Best Glue for Wood to Wood
Long grain wood joints:
Think gluing 2x4's side by side. When gluing with the long grain of the wood, it's best to use a PVA glue, and most woodworkers prefer a standard yellow PVA wood glue. Apply a thin coat of adhesive, clamp the joint, and clean up any squeeze-out.
End grain wood joints:
Think gluing 2x4's end to end. Polyurethane glues are good for this, since the polyurethane glue expands as it dries and can penetrate farther into the straw-like structures of the end grain. It's recommended to lightly dampen one side of the joint with a wet sponge or cloth, apply a thin coat of adhesive, clamp the joint, and clean up any squeeze-out.
These FDA approved food-safe adhesives are designed to come into contact with food.
For joints that will definitely be exposed to moisture, it's important to use the most water-resistant glues available. ANSI has 2 standards for water-resistant wood glues, and these ANSI Type 1 water-resistant glues are some of the most waterproof wood glues commonly available.
For joints that may occasionally be exposed to moisture, it's important to use a water-resistant glue. ANSI has 2 standards for water-resistant wood glues. These Type 2 glues are somewhat water-resistant and may be cheaper or have better working properties than Type 1 glues. Thus they may be more appropriate than Type 1 in some situations.