Bad. And for four reasons.
- Ordinary Coke and Pepsi are full of sugar. A 335ml can of Coke has 38g of sugar which is 9 teaspoons! Even the new Coke Life has 22g (5.5 teaspoons) of sugar. When you drink them that sugar is quickly digested into glucose which is rapidly absorbed into the blood stream. The body does not like this and gets the pancreas to pump out insulin to cause the muscle and fat cells to suck that glucose out of the blood. The resulting insulin spikes will raise DHT levels. More DHT means less hair.
- Diet Coke and Diet Pepsi use aspartame as its sweetener. There is evidence to suggest that aspartame alters our gut microbiome (AKA microflora). These are the normal “good” bacteria that live in our intestines. When exposed to artificial sweeteners like aspartame, saccharin and sucralose (but not xylitol) the type of bacteria in the microbiome changes. That change is not good, there is a rise in the number of bacteria which increase the size of the insulin spike caused by glucose. No one is sure how this happens but it does. Greater insulin spikes means more DHT.
- The lining of the aluminium cans. Glass and PET plastic do not have health effects but the lining of the aluminium cans leach the chemical BPA into your drink. BPA is an endocrine disrupting chemical, one of a group of chemicals which have hormonal effects in the body, in this case affecting the thyroid hormone. Evidence is not conclusive but suggests BPA switches off hair follicles.
- The dark caramel colour which contains many advanced glycation endproducts (AGEs). AGEs cause permanent inflammatory damage to hair follicles. AGEs are formed by heating glucose with a protein creating a permanent brown compound. When this protein is the gluten in bread we get a brown crust on our bread or toast. When it happens in the lens of our eye we get a cataract. When it happens to one of the body’s enzymes that enzyme changes shape and stops working. Dietary AGEs like toast or caramel food colour come ready made in our food. They are absorbed into the bloodstream and travel around causing inflammation, especially to the hair follicles. This damages those follicles, accelerates grey hair and means fewer thinner hairs.
Water is still the best cold drink. Coke and Pepsi are probably the worst for your hair.