World Thrombosis Day seems a suitable occasion to highlight the beneficial effects of tomato extracts.
The clear jelly surrounding tomato seeds is an unlikely source for substances with a blood thinning effect that protects against thrombosis, but when scientists tested a variety of fruit extracts for their ability to prevent unwanted blood clots, tomatoes proved a clear winner.
Tomato juice inhibited clotting of human blood, as measured by the aggregation of platelets, by 70% compared with 44% for pink grapefruit, 42% for honeydew melon and 33% for strawberry juice.
Initially, this action was thought to relate to the antioxidant red pigment, lycopene, which is concentrated within tomato skins and the pulp. The anti-clotting potential of each fruit tested did not match its antioxidant potential, however, and other lycopene-rich fruits such as mango and nectarine did not have noticeably powerful effects.
Further investigation revealed that the highest activity was associated with the juicy, yellow fluid around the tomato seeds – not the pulp or skin. The active substances were water-soluble and stable after boiling, which might account for some of the beneficial effects of the Mediterranean and DASH diets against hypertension and heart disease.
What platelets do
Platelets are cell fragments (thrombocytes) that regulate the fluidity of blood. They respond to injuries in blood vessel walls – such as micro-tears caused by high blood pressure – and stick to the underlying exposed collagen.
Once activated, platelets lose their smoothness and become spiky. They release chemical signals (cytokines) that attract more platelets, white blood cells and electrically-charged fat globules into the area to plug the gap.
Ideally, the resulting platelet plug is temporary and dissolves away once healing occurs. If platelets and other components of the coagulation system remain over-active, however, fatty plaques can build up to cause hardening and furring up of the arteries (atherosclerosis).
Continued production of the chemical signals also causes other circulating platelets to become over-active, spiky and sticky, and are more likely to cause unwanted blood clots (thrombosis).
Conditions that are associated with over-active platelets include:
- High blood pressure
- Raised cholesterol
- Increasing age
- Unhealthy diet
- Lack of exercise
- Certain drugs (eg oral contraceptives)
These conditions are all associated with an increased risk of atherosclerosis, angina and thrombosis which can lead to heart attack or ischaemic stroke.
In fact, overactive platelets are now recognised as contributing to increased blood pressure, which in turn damages artery walls, leading to more platelet aggregation to create a vicious cycle.
How tomato extracts work
Researchers have discovered that over 35 different substances within tomato extracts have antiplatelet activity and can reduce the tendency towards thrombosis. What’s more, these substances work in several different ways, and involve several different pathways that inhibit platelet aggregation by increasing the activity of antioxidant enzymes and reducing the activity of phospholipid binding proteins.
Importantly, tomato extracts do not work in the same way as aspirin. Aspirin reduces platelet aggregation through one particular pathway, by inhibiting enzymes known as cyclo-oxygenases (COX-1 and COX-2). The response to aspirin is highly variable, however, with between 20% and 30% of people classed as non-responders due to aspirin-resistance syndrome.
As tomato extracts don’t target COX enzymes, they do not have the same side effects associated with aspirin, such as stomach irritation, peptic ulceration and increased bleeding time. Tomato extracts are also likely to be effective in people who do not respond to aspirin.
Another important point is that, unlike when taking aspirin, the effects of tomato on platelet aggregation are readily overcome when needed to mount a physiological response to injury.
What’s the evidence that tomato extracts work?
While eating tomatoes or drinking tomato juice on their own has beneficial antioxidant effects on the circulation, the active antiplatelet ingredients found within the tomato jelly are not released or absorbed rapidly enough to produce a significant acute effect.
Scientists therefore isolated the active components and concentrated them into a patented extract called Fruitflow.
|An initial study, involving 23 volunteers, showed that consuming these tomato extracts significantly inhibited platelet aggregation by 20% at a dose equivalent to concentrate from 6 tomatoes.
The effect was seen within 3 hours, and persisted for 12 hours.
Graph derived from: O’Kennedy et al 2006. Am J Clin Nutr 84(3):570-9.
A follow-up study, involving 90 healthy volunteers, confirmed that tomato extracts reduced platelet aggregation by 21% after 3 hours, compared with inactive placebo, at a dose equivalent to extracts from 6 tomatoes. At a lower dose, equivalent to extracts from 2 tomatoes, platelet aggregation was reduced by 12.7%. The effects were greatest in those with high levels of substances known to increase the risk of abnormal blood clotting (eg homocysteine, C-reactive protein).
Initially, the benefits of taking Fruitflow last for 12-18 hours but, with continued daily use, they provide 24 hour protection. There are no reported side effects, and no disturbance of the normal blood clotting needed to heal a wound. The extracts have not been found to trigger allergies or intolerances, either.
In the largest single Fruitflow study, positive effects were observed in 97% of individuals tested, which compares favourably with single-drug therapies, such as aspirin, which are ineffective in up to 30% of people.
On-going studies suggest that a single dose of Fruitflow is as effective as 75mg aspirin but without the side effects.
Tomato extracts also have the ability to inhibit angiotensin converting enzyme (ACE) to help lower a raised blood pressure. This makes the extracts especially useful for people with hypertension, in whom increased platelet activity plays a key role.
EU Health Claim
The evidence of effectiveness and safety for tomato extracts are compelling enough that the European Food Safety Authority has authorised a claim that Fruitflow: ‘Helps maintain normal platelet aggregation, which contributes to healthy blood flow.’ And, as I know from personal experience, they are extremely hard to convince!
Supplements containing tomato extracts
A number of products now include the patented Fruitflow tomato extracts, and are designed for healthy adults who wish to maintain their cardiovascular health.
NB Many tomato products contain lycopene (which is beneficial in its own right) rather than Fruitflow – check labels to ensure you get the ingredients you are looking for.
| Sirco is the first 100% Pure Fruit Juice drink to contain FruitFlow. Drinking one 250ml serving of Sirco works within 2-3 hours from when you drink it and lasts up to 18 hours.
Check price on Amazon.co.uk
|Swanson Ultra Circulatory Health Formula each supply 1g of Fruiflow extract.
The recommended daily dose is 3 capsules per day, taken together. There is no convincing evidence that doses this high are needed, however.View price on Amazon.co.uk
See price at Amazon.com
Healthspan Circulease provides 150mg Fruiflow extract, plus potassium and vitamins B1, B2 and B12 for their beneficial effects on blood pressure and the circulation.
|Provexis Fruitflow + Omega-3 provides 150mg Fruitflow plus 500mg omega-3 fish oils (150mg EPA and 100mg DHA).
Buy via Fruitflowplus.com
Image credits: Provexis; Blausen.com