Mutations in two regulatory genes of white grapes turn off production of anthocyanins which are responsible for the color of purple grapes. Anthocyanins and other pigment chemicals of the larger family of polyphenols in purple grapes are responsible for the varying shades of purple in red wines.
- Has many health benefits – Apart from potential benefits of alcohol itself( in cases where grapes are processed into red wine) like reduced platelet aggregation and vasodilation, the grape skin provide other suspected health benefits, such as: alteration of molecular mechanisms in blood vessels, reducing susceptibility to vascular damage, decreased activity of angiotensin - a systemic hormone causing blood vessel constriction that would elevate blood pressure and increased production of the vasodilator hormone called nitric oxide (endothelium-derived relaxing factor).
- Reservatol benefits – Grape phytochemicals such as resveratrol (a polyphenol antioxidant), have been positively linked to inhibiting some cancers, heart diseases, degenerative nerve diseases, viral infections and mechanisms of Alzheimer's disease. Protection of the genome through antioxidant actions may be a general function of resveratrol. Resveratrol bears a significant transcriptional overlap with the beneficial effects of calorie restriction in heart, skeletal muscle and brain. Both dietary interventions inhibit gene expression associated with heart and skeletal muscle aging, and prevent age-related heart failure.
- Red wine (phenols) benefits – Red wine may offer health benefits more so than white wines because the potentially beneficial compounds are present in grape skin - only red wine is fermented with skins. The amount of fermentation time a wine spends in contact with grape skins is an important determinant of its resveratrol content. Wines produced from muscadine grapes may contain more than 40 mg/L. In muscadine skins, ellagic acid, myricetin, quercetin, kaempferol, and trans-resveratrol are major phenolics.
- Grape seed benefits (constituent) – biochemical and medical studies have demonstrated significant antioxidant properties of grape seed proanthocyanidins. Together with tannins, polyphenols and polyunsaturated fatty acids, these seed constituents display inhibitory activities against several experimental disease, including cancer, failure and other disorders of oxidative stress. Grape seed oil from crushed seeds is used in cosmetics and skincare products for many perceived health benefits. Grape seed oil has some amount of tocopherols (vitamin E), but is notable for its high contents of phytosterols, polyunsaturated fatty acids such as linoleic acid, oleic acid and alpha-linolenic acid.
- Concord grape juice benefits – although the benefits of grapes are most likely similar (like phenol and reservatol benefits), there are specific grape varieties (like the Concord Grape) which have been applied in medical research studies, showing potential benefits against the onset stage of cancer, platelet aggregation and other risk factors of atherosclerosis as well as loss of physical performance and mental acuity during aging and hypertension in humans.
- Grape toxicity in dogs - Grapes can cause renal failure in dogs. Reasons for this is not yet very clear, but the probable culprit is polyphenols like resveratrol and syringetin 3-O-galactoside.