A tree is a plant with an elongated stem, or trunk, supporting branches and leaves in most species. Trees tend to be long-lived, some reaching several thousand years old. Trees have been in existence for 370 million years.
A variety of plant species have independently evolved a woody trunk and branches to compete for sunlight. In more general sense, tall palms, tree ferns, bananas and bamboos are also trees. The roots branch out under the ground to anchor the tree and to extract moisture and nutrients from the soil. Above ground, the branches usually bear leaves, which capture light.
Trees reduce erosion and moderate the climate. Trees and forests provide a habitat for many species of animals and plants. Some trees provide edible fruit.
Vitamin B3, Niacin, nicotinic acid, helps to convert food into energy and is essential for healthy skin, blood cells, brain, and nervous system. It is one of 8 B vitamins. It is water-soluble, which means it is not stored in the body. It has 2 other forms, niacinamide (nicotinamide) and inositol hexanicotinate, which have different effects.
Niacin occurs naturally in food and can also be made by your body from the amino acid tryptophan, with the help of B6.
It is rare for anyone in the developed world to have a Vitamin B3 deficiency; alcoholism is the main cause of it in the US.
Recommended daily amount: 14 - 16 mg.
Example sources: whole grains, mushrooms, peanuts and other legumes.