The phrase "are needed for normal" is correct and usable in written English.
It can be used in contexts where you are discussing requirements or necessities for something to function properly or to be considered normal.
Example: "Certain nutrients are needed for normal bodily functions and overall health."
Alternatives: "are essential for typical" or "are required for standard".
NF1 gene expression and function are needed for normal fracture healing [92].
These long-chain PUFAs are needed for normal brain development and function.
TRPV1 channels in the suburothelium are needed for normal excitability of low-threshold bladder fibres.
Appropriate function of the menisci are needed for normal knee biomechanical function.
Thus, both estrogen and androgens are needed for normal exocrine gland function.
Pancreatic beta cells express ATP-sensitive potassium (KATP) channels that are needed for normal insulin secretion and are targets for drugs that modulate insulin secretion.
Now scientists know why: Two copies of a critical gene appear to be needed for normal growth, and Turner's survivors have only one.
Air entraining admixture dosages of up to 10 times the recommended dosage were necessary to obtain minimal air void properties similar to what is needed for normal portland cement concretes subjected to freezing conditions.
Some physiological load is needed for normal bone growth, [[2]] but exceeding this physiological load can lead to unwanted morphological changes and different pathologies of the bone and joints [[3],[4]].
Reciprocal crosses of ASHH2/ashh2 heterozygous plants indicated that ASHH2 is needed for normal development or function of the haploid gametophytes (Figures 2A and 2B, Table 2).
SscB is needed for normal secretion and function of the SseF T3SS effector, which in turn is required for Salmonella-induced epithelial cell filamentation and bacterial proliferation in macrophages [42].
