Coffee does lots of things to your body. Including:
Caffeine makes your heart beat faster and raises blood pressure. It widens blood vessels and excites the system that conducts electrical impulses, which can lead to palpitations. It lowers blood sugar levels and increases circulating cholesterol and free fatty acids (triglycerides) risking heart attacks. concentration and relieve tiredness. It can speed up thought processes, improve memory and produce feelings of wellbeing.
Caffeine withdrawal however can cause persistent headaches. It also seems to worsen the mood swings, irritability and anxiety symptoms of PMT and the menopause.
Caffeine arouses the sympathetic nervous system’s ‘fight or flight’ responses, increasing pulse, breathing rate and muscle tension. It raises the level of norepinephrine, a brain chemical that increases alertness and can cause insomnia.
It speeds up metabolism and stimulates certain enzyme activities in the liver. This can alter the effects that some medicines have. i.e. caffeine boosts the pain-killing effect of asprin. It takes 4 hours for half the caffeine in a cup of coffee to be metabolised, but much longer in people with liver disease and up to 7 times longer in late pregnancy.
Caffeine stimulates gut muscle to contract and therefore has a laxative effect. This can also contribute to the loss of essential nutrients such as B vitamins and minerals from the body.
Large amounts of caffeine can cause pain and nausea and people prone to heartburn should avoid it.
Caffeine acts as a diuretic reducing body water and leading to dehydration. It dilates the blood vessels in the kidneys and speeds up the elimination of minerals and vitamins that are essential to health. B6 is vital for preventing kidney stones, as is magnesium, and people with kidney stones should avoid caffeine.
Caffeine stimulates the adrenal glands to produce extra hormones to help increase blood sugar. By overstimulating these glands, caffeine weakens them, which, in time will lead to persistent fatigue.
Caffeine slightly increases the excretion of calcium through the kidneys creating a risk factor for osteoporosis.
Caffeine can dehydrate the skin making it dry and itchy. People prone to eczema should avoid it.