Smoothies vs. Juicing: Which is the better Diet Drink?
You have read about them. You have probably tried one of them; perhaps both drinks, by now. Smoothies are those creamy delights that add just the right amount of fruit and prebiotic ingredient, limited carbohydrate and fat into a flavored drink. Juicing is watery beverage often served cold and built on either a fruit or a vegetable base with limited carbohydrate and fat mixture.
So, what is the difference, other than creamy and water-based consistencies that make one the better diet drink? Is it the ingredients? Is it the bioavailability for digestion? Maybe it’s the ingredients that make the texture in the drink base! This presentation will present research using the hypothesis that either smoothies or juicing is the better diet drink.
A smoothie is traditionally only made with fruit, not vegetables.
In its purest form, the fruit smoothie is a 100-percent blend of fruits, not a concentrate, and devoid of added sugar or additives. The fruit of a smoothie is whole and thus includes the pulp, fiber and flesh (Agbenorhevi and Marshall, 2012). In contrast, juicing is comprised of either fruits or vegetables (Keane, 1992). As such, the variety of vitamins varies by the vegetables chosen for the juicing.
Blacker, Creanor & Creanor (2011) studied four commercially available fruit smoothie products for pH and acidity levels since each was based on a 100% fruit juice consistency. Each of the fruit smoothies was found to maintain a low or acidic pH with a relatively high amount of buffering agent, sodium hydroxide (NaOH), needed to reach stability of the acidity. The researchers concluded that the drinks are best consumed by limiting intake with a straw and taking the product during a regular meal. The regular meal would assist buffering the acidic qualities of the drinks. Conversely, calcium carbonate such as antacids or sodium bicarbonate products such as baking soda can be used in limited amounts for a short duration.
Whisner et al. (2013) studied galacto-oligosaccharides, the medical term for smoothies since they are prebiotic agents that increase calcium absorption. It was already known the value of galacto-oligosaccharides for post-menopausal women, but this study focused on bone growth in adolescent girls of 10-13 years. The 31 study subjects consumed smoothies twice a day over a 3-week period using random ordering of 0, 2.5 and 5 grams of galacto-oligosaccharides. Microbiota and Bifidobacteria were tested in the girls’ feces and contrasted against urine calcium levels to confirm calcium absorption levels. The findings of the study pointed to the daily consumption of 5 grams of smoothie drink to increase calcium absorption. The researchers pointed to the interactions in the intestinal microbiota, specifically Bifidobacteria, which contributed to calcium absorption from drinking smoothies.
Blacker and Chadwick (2013) researched fruit smoothies for the erosive potential on dentition. The purpose of the study was to balance the recent surge of smoothie and juicing activity in the face of health commission campaigns promoting at least five portions of fruit and vegetables per day. The study selected five well-known fruit smoothie brands, including one marketed as a “thickie.” These were then compared to water (Volvic™), orange juice, and a homemade smoothie as control drinks. The homemade smoothie was based on the very recipe as was described in one of the commercially-prepared drinks.
According to the researchers, critical pH for protecting dental enamel from erosion is 5.5. Only two of the commercial drinks were above critical pH to protect the dental enamel from erosion, which included the “thickie,” which used a yogurt, vanilla, and honey base. The homemade smoothie that used the commercial recipe was equally erosive to dental enamel. The researchers recommended, based on the findings and limitations of the study, when individuals depend on smoothies for their daily portions of fruit they should drink only during mealtimes. Clearly, brushing teeth immediately after smoothie use is an alternate suggested recommendation.
In a related UK study, dentition was compared by specific fruits to citric acid by Ali and Tahmassebi (2014). While citric acid has a pH of 2.61, the mango and passion fruit smoothie had a pH of only 3.9. Still, the most acidic were the Innocent® blackberries, strawberries, and blackcurrant smoothies. These are all below the 5.5 critical pH for protecting dental enamel. The researchers also cited the banana smoothie as having sufficiently low pH to cause dental erosion.
Whisner and Weaver (2013) researched galacto-oligosaccharides or fruit smoothies for their much-needed calcium benefit. Society received the clear message that excessive intake of carbohydrates, both simple and complex, was unwise. Unfortunately, 52% of American adolescents studied in 2005-2006 abandoned dairy products with cereals and lost the vital source for calcium and vitamin D. This is most important for adolescents when 90% of bone mass is accumulated. Research has identified that insufficient bone mass storage during adolescence sets the stage for osteoporosis later in life. The researchers noted galacto-oligosaccharides with their prebiotic, non-digestible carbohydrate components, resolves the needed source of calcium in the adolescent diet while introducing necessary daily, dietary fruit portions. Galacto-oligosaccharides have been found to absorb calcium readily into the intestines as well as decrease calcium removal from existing bone. This results in overall bone mass and strength.
Agbenorhevi and Marshall (2012) explored the total phenols and antioxidant activity of three different fruit smoothies (Blackberries, Raspberry and Boysenberry) with the blackcurrant, acerola cherry, rose hips, mango, and passion fruit juices. Total phenols provide the bulk of antioxidant activity in non-citrus juices. Blackcurrant, acerola cherry, and rose hips were found to have the highest total phenols and antioxidant activity. However, the juices were unable to retain their phenolic and antioxidant qualities on the shelf. While the level of antioxidants was found to be less in the fruit smoothies the level remained constant during storage. This suggests that the smoothie is a more resilient vehicle to retain antioxidant activity.
Zhou and Zhang (2008) were interested in the juicing benefits of rice milk. The researchers desired to combine the benefits of calcium with fiber and rice enzymes. This follows the current mantra of adding five portions, each, of fruits and vegetables to the daily diet. Additionally, growing evidence shows diet contributes 35% towards combating at least ten known cancers and is the single, most effective tool (Keane, 1992). Juicing, according to Keane (1992), contributes the bulk of this benefit through the wider variety of antioxidants, vitamins and minerals because it uses vegetables, not just fruit. And, both fruit and vegetable daily portions can be easily satisfied through the practice of juicing (Blauer, 1989). The text likens eating five pounds of carrots to drinking two to four glasses per day of the homemade equivalent of an eight-vegetable juice.
Nelson (2014) from the Mayo Clinic opines that eating fresh fruit and vegetables is just as effective as getting the same items from juicing. The vitamins, minerals, and antioxidants are salvaged from the fruits and vegetables in the juicing devices, which is a positive finding. However, the drawback from juicing is the most valuable dietary benefit; the fruit and vegetable fiber, is usually discarded as waste. Unless the user has a device that shreds the fiber into the juice, opines Nelson (2014), it is more beneficial to just eating the whole fruit and vegetable as part of the meal. Clearly, the juices, skins, and other nutritious parts of the plant would need to be salvaged and eaten.
George, Paterson, Waroonphan, Gordon & Lovegrove (2012) explored the benefits of high fruit and vegetable diets on individuals at risk for coronary vascular disease (CVD). The hypothesis or theory was that the phytochemicals in fruits and vegetables may lend protection to this subset of the population. Since there are many variations in presentation of such phytochemicals the researchers limited their study to only pureed fruits and vegetables, which are essentially juiced. Researchers evaluated vasodilation or blood pressure responses to phytochemical bioavailability, antioxidant levels, and study subjects’ CVD risk factors.
There were two, 6-week cycles to evaluate 39 study subjects of unknown gender with an 8-week “washout” separation between each cycle so the randomized group could not know who was getting a placebo. Those study subjects who received the pureed or juiced fruit and vegetables demonstrated significant increases of plasma α- and β-carotene along the endothelial (inner arterial wall) lining, which stimulated vasodilation or increased space. The details remained sketchy about the exact puree juicing ingredients or whether the whole fiber content was included.
Blanch, Clifton, and Keogh (2015) investigated the findings of George, Paterson, Waroonphan, Gordon & Lovegrove (2012) and compared endothelial or inner arterial wall lining function research using meta-analysis. A meta-analysis of the effect of potassium, fruits and vegetables on vascular function included comparing research from Medline, Embase, and even the entire Cochrane Library. Potassium, alone, according to Blanch, Clifton, and Keogh (2015) conferred some benefit in doses exceeding 40 mmol/day, but the mechanism remained a mystery and the dangers of stopping the heartbeat in certain individuals remained real. The finding of increased benefit from fruits and vegetables was found to help possibly only those individuals found to have a high risk for cardiac risk.
Ishida, Roberts, Chapman and Burri (2007) researched lycopene, a powerful biological antioxidant found in fruits and vegetables. Tangerine tomatoes have been found to have high cis- and trans-isomers or left and left-right handed forms of the same molecular structure. Researchers demonstrated a pronounced decrease in lycopene bioavailability when tangerine tomatoes are mechanically processed by juicing. Lycopene has been found to prevent prostate cancer when eaten in the diet (Burri et al., 2009).
Verma et al. (2013) note the once popular nutraceutical diet from India, drinking fruits and vegetables, has now reached the Western diet. However, Vanhanen and Savage (2015) observe the excessive consumption of vegetable and fruit through juicing has released disproportionate levels of oxalate from nutraceuticals. Oxalate is a major contributor to kidney stone formation. The researchers contrasted population studies between the ranges of 1964-1972 before juicing became popular and 1988-1994 when juicing became mainstream. The researchers calculated that of those who practiced juicing had now doubled their risk of kidney stone formation. The lifetime risk of kidney stone formation by oxalate accumulation only is now 15% in men and 6% in women.
Smoothies appear to have benefits adding digestive enzymes in the colon and adding much-needed dietary fiber from whole fruit. Calcium has marked benefit for the adolescent smoothie community that researchers herald. Researchers note smoothies are remarkably stable for holding antioxidant, but not phenolic compounds in storage. The marked acid levels make smoothies a difficult beverage to drink alone and thus the fruit smoothie is best relegated to meals unless buffered with a temporary antacid and followed with brushing teeth.
Then, the juicing option appears to have benefits because it combines vegetables into the blend.
Depending on the selection of vegetable or vegetables the antioxidants, phenolic compounds, vitamins, and minerals can be quite beneficial. Research supports carrots, tomatoes, and green leafy vegetables. The choices are largely what the individual throws into the juicer. The benefit can vary greatly from day to day. Still, most of the fiber is discarded and lost as a true benefit. Also, risks from oxalate formation in the kidney are doubled according to researchers in contrast to eating the fruits and vegetables whole.
So, which is better, smoothies or juicing? Maybe it depends on the individual. If the individual is an adolescent and they are assured of brushing their teeth after each use, the smoothie may be the better option. If the individual has a high cancer or coronary vascular disease (CVD) risk, maybe the juicing option is the better option. Ultimately, it appears a mixture of both choices is the best option since the bottom line is to increase intake of daily fruit and vegetables to five portions, each!
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