Yes. If it dissolves in water it is soluble. Sugar, salt, soap are all soluble. Try it.
Example: some hydroxides are suluble in water but other aren't soluble.
sport drinks have a lower water content but higher water suluble content than your body
Phloroglucinol is not so suluble in water (1o g/L); dissolve 10 g phloroglucinol in 100 mL demineralized water.
Vegetarians get al their requirements of nutrients from starch in grains, priteins frim pulses ,most of the other nutrients from vegetable greens and oil suluble vitamins from diary products.
Sugar is not suluble in water inspite of the fact that it is not visible after we drop it into water. They are still two substances. However, salt is soluble in water which means that it lost its chemical integrity after we drop it into water.
The difference between fat soluble and water soluble vitamins is that fat soluble vitamins are not easily excreted in the body. They can retain for a period of time.Water soluble vitamins are excreted easily out of the body through urination, perspiration or defecation and vomitting.