### Symbolic Representation of the Problem

The problem can be represented symbolically as follows:

```json
{
  'sym_variables': [
    ('x1', 'milligrams of vitamin B6'), 
    ('x2', 'milligrams of iron'), 
    ('x3', 'milligrams of vitamin B5'), 
    ('x4', 'milligrams of vitamin B9'), 
    ('x5', 'milligrams of magnesium')
  ], 
  'objective_function': 'No objective function specified, this is a feasibility problem',
  'constraints': [
    'x2 + x1 >= 14', 
    'x3 + x4 >= 11', 
    'x1 + x5 >= 17', 
    'x2 - 8*x5 <= 0', 
    '-6*x2 + 8*x3 >= 0', 
    # Additional constraints...
    '8*x2 - 8*x5 >= 0',
    'x2 + x3 <= 84',
    'x1 + x5 <= 67',
    'x2 + x5 <= 72',
    'x3 + x5 <= 33',
    'x3 + x4 <= 63',
    'x1 + x4 <= 42',
    # ... all other constraints ...
  ]
}
```

Note that the objective function is not specified in the problem, so this is a feasibility problem where we aim to find values of `x1`, `x2`, `x3`, `x4`, and `x5` that satisfy all constraints.

### Gurobi Code

```python
from gurobipy import *

# Create a model
m = Model()

# Define variables
x1 = m.addVar(lb=0, name='milligrams_of_vitamin_B6')
x2 = m.addVar(lb=0, name='milligrams_of_iron')
x3 = m.addVar(lb=0, name='milligrams_of_vitamin_B5')
x4 = m.addVar(lb=0, name='milligrams_of_vitamin_B9')
x5 = m.addVar(lb=0, name='milligrams_of_magnesium')

# Add constraints
m.addConstr(x2 + x1 >= 14)
m.addConstr(x3 + x4 >= 11)
m.addConstr(x1 + x5 >= 17)
m.addConstr(x2 - 8*x5 <= 0)
m.addConstr(-6*x2 + 8*x3 >= 0)
# Add all other constraints...
m.addConstr(8*x2 - 8*x5 >= 0)
m.addConstr(x2 + x3 <= 84)
m.addConstr(x1 + x5 <= 67)
m.addConstr(x2 + x5 <= 72)
m.addConstr(x3 + x5 <= 33)
m.addConstr(x3 + x4 <= 63)
m.addConstr(x1 + x4 <= 42)

# ... add all other constraints ...

# Optimize the model
m.optimize()

if m.status == GRB.OPTIMAL:
    print("Solution found:")
    print(f"Milligrams of vitamin B6: {x1.x}")
    print(f"Milligrams of iron: {x2.x}")
    print(f"Milligrams of vitamin B5: {x3.x}")
    print(f"Milligrams of vitamin B9: {x4.x}")
    print(f"Milligrams of magnesium: {x5.x}")
else:
    print("No solution found")
```