Condensed Milk:

Condensed milk is cow's milk from which water has been removed. It is most often found in the form of sweetened condensed milk (SCM), with sugar added, and the two terms "condensed milk" and "sweetened condensed milk" are often used synonymously today. Sweetened condensed milk is a very thick, sweet product which when canned can last for years without refrigeration if unopened. Unsweetened condensed milk products spoil more easily and are now uncommon. Condensed milk is used in numerous dessert dishes in many countries.

Canned milk with sugar added and much of the water removed- Merriam-Webster

It's cow's milk from which the water has been removed and a sweetener added 

What ingredients need to make Condensed Milk?

1. whole milk2. unrefined sugar (organic cane sugar) 3. butter4. vanilla or vanilla extract5. breaking powder

Uses for condensed milk:

1. To make Brand2. Making Homemade Caramel3. Ice Cream4. Making Chocolate5. Tea6. Cake etc.

Bad effects of condensed milk

It's likely no surprise that sweetened condensed milk is dense in calories. After all, it is used as an ingredient in some very rich desserts. However, as far as sweets go, condensed milk has some redeeming qualities, namely, the nutrition that it derives from the milk solids it is made from. The key to enjoying condensed milk as a part of a healthy diet is consuming small, measured portions.

Calories

Sweetened condensed milk is a decadent treat, as it contains 62 calories for a mere tablespoon. Condensed milk is high in calories for the reason that its name implies -- it is a dense mixture of milk

solids and sugar. People who are dieting should either avoid condensed milk or consume it very judiciously.

Fat

A 1 tbsp. serving of regular sweetened condensed milk contains almost 2 g of fat, according to the USDA. The fat in condensed milk is primarily saturated fat, which can negatively impact cardiovascular health.

Protein and Carbohydrates

A tablespoon of sweetened condensed milk contains over 10 g of carbohydrates, all of which are sugars. A diet high in refined sugars can lead to weight problems, cardiovascular problems and diabetes, as some can contain amounts of sugar that you may deem unacceptable for a weight management or blood sugar control plan.

Effects in tea

In a small study conducted on 16 healthy women, scientists compared the effects of tea on their vascular system, with tea, water and tea with milk. They found that tea relaxes blood vessels (improves flow-mediated dilation), but tea with milk does not.

Researchers believe that the most likely explanation is that the caseins, proteins found in milk, form complexes with catechins in tea, its most important flavonoids.