Highly seasoned dishes, hot curries, chutnies, meat, fishes, chillies, sour articles, tamarind, mustard, all kinds of oil, asafoetida, salt, garlic, onions, urad-ki-dal (black gram), all bitter things, dry foods, black sugar, vinegar, alcohol, sour curd, stale foods, acids, astringents, pungent stuff, roasted things, heavy vegetables, over-ripe or unripe fruits, pumpkins, etc., must be avoided. Meat can make man a scientist, but rarely a Philosopher, Yogi or a Tattva Jnani. Onions and garlic are worse than meat. All food-stuffs contain a small quantity of salt. So, even if you do not add salt separately, the system will derive the necessary quantity of salt from other food-stuffs. The giving up of salt will not produce deficiency of hydrochloric acid and dyspepsia as allopathic doctors foolishly imagine. Salt excites passion. No ill-effects are produced by the giving up of salt. Mahatma Gandhi and Swami Yogananda had given up salt for over thirteen years. Giving up salt helps you in controlling the tongue and thereby the mind also and in developing will-power too. You will have good health. Sitting before fire, company of women and worldly-minded people, Yatra [pilgrimage], long walk, carrying heavy burdens, cold bath in the early morning, harsh words, speaking untruth, dishonest practices, theft, killing animals, Himsa [harming] of all kinds either in thought, word or deed, hatred and enmity towards any person, fighting, quarreling, pride, double-dealing, intriguing, back-biting, tale-bearing, crookedness, talks other than those of Atman and Moksha, cruelty towards animals and men, too much fasting or eating only once every day, etc., are not allowed for a Pranayama-practitioner.
-From Sri Swami Sivananda's "The Science of Pranayama"
Which reminds me: I'll lead a Pranayama Workshop on Saturday, 4/28 at Sweet Pea's Studio. It is highly recommended for those who have a regular asana practice and want to go deeper. Register and learn more here.