy have been reported after aggressive juice cleanses heavy in spinach, beetroot, and other high-oxalate greens (Chapter 18).

4. Smoothies: better than juice, worse than fruit

In short: Blending keeps the fibre but destroys the physical structure, which puts smoothies about halfway between whole fruit and juice.

A blender does not remove anything. All the fibre is still present, which is a real advantage over juicing. What it does is reduce particle size to a point where the cell walls no longer slow digestion much (Chapter 11).

Studies comparing whole fruit, chopped fruit, and blended fruit generally find intermediate glucose responses for the blended version and lower satiety than whole fruit at the same calories. A 2020 study found that smoothie blending of berries increased the glycaemic response compared with the whole berries, largely by breaking the seeds and cell walls.

Making a smoothie better:

• Add protein and fat: yoghurt, milk, kefir, silken tofu, nut butter, seeds. This flattens the glucose curve and adds substantial satiety.
• Weight it toward vegetables: spinach, kale, cucumber, courgette, and avocado add volume and nutrients with almost no sugar.
• Limit the fruit. Two portions is plenty; a large fruit smoothie can easily contain four to five portions and 40 to 60 g of sugar.
• Do not use juice as the liquid. Water, milk, or plant milk instead.
• Blend less. A coarser blend retains more structure.
• Include some frozen fruit, which improves texture without ice and is nutritionally equivalent or better (Chapter 9).
• Rotate the greens if you make green smoothies daily, because large habitual quantities of a single high-oxalate green (spinach, chard, beet greens) are a genuine kidney risk.

5. Fruit powders, extracts, and capsules

The general problem: a powder concentrates the compound whose relevance is uncertain, discards the water and much of the fibre, and is sold at a large premium.

Specific cautions worth knowing:

• Green tea extract capsules have caused liver injury, sometimes severe, and are among the most frequently implicated supplements in drug-induced liver injury registries. Drinking green tea does not carry this risk; the concentrated extract does.
• Grapefruit and pomegranate extracts retain the CYP3A4 inhibition of the fruit (Chapter 22).
• Goji and cranberry extracts have both been associated with raised INR in people taking warfarin.
• Bitter orange (synephrine) extracts sold for weight loss have a cardiovascular safety signal and were adopted by the supplement industry after ephedra was banned.
• Supplement regulation is far looser than food or drug regulation, in both the US and UK, with no pre-market approval of efficacy and limited enforcement of contents (Chapter 81). Independent testing repeatedly finds products that do not contain what the label says.

6. What the evidence actually shows

Established: whole fruit intake is associated with lower risk of type 2 diabetes, cardiovascular disease, and total mortality. Fruit juice is associated with higher diabetes risk in the same cohorts. ORAC scores do not predict human outcomes.

Strong: the paediatric case against fruit juice for young children. The general principle that physical structure of food changes its metabolic effect.

Mixed: whether modest amounts of 100 percent juice (a small daily glass) do net harm in adults, where evidence is genuinely equivocal and the effect, if any, is small.

Thin to absent: every specific superfruit claim in this chapter, detox and cleanse protocols of every kind, and fruit powders as a substitute for fruit.

7. What to do instead

1. Eat fruit whole. This is the entire chapter in three words.
2. Buy local and seasonal, and frozen out of season. Frozen berries are nutritionally equal or better than fresh imports and cost far less.
3. If you want polyphenols, blackcurrants, blackberries, aronia, wild blueberries, red cabbage, and dark grapes deliver as much as anything flown in as powder.
4. Limit juice to a small glass, ideally with a meal, ideally not for children.
5. Make smoothies with protein, fat, and vegetables, and treat them as a meal rather than a drink.
6. Ignore ORAC scores and the word superfood. Both are marketing artefacts.
7. Treat concentrated extracts as drugs. They interact, they can damage the liver, and they are not regulated as medicines.

8. The bottom line

• "Superfood" has no definition and is banned on EU packaging. The exotic berries sold under it are not better than blackcurrants, and the ORAC score behind the whole category was withdrawn by the USDA as irrelevant to human health.
• Juicing removes the fibre and the cell structure. Whole fruit intake is associated with lower diabetes risk; juice with higher, in the same cohorts.
• Juice has legitimate uses: with a meal to boost iron absorption, for people who cannot eat, and for treating hypoglycaemia. It should be limited in children and it should not be sipped through the day.
• Smoothies retain the fibre and lose the structure, which puts them in between. Adding protein, fat, and vegetables makes them substantially better.
• Detox and cleanse protocols do not remove toxins, and aggressive green juicing has caused kidney injury.

Sources and notes

The EU ban on unsubstantiated "superfood" claims follows Regulation (EC) 1924/2006 on nutrition and health claims. USDA's withdrawal of the ORAC database, with its stated reasoning about irrelevance to human health and misuse in marketing, was announced in 2012. Acai marketing enforcement follows US Federal Trade Commission actions from 2010 onward. Goji and warfarin interaction follows published case reports. Noni hepatotoxicity follows EFSA's review of case reports. Camu camu, baobab, and aronia composition figures are from published analyses and USDA data. The whole fruit versus juice diabetes comparison is Muraki et al., BMJ, 2013. The whole-versus-puree-versus-juice satiety and insulin comparison is Haber et al., The Lancet, 1977. Paediatric juice guidance follows the American Academy of Pediatrics policy statement, Heyman and Abrams, Pediatrics, 2017. The Odwalla E. coli O157:H7 outbreak of 1996 and the resulting US juice HACCP rule are documented by the FDA. Blended fruit and glycaemic response follows comparative trials on berry smoothies. Green tea extract hepatotoxicity follows EFSA's 2018 assessment and the LiverTox database. Oxalate nephropathy after juice cleanses follows nephrology case reports.

Open questions. Whether modest daily 100 percent juice consumption in adults does net harm is genuinely equivocal, with different large cohorts pointing in different directions. Most superfruit claims have never been tested in humans at all, so "no evidence" here means untested rather than refuted.

👉 That completes the fruit. Next, the vegetables, starting with what a vegetable actually is and what cooking does to it.