We suggest a new mechanism for naturally suppressing dimension five baryon number violating in supersymmetric SU(5+ N) ( N=0,1,…) GUTs. The mechanism is realized through suppression of qqT type couplings, and is implemented by introducing new `matter' multiplets belonging to symmetric representations of SU(5+ N). Together with the suppression of nucleon decay, these multiplets also enable one to avoid the unwanted asymptotic mass relations m s = m μ , m d / m s = m e / m μ . As an example, we consider an SU(6) model with pseudo-Goldstone Higgs. By supplementing the model with an anomalous U(1) flavor symmetry, we also obtain a simple `all-order' solution of the gauge hierarchy problem and natural explanation of charged fermion mass hierarchies and values of the CKM matrix elements. The proton life time τ p ∼10 2 τ p SU(5) yr. is compatible with experiments, with the dominant decay being p→ Kν μ, τ . Thanks to the SU(6) symmetry, successful unification of the gauge couplings can be retained, and the value of the strong coupling α s ( M Z ) can be reduced to ≃0.12. Finally, we show how to accommodate the solar and atmospheric neutrino data through the bi-maximal neutrino mixing scenario, with maximal vacuum ν e − ν μ, τ and large angle ν μ − ν τ oscillations.