It depends on the case; there is no single guideline.
Effect by goal · level of evidence
Cholesterol and cardiovascular risk
reducesLowstudy (AA)
33%
Small crossover study (10 people, 2 weeks): a diet based on leafy greens, fruit, and nuts greatly lowered LDL cholesterol (~33%) versus the usual diet. Very few people and short term, but a large effect.
Cholesterol and cardiovascular risk — reduces (Low, study). Small crossover study (10 people, 2 weeks): a diet based on leafy greens, fruit, and nuts greatly lowered LDL cholesterol (~33%) compared with the usual diet. Very few people and short term, but a large effect. 9160820
Information, not medical advice. Prescription drugs require a doctor.
Information, not medical advice. Scientific evidence reflects the quality of the studies.