Grapes And Their Neuroprotective Properties

Overview

Our nervous system and its complex network system govern a vast range of biological functions within our bodies, including speech, language, memory, learning, movement, and cognition. Thus, when our nervous system is compromised, neurological disorders such as Alzheimer’s, disease, multiple sclerosis, and Parkinson’s disease can manifest due to the damage and degeneration of neurons and their surrounding environment.

Neuroprotection refers to the interventions used by internal or external factors to protect the structural integrity of nerve cells, preserve their functionality and prevent the impairment of the nervous system. Neuroprotective interventions include pharmacological treatments and lifestyle changes that help to remedy neuronal damage or delay and inhibit the progression of nerve degeneration that often develops as a result of infections, trauma, consumption of toxic substances, genetic factors, inflammatory conditions, and ischaemia (a shortage of oxygen reaching nerve cells). 

Therefore, our diet and lifestyle play a significant role in enhancing or deteriorating the state of our health, as the right nutrients have the capacity for neuroprotection and mitigating neuronal impairment, whereas unbalanced diets can also subject our bodies to further inflammatory stress, worsening brain and neuronal health, therefore making us more susceptible to neurological damage. Fruits, in general, provide us with a range of useful vitamins and are rich in nutritional value. In this article, I will specifically outline how the nutrients in grapes have neuroprotective properties and how including them in your diet can help optimise the health of your nervous system.

Nutritional composition of grapes

Grapes are rich in various nutrients and are a beneficial source of dietary fibre and vitamins. They also have a high water content, which facilitates the hydration of the cells in our body. Grapes also contain the natural sugars called fructose and glucose, which provide the body with essential energy. The nutritional composition of grapes encompasses a range of bioactive compounds (compounds affecting an organism), making them a valuable addition to our diets. In particular, the antioxidant-rich nature of grapes is likely the main reason for their neuroprotective properties and vast health benefits.¹

Oxidative stress refers to a phenomenon which describes an excessive and unbalanced accumulation of reactive oxygen species (ROS). ROS are charged particles that are often produced by cells in our body during cell signalling processes or as a by-product of oxygen metabolism. However, they can also arise as a consequence of being exposed to environmental pollutants. When they are built up in excess, the body’s natural healing system and biological balance become disrupted, overburdened, and incapable of detoxifying and neutralising them. Consequently, they cause damage to cells and therefore tissues, by infiltrating the genetic material within cells, destroying their coding, and thus compromising the molecular integrity of cellular DNA due to their charged nature. 

Since our DNA contains the blueprints for the proteins that make up our cells and body, when it becomes compromised, the resulting proteins will most likely be dysfunctional, either damaging our body or failing to protect us from other types of damage. Hence, oxidative stress is a major cause of the majority of the diseases that are prevalent within our society.² Antioxidants like the ones present in grapes aid in the neutralisation process of ROS, and therefore we should incorporate antioxidant-rich food within our diets.³

Grapes are enriched with a range of powerful antioxidants, most notably quercetin, anthocyanins, and resveratrol. The latter recently became renowned by highly esteemed scientists, such as ageing and epigenetics researcher and Harvard graduate Dr David Sinclair, for its anti-ageing benefits.⁴ Studies have shown that each of these antioxidant polyphenols (a family of compounds found especially in fruits) has numerous health benefits, as listed below: 

Resveratrol 

It is a powerful anti-inflammatory compound which helps mitigate chronic inflammation, the primary cause of many diseases, especially those which affect our nervous system. The combination of its anti-inflammatory and antioxidant properties means that it is excellent at promoting heart health, anti-ageing, and is effective for neuroprotection, as it prevents age-related diseases and cognitive decline, therefore reducing the risk for neurodegenerative diseases like multiple sclerosis and Alzheimer’s disease.⁵ 

Quercetin 

Quercetin is a natural flavonoid (a class of polyphenols) found in various foods and exhibits notable neuroprotective properties that can benefit brain health. It serves as a potent antioxidant and anti-inflammatory agent, helping protect neurons from oxidative damage and reducing inflammation in the brain. These qualities are associated with improved cognitive function and a potential reduction in the risk of neurodegenerative diseases, including Alzheimer's and Parkinson's. Quercetin's ability to support healthy blood vessels and enhance circulation also contributes to its neuroprotective effects, by ensuring an adequate supply of oxygen and nutrients to brain cells. While more research is needed to fully understand quercetin’s mechanisms, it still holds promise as a compound that can promote and maintain cognitive well-being, making it a valuable component of a neuroprotective diet.

Anthocyanins 

Anthocyanins are natural pigments found in colourful fruits and vegetables, and they offer remarkable neuroprotective properties. These compounds are potent antioxidants, safeguarding brain cells from oxidative stress and inflammation, which, as aforementioned, are implicated in neurodegenerative conditions. Anthocyanins are associated with enhanced cognitive function and memory, reducing the risk of age-related cognitive decline and neurodegenerative diseases like Alzheimer's. Their ability to promote healthy blood vessels and blood flow to the brain further reinforces their neuroprotective effects. While ongoing research continues to explore their precise mechanisms, anthocyanins are also promising compounds that hold neuroprotective properties.⁶ 

Vitamins and minerals

Likewise, grapes are enriched with a range of vitamins and minerals that aid neuroprotection. Vitamin C, for example, provides strong antioxidant capabilities, protecting neurons from oxidative damage and supporting brain health. Vitamin K, another nutrient present in grapes, plays a role in cognitive function and may aid in reducing the risk of neurodegenerative diseases. Additionally, B vitamins found in grapes, such as vitamin B6 and folate, are crucial for neurotransmitter synthesis and cognitive performance. On the mineral front, grapes offer potassium, which helps maintain proper nerve cell function, and manganese, an essential element for brain health and enzyme activity. Together, the presence of these vitamins and minerals in grapes provides a holistic approach to neuroprotection by combating oxidative stress, supporting cognitive function, and maintaining the health of neural tissues.

Grapes and brain health 

The role of antioxidants in protecting brain health 

Recent studies have shown that grapes significantly impact the optimisation of brain health and alleviate neurological diseases. Some of the cognition-related improvements observed in response to increased grape consumption include enhanced focus and reaction time speeds in attention and memory tasks.⁷ Similarly, studies focusing on the effects of resveratrol within grapes on Alzheimer’s symptomatic presentation found that regional brain declines typically observed in early-stage Alzheimer’s were not observed in subjects that were administered grape formulations. These studies have consequently suggested that grapes may have neuroprotective properties, as they diminish the presentation of cognitive decline typically observed in early Alzheimer’s disease progression.^5,8

Grapes and neurodegenerative diseases

Oxidative stress is a major cause of neurodegenerative diseases, since the elevation in ROS deforms neural membranes and destroys otherwise functional cells, hence, the antioxidant properties of grapes serve as a great means of neuroprotection. For instance, Alzheimer’s disease manifests as a consequence of an accumulation of protein aggregates, named neurofibrillary tangles and Aβ plaques. This typically takes place within the brain regions called the hippocampus and cortex, which are responsible for memory and metacognition. These protein aggregates, which are a hallmark of Alzheimer’s disease, are strongly correlated with elevated ROS levels in the body. Therefore, an antioxidant-rich diet may help to slow disease progression and alleviate its symptoms.⁹

Similarly, the neurodegenerative disease Parkinson’s, which is characterised by a loss in mobility and impairment in motor function, can be tackled by the antioxidant and anti-inflammatory properties of grapes. The underlying pathology of Parkinson’s disease involves the loss and degeneration of dopaminergic neurons, which results in oxidative stress, inflammation, and mitochondrial dysfunction. All of these symptoms can be minimised through the neuroprotective nutrients in grapes.¹⁰ 

Glial cells are cells located in and around the nervous system that help support and protect neuronal health through a diverse range of functions, which include neurotransmitter regulation, structural support, immune support, and energy and waste exchange. This includes repairing nerve cells and removing dead or damaged neurons. Recent studies of polyphenols (compounds like resveratrol, quercetin, and anthocyanins) found in grapes have demonstrated in rats that 13 of the proteins found in astrocytes, including the glial fibrillary acidic protein (GFAP) were altered, following the administration of grape polyphenols. GFAP repairs neurons, is activated in response to brain trauma or injury, and is considered a diagnostic biomarker of numerous neurological diseases. Glial cells have a vital role in the process of neurodegeneration, and studies have also revealed that grape seed extracts protect against neuronal death and oxidative stress via mechanisms mediated by alterations of the gene interleukin-6, responsible for the production of the defence protein IL-6.¹¹ 

Similarly, a growing body of research confirms that oral administration of grape extract polyphenols effectively provides neuronal protection against neurodegeneration that arises after strokes and episodes of cerebral ischaemia (blood flow restriction to the brain).^12,13,14 This is perhaps owed to the polyphenols’ antioxidant and anti-inflammatory properties enhancing blood flow through a range of mechanisms. The polyphenols in grapes promote vasodilation, a process described as the widening of blood vessels, which improves circulation and reduces vascular pressure. Likewise, antioxidation aids by protecting blood vessels against rupturing, an event that is often caused by oxidative stress. Increased blood flow is crucial in assisting healing and prevention of neuronal damage since it provides nerve cells with sufficient amounts of oxygenated blood, which is required for energy metabolism and sustaining the nerve cells’ structural and functional integrity. In turn, protects the nervous system against neurodegeneration.

Varieties of grapes and their neuroprotective function

Green and red grapes, grape seed extracts and different grape species contain different concentrations of nutrients and beneficial bioactive compounds and may, therefore, vary in their neuroprotective impact.¹⁵ For instance, studies of concord grapes have demonstrated an anti-ageing impact. As we age, we all begin to experience deficits in our cognitive and motor function due to our bodies being overburdened with inflammation and oxidative stress. An increased consumption of polyphenolic compounds, such as those found in grapes, has been found to reduce, and even reverse, these age-related declines.¹⁶ Additionally, red grapes have a much higher concentration of resveratrol and anthocyanins compared to green grapes, whereas both of them have high antioxidant content and regulate blood flow and circulation.

Summary

To summarise, grapes are enriched with a variety of vitamins and nutrients that have special antioxidant and anti-inflammatory properties that help optimise neuronal health and reverse or limit neuronal damage. Studies have demonstrated the proven efficacy of nutrients derived from grapes. While the evidence supporting the neuroprotective efficacy of grape extracts is substantial, current research still seems to be inconclusive regarding its understanding of the possible grape formulation and dosages that are required to achieve therapeutic effects, should the nutrients within grapes be considered to be a viable pharmacological treatment. 

Similarly, further research is required to establish whether the pharmacological effects of grape extracts arise due to the interaction of all the nutrients within grapes or if specific biological compounds, like resveratrol, are producing these neuroprotective effects independently of one another. Moreover, further research is necessary to explore whether these effects are still impactful following neuronal injury or if the protective qualities of grapes are exclusively activated as a means for preventing neurodegeneration.