Vegetable and Fruit Juices

Effects and Mechanisms of Fruit and Vegetable Juices on Cardiovascular Diseases (2017)

Effects on Blood Pressure:

Several studies found that certain fruit and vegetable juices can reduce both systolic blood pressure (SBP) and diastolic blood pressure (DBP). Specific juices shown to have this effect include:

Sweetie fruit juice - decreased SBP and caused a dose-dependent decrease in DBP, likely due to the flavonoids naringin and naritutin
Pomegranate juice - significant reductions in both SBP (p=0.002) and DBP (p=0.038), possibly due to ellagitannins and anthocyanins
Cherry juice - decreased SBP and DBP in healthy volunteers
Beetroot juice - reduced BP, with one study finding a maximum reduction of 10.4 mmHg SBP/8 mmHg DBP approximately 3 hours after ingestion; effect likely due to the high nitrate content
A mixture of fruit and vegetable juice powder - decreased SBP and DBP in pre-hypertensive and hypertensive subjects

A meta-analysis found fruit juice intake reduced DBP by 2.07 mmHg, but did not significantly affect SBP
However, some studies found no significant effect of certain juices on blood pressure, including grapefruit juice, orange juice, apple juice, and low sodium vegetable juice

Effects on Blood Lipids:

Orange juice was found to significantly lower total cholesterol (TC), LDL cholesterol (LDL-C), apo B, and LDL/HDL ratio in one study on subjects with hypercholesterolemia or normal/moderately high cholesterol
An acai berry-based juice blend substantially improved lipid profiles (triglycerides, cholesterol and fractions) in junior hurdlers, likely due to the high polyphenol content
Tomato juice rich in lycopene decreased serum cholesterol and increased adiponectin and triglycerides in healthy subjects
A mixture of fruit/vegetable juice powder decreased HDL-C and apo A in one study on pre-hypertensive and hypertensive people
A juice mixture of komatsuna (a leafy vegetable) and fruit significantly reduced serum TC and LDL-C levels
However, many studies found no significant effects of various fruit and vegetable juices on lipid profiles, including:

Orange juice and pomegranate juice in hypertensive or hypercholesterolemic subjects
Apple juice, cranberry juice, and grape juice in healthy subjects
Fresh carrot juice

Mechanisms of Action:

Antioxidant effects

Pomegranate juice inhibited LDL oxidation and increased serum paraoxonase activity
Orange juice, carrot juice, and juice mixtures increased plasma antioxidant capacity and decreased lipid peroxidation markers
Blackcurrant juice inhibited inflammatory markers in cultured macrophages

Improvement of cardiovascular system aspects

Purple carrot juice and lingonberry juice improved endothelial dysfunction
Cranberry juice had no effect on endothelial function
Grapefruit juice reduced arterial stiffness but not endothelial function
Concord grape juice improved endothelial function and arterial stiffness
Beetroot juice's effects likely due to increasing nitric oxide levels

Inhibition of platelet aggregation

Purple grape juice inhibited whole blood platelet aggregation by 77% vs orange or grapefruit juice, likely due to higher polyphenol content
Pomegranate juice inhibited platelet aggregation in vitro, likely due to ellagitannins
Orange juice decreased whole blood procoagulant activity regardless of polyphenol content

Anti-inflammatory effects

Tomato juice decreased inflammation markers like MCP-1
Mixed fruit/vegetable juices decreased inflammatory cytokines and CRP
However, orange juice and grapefruit juice did not affect inflammatory biomarkers in some studies

Prevention of hyperhomocysteinemia

Several studies found fruit/vegetable juice intake increased serum folate and decreased plasma homocysteine in smokers, hypertensives, and those with hypercholesterolemia or metabolic syndrome

Potential Negative Effects:

Excess consumption of juices with high natural or added sugar content may contribute to weight gain, obesity and diabetes risk by providing extra calories
Possible association found between intake of high-fructose juices and arthritis risk

In summary, this review found that many fruit and vegetable juices, especially pomegranate, cherry, beetroot, and mixed juice products, can have beneficial effects on cardiovascular risk factors like blood pressure and lipid profiles. The effects appear to be mediated by the juices' antioxidant, anti-platelet, anti-inflammatory and hyperhomocysteinemia-preventing properties attributable to their polyphenol, vitamin and nitrate content. However, results were mixed, with some studies finding no significant impacts. Excess juice consumption may also have detrimental effects due to the sugar content. Overall, moderate intake of polyphenol-rich, low-sugar fruit and vegetable juices may be a useful dietary strategy to reduce cardiovascular disease risk, but more research is needed to confirm the effects and elucidate the mechanisms involved.

The use of a commercial vegetable juice as a practical means to increase vegetable intake: A randomized controlled trial (2010)

Methods

We conducted a 12-week, randomized, controlled, parallel-arm study consisting of 3 groups of free-living, healthy volunteers who participated in study visits at the Ragle Human Nutrition Research Center at the University of California, Davis. All subjects received education on the DASH diet and 0, 8 or 16 fluid ounces of vegetable juice daily. Assessments were completed of daily vegetable servings before and after incorporation of vegetable juice and cardiovascular health parameters including blood pressure.

Results

Without the juice, vegetable intake in all groups was lower than the 2005 Dietary Guidelines and DASH diet recommendations. The consumption of the vegetable juice helped participants reach recommended intake. In general, parameters associated with cardiovascular health did not change over time. However, in the vegetable juice intervention groups, subjects who were pre-hypertensive at the start of the study showed a significant decrease in blood pressure during the 12-week intervention period.

Conclusion

Including 1-2 cups of vegetable juice daily was an effective and acceptable way for healthy adults to close the dietary vegetable gap. Increase in daily vegetable intake was associated with a reduction in blood pressure in subjects who were pre-hypertensive at the start of the trial.

Eight fluid ounces of the vegetable juice (V8®; Campbell Soup Company, Camden NJ) provided 50 calories, 0 g of total fat and cholesterol, 480 mg of sodium, 470 mg of potassium, 2 g of protein, 20 mg lycopene, and 10 g of total carbohydrate of which 2 g were dietary fiber, and 8 g of sugars. The juice provided 40% of the Daily Value of Vitamin A from naturally occurring beta-carotene in the vegetables (1000 IUs = 300 micrograms RAEs (Retinol Activity Equivalents)), 120% of Vitamin C, and 4% of calcium and iron.

Juice powder concentrate and systemic blood pressure, progression of coronary artery calcium and antioxidant status in hypertensive subjects: A pilot study (2007)

Because micronutrients from plants may have beneficial cardiovascular effects, the hypothesis that an encapsulated juice powder concentrate might affect several measures of vascular health was tested in free living adults at low cardiovascular risk. Blood pressure, vascular compliance, lipid and antioxidant markers, and serial electron beam tomography (to calculate a coronary artery calcium score as a measure of atherosclerosis burden), were monitored in 51 pre-hypertensive and hypertensive subjects over 2 years. By the end of follow-up, systolic and diastolic blood pressure decreased significantly (−2.4 ± 1.0 mmHg, P < 0.05 and −2.2 ± 0.6 mmHg, P < 0.001), and large artery compliance improved significantly (1.9 ± 0.6 ml mmHg−1 × 100, P < 0.01). The progression of coronary artery calcium score was smaller than expected compared with a historical database (P < 0.001). Laboratory testing showed a significant decrease in homocysteine (P = 0.05), HDL cholesterol (P = 0.025) and Apo A (P = 0.004), as well as a significant increase in β-carotene, folate, Co-Q10 and α-tocopherol (all P < 0.001). The phytonutrient concentrate we utilized induced several favorable modifications of markers of vascular health in the subjects. This study supports the notion that plant nutrients are important components of a heart healthy diet.

Scientific Evidence on the Relationship Between Tomato and Lycopene Consumption, and Antiplatelet Aggregation Effect (2022)

Regarding the evidence on the beneficial effects of tomato products consumption in healthy people, Sesso et al. (32) conducted a prospective cohort study examining the intake of tomato and tomato juice in 27,267 healthy women free of baseline CVD or cancer. Results indicated that those subjects with a weekly consumption equal to or >10 servings of tomato and tomato products had lower concentrations of total triglycerides, low-density lipoprotein (LDL) cholesterol, and glycated hemoglobin (HbA1c), biological markers of cardiovascular risk. Li et al. (33) conducted a study with 25 young women (20–30 years old) who consumed 280 ml of tomato juice per day for 2 months. A significant reduction in plasma cholesterol levels was observed in all women, as well as an increase in the concentration of adiponectin, a hormone with anti-inflammatory and antiatherogenic properties that modulates the synthesis of nitric oxide (essential in endothelial function) and the proliferation of smooth muscle cells (present in blood vessels, among others). In addition, adiponectin protects against LDL oxidation. An in vivo study carried out by Hsu et al. (34) showed that the consumption of tomato paste for 8 weeks contributed to the reduction of plasma concentrations of total and LDL cholesterol, as well as an increase in plasma high-density lipoproteins (HDL) cholesterol and the activity of antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase.

Burton-Freeman et al. (35) suggested that the consumption of tomato products could also attenuate the oxidation of LDL. This beneficial effect was observed in 25 individuals after eating foods with a high fat content. Postprandial oxidative stress was mitigated by the consumption of these tomato derivatives. Similarly, a decrease in lipid peroxidation, as well as an improvement in the general antioxidant status, was observed by García-Alonso et al. (36) in 18 healthy women who consumed tomato juice for 2 weeks. Xaplanteris et al. (37) also reported this effect in 19 individuals who consumed 70 grams of tomato paste during the same period. The results demonstrated a reduction in oxidative stress and an improvement in endothelial function; the latter is essential to maintain an adequate functioning of the cardiovascular system.

Different scientific studies have suggested that lycopene, as main bioactive compound in the tomato, can exert different beneficial physiological effects for improvements in cardiovascular health via platelet aggregation and related vascular mechanisms. For example, Hsiao et al. (38) systematically examined the effects of lycopene in the prevention of platelet aggregation and thrombus formation and proposed two mechanisms of action through the inhibition of the activation of the enzyme phospholipase C and the synthesis of cyclic guanosine monophosphate (GMP-c). Fuentes et al. (39) verified in vitro that tomato product intake with a higher concentration of lycopene increased the inhibition of platelet activity induced by various aggregating agents such as adenosine diphosphate (ADP), collagen, arachidonic acid, and the thrombin receptor activator peptide-6 (TRAP-6).

Several studies additionally support an association between plasma and tissue levels of lycopene and both pre-clinical and clinical cardiovascular outcomes. Kong et al. (40) also suggested a beneficial effect of lycopene in the early stages of development and progression of atherosclerosis, as well as in the thickness of the intima-media layer of the carotid artery, a parameter that allows quantifying the level of arterial thickening in preclinical phases of cardiovascular disease. Müller et al. (41) highlighted the powerful antioxidant activity of lycopene that could protect endothelial cells against oxidative stress and prevent the formation of foam cells in the early development of atheroma plaque. Sawardekar et al. (42) indicated that lycopene can exert an antiplatelet effect. Different concentrations of lycopene (4–12 μmol/L) were able to in vitro significantly reduce platelet aggregation induced by two aggregating agents, ADP, and collagen. This observed effect was comparable to that exerted by one of the best-known antiplatelet drugs, aspirin. The combination of 4 μmol lycopene/L with 140 μmol aspirin/L showed better results than a single dose of 140 μmol aspirin/L. Phang et al. (43) found an inverse association between plasma and tissue levels of lycopene and the incidence of acute coronary disorders, development of early atherosclerosis, and mortality from heart disease. In addition, Thies et al. (44) showed that subjects with higher lycopene concentrations had a lower risk of suffering a myocardial infarction (59%) and showed a significant improvement in HDL functionality enhancing HDL-antiatherogenic properties.

Clinical trials have also supported the potential beneficial cardiovascular effects attributed to lycopene described above. Klipstein-Grobusch et al. (45), Verghese et al. (46), Kim et al. (47), and Riccioni et al. (48) suggested that lycopene may reduce the risk of atherosclerosis, either directly by attenuating LDL oxidation or indirectly by acting on other cardiovascular risk factors, such as cholesterol. Gajendragadkar et al. (49) conducted a study with 72 individuals, half of them healthy and the other half-undergoing drug treatment because of CVD. There was an improvement in endothelial function in those patients with previous pathologies who ingested a daily amount of 7 mg of lycopene for 2 months. Kim et al. (50) also observed a similar improvement among 37 men with a daily intake of 15 mg of lycopene during the same 8-week follow-up period. These effects for lycopene were attributed to the ability of this bioactive to significantly mitigate oxidative stress and reduce systolic blood pressure.

Other authors have reported a decrease in various cardiovascular risk factors after supplementation with tomato extracts and their derivatives. McEwen (51), Rodríguez-Azúa et al. (52), Palomo et al. (53), Fuentes et al. (39), and Yamamoto et al. (54) suggested that supplementation with tomato extracts may have an antiplatelet effect in vitro, in vivo and/or in humans; or even a thrombolytic activity in some tomato variety studied. Both observed activities are very important to avoid the formation of thrombin and, if they have already formed, their dissolution to prevent more serious cardiovascular accidents such as embolisms.

Palomo et al. (25) conducted a pilot study to test whether a tomato pomace extract (by-product) affected platelet aggregation in healthy humans. Tomato pomace extract contains flavonoids as coumaric acid, floridzin, floretin, procyanidin B2, luteolin-7-O-glucoside, kaempferol, and quercetin; as well as nucleosides (adenosine, inosine, and guanosine). The study showed that the daily consumption of 1 g of aqueous extract of tomato pomace for 5 days exerted an inhibitory activity on platelet aggregation.

Protective Effects of Tomato Juice on Mouse Skin Carcinogenesis (2001)

The anticarcinogenic effect of tomato juice, a natural source of antioxidants and other chemopreventive / antimutagenic agents, was studied in a skin carcinogenesis model in mice. The possible mode of action was also investigated. Oral administration of tomato juice afforded protection from development of skin tumour and increased life expectancy which may be attributed to the combined action of a number of chemical compounds with cancer chemopreventive properties present in tomato. The protective role may be associated with a decreased level of lipid peroxides noted in the tomato treated group and modulation of host detoxification enzymes. Exposure to the carcinogen resulted in a depression of the liver enzymes- glutathione-S-transferase (GST), glutathione peroxidase (GPx) and superoxide dismutase (SOD). Oral administration of tomato juice resulted in significant activation of all these enzymes (p<0.001). These results suggest a preventive role of tomato juice during carcinogenesis which is mediated possibly by their modulatory effects on biotransformation enzymes and the detoxification system of the host.

May Protect Against Certain Cancers (healthline)

Due to its high levels of beneficial nutrients and antioxidants, tomato juice has been shown to have anticancer effects in several studies.

A review of 24 studies associated a high intake of tomatoes and tomato products with a significantly reduced risk of prostate cancer.

In a test-tube study, lycopene extract derived from tomato products inhibited the growth of prostate cancer cells and even induced apoptosis, or cell death.

Animal studies also observe that tomato products may have a protective effect against skin cancer.

Mice that were fed red tomato powder for 35 weeks had significantly less skin cancer development after being exposed to UV light than mice on a control diet.

Though these results are promising, more research is needed to understand how tomatoes and products like tomato juice may affect cancer development in humans.

Tomatoes & Lycopene

Tomatoes are a good source of fiber, with about 1.5 grams in an average-sized tomato. 87% of the fiber content is insoluble, in the form of hemicellulose, cellulose, and lignin (Sharma et al, 1995).

Key Vitamins and Minerals in Tomatoes:

Vitamin C: One medium tomato provides about 28% of the Reference Daily Intake (RDI). Vitamin C is an essential nutrient and antioxidant.
Potassium: Potassium is an essential mineral beneficial for blood pressure control and heart disease prevention (Houston, 2011).
Vitamin K1: Also known as phylloquinone, vitamin K is important for blood clotting and bone health (Booth, 2007; Braam et al, 2004).
Folate (Vitamin B9): One of the B vitamins, folate is important for normal tissue growth and cell function. It's particularly important for pregnant women (Scholl & Johnson, 2000; Greenberg et al, 2011).

The main plant compounds in tomatoes are:

Lycopene: A red pigment and antioxidant, lycopene has been studied extensively for its beneficial health effects (Story et al, 2010).
Beta carotene: This antioxidant pigment is converted into vitamin A in the body.
Naringenin: Found in tomato skin, this flavonoid has shown anti-inflammatory and protective effects against diseases in mice studies (Rao et al, 2013).
Chlorogenic acid: A powerful antioxidant compound, chlorogenic acid may help lower blood pressure in people with elevated levels (Watanabe et al, 2006; Kozuma et al, 2005).

Lycopene is found in the highest concentrations in tomato skin (Shi et al, 2008; Cookson et al, 1961). Generally, the redder the tomato, the more lycopene it contains (Martinez-Valverde et al, 2002). Tomato products like ketchup, juice, paste and sauces are the richest dietary sources of lycopene, providing over 80% of dietary lycopene in the U.S. diet (Clinton, 1998; Hendrickson & Maydole, 2006).

On a gram for gram basis, processed tomato products often have much higher lycopene levels than raw tomatoes (Agarwal et al, 2001; Tonucci et al, 1995). Ketchup contains 10-14 mg lycopene per 100 grams compared to only 1-8 mg in a small, fresh tomato (Takeoka et al, 2001). However, ketchup is typically consumed in small amounts. Eating raw tomatoes can more easily increase lycopene intake and avoids ketchup's high sugar content.

Consuming lycopene with a fat source can boost absorption up to four-fold (Unlu et al, 2005). But not everyone absorbs lycopene at the same rate (Diwadkar-Navsariwala et al, 2003). Even though lycopene levels are higher in processed tomato products, consuming fresh, whole tomatoes is still recommended whenever possible.

Health Benefits of Tomatoes: Tomato and tomato product consumption has been linked to improved skin health and lower risk of heart disease and cancer.

Heart Health: Heart disease, including heart attacks and strokes, is the world's most common cause of death. Low blood levels of lycopene and beta-carotene have been linked to increased heart attack and stroke risk in middle-aged men (Karppi et al, 2012; Karppi et al, 2013). Increasing evidence from clinical trials suggests lycopene supplementation may lower LDL (bad) cholesterol levels (Ried & Fakler, 2011).

Clinical studies show tomato products have anti-inflammatory effects and reduce oxidative stress markers (Jacob et al, 2008; Basu & Imrhan, 2006). They protect the inner blood vessel lining and may decrease blood clot risk (Xaplanteris et al, 2012; Lazarus et al, 2004).

Cancer Prevention: Cancer involves the uncontrolled growth of abnormal cells that spread beyond their normal boundaries to other parts of the body. Observational studies have found links between tomato and tomato product intake and reduced prostate, lung and stomach cancer rates (Giovannucci, 1999; Etminan et al, 2004).

The high lycopene content is thought to be responsible, but more high-quality human research is needed to confirm these benefits (Chen et al, 2013; Trejo-Solís et al, 2013; Qui et al, 2013). A study in women found high blood carotenoid levels, which are found abundantly in tomatoes, may protect against breast cancer (Sato et al, 2002; Eliassen et al, 2012).

Skin Health: Tomato-based foods rich in lycopene and other plant compounds may offer protection against sunburn (Stahl et al, 2006; Rizwan et al, 2011). In one study, people ingesting tomato paste with olive oil daily for 10 weeks had 40% fewer sunburns (Stahl et al, 2001).

Commercial Ripening Process: As tomatoes ripen, they produce ethylene gas (Yang & Hoffman, 2002; Alexander & Grierson, 2002). Commercially-grown tomatoes are harvested while still green and immature. To make them red before selling, food companies spray them with artificial ethylene gas. This process can inhibit natural flavor development and result in tasteless tomatoes (Beckles, 2012). Therefore, locally-grown tomatoes that ripen naturally may have better flavor.

The Bottom Line: Tomatoes are healthy, antioxidant-rich, and may reduce the risk of heart disease and cancer. They are especially high in lycopene, a plant compound linked to health benefits like improved heart health, cancer prevention, and sun protection. Tomatoes can be a valuable addition to a nutritious diet.

Characteristics of some representative studies investigating the health effects of tomato juice.