Ayurveda demonstrates that if used appropriately, poison can work as ambrosia and, if used inappropriately, ambrosia can be as fatal as poison.

Ayurveda considers ghee, honey and gingelly oil (oil extracted from sesame seeds) master medicines that are extremely beneficial to the human body. A va?ta prakr?ti person, a pitta prakr?ti person and a kapha prakr?ti person can use gingelly oil, ghee and honey, respectively, as preferred carriers of medicine. Having said that, these very substances can cause imbalances in certain conditions:

• Overconsumption of ghee, having ghee at night and drinking cold water after consuming ghee are not healthy habits and can create blockages in arteries.
• Honey and ghee consumed in equal quantities can be poisonous. If these two have to be consumed together at all, one should be double the quantity of the other—else, we experience ma?tra? viruddha (dose incompatibility).
• Heating honey, pouring honey into hot drinks or consumption of honey by a person coming in from hot weather are all unhealthy practices. This is called sam?ska?ra viruddha (processing incompatibility).
• Drinking hot water after consuming honey is called krama viruddha (order incompatibility). Overconsumption of honey leads to constipation.

Now let’s look at potential harmful impacts of other foods that are, on most occasions, healthy:

• Uncooked food and salads can be unhealthy in the monsoon. The same goes for pungent substances in the summer and cold substances in the winter. This is called ka?la viruddha (time incompatibility).
• Daily consumption of large quantities of curd or consumption of curd at night is unhealthy. Boiled curds are especially toxic. Curds should be consumed with black pepper, moong dal (split green gram) soup or gooseberry pickle.
• Certain food combinations are unhealthy. Milk consumed with horse gram or fish causes veerya viruddha (potency incompatibility). Citrus fruit salad with milk is samyoga viruddha (combination incompatibility). The same goes for jackfruit and fish.
• Certain varieties of barley—an otherwise healthy food— can be toxic.
• Even water can be unhealthy—water from alkaline regions, for example. Meanwhile, it is already established that overconsumption of water puts extra stress on the kidneys, washes away important nutrients from the body and strains the system. Similarly, drinking non-boiled water can hinder the process of weight loss. Boiled water is light and easy to digest. It increases appetite and percolates well into the tissues. Cold water does not. Besides, drinking cold water immediately after having a hot beverage causes parihar viruddha (contraindication incompatibility). Hence, it is advised to boil drinking water.

Meanwhile, cobra venom, an otherwise lethal substance, can save lives. Ayurveda uses medicines made using cobra venom for liver cirrhosis, cataract and chronic blocks.

So the key question is not whether something is healthy or unhealthy. Instead, we can ask ourselves: Do we know enough about the intrinsic nature of the substance to understand when it will be healthy and when it will be harmful?

The above has been excerpted with permission from the book, Ayurveda—The true way to restore your health and happiness written by Dr G.G. Gangadharan, and published by Ebury Press an imprint of Penguin Random House.