India has a long history of using natural medicines to treat ailments.
There is a belief that illness can be linked to habitual patterns, which in turn are closely connected to thought processes, emotional health and food preferences. Changing these patterns, practitioners claim, means using ingredients that address all three aspects.
Kavita Devgan, nutritionist and author of Ultimate Grandmother Hacks: 50 Kickass Traditional Habits for a Fitter You, believes that Indian spices and plant-based ingredients are packed with healing properties.
"Green leafy vegetables and sprouts have vitamins B and E, which help in digestion and also aid in excreting acid from the body. Barley grass, for instance, helps correct alkalinity and boosts the metabolism and immune system."
Here are five plant-based "healing foods": turmeric, moringa, ashwagandha, garlic and ginger.
Turmeric takes centre stage in the masala dabba, or spice box. It is regarded as sacred, and is offered to deities and applied to newlyweds' skin. It is customarily stirred into warm milk and drunk at bedtime to nurse colds and coughs. Fresh turmeric root can be preserved in a salt and chilli powder base.
Devgan says: "Turmeric is apparently the original probiotic" which "when taken with high-protein foods, assists in digestion and prevents formation of gas".
In her book, Turmeric - The Wonder Spice, food historian and writer Colleen Taylor Sen discusses the merits of this spice and the role it has played in Indian, Chinese, and Indonesian medicine. It has over the centuries been used to treat gastrointestinal and pulmonary disorders, diabetes, atherosclerosis and bacterial infections.
A plethora of studies have been done to test turmeric's benefits. A 2016 meta study of clinical trials of turmeric found evidence to support its efficacy in treating arthritis, though it concluded that the small size and poor quality of most of the studies "were not sufficient to draw definitive conclusions" about the spice.
Indians have for years used moringa in their cooking: the leaves are cooked in a soupy gravy with lentils and eaten with rice, fried until crisp and used to make dry chutneys, and mixed with spices and coconut for wet chutneys.
The moringa tree is also known as the drumstick tree, the Miracle Tree, the Tree of Life and Mother's Milk. Why? According to NGO the International Tree Foundation, it is one of the most nutrient-dense plants.
Solomon Ternder, a moringa advocate and author of books on the plant, points to research carried out by the non-profit World Vegetable Centre in Taiwan that found moringa had the highest nutritional value among 120 foods studied. Ternder says that 100 grams of fresh moringa leaves "provides more protein than an egg, more iron than a steak, more vitamin C than an orange and more calcium than a glass of milk".
In addition, Ternder claims that moringa has antibiotic, antimicrobial and antibacterial properties, and that its high vitamin B content aids in digestion.
Indian ginseng, or ashwagandha (in Sanskrit ashwa means horse and gandha means fragrance) has very strong smelling roots. Proponents claim that it restores vigour and strength, revitalises tissue and muscles, fights asthma and reduces cholesterol.
Sri Maa Sidh Sidhshakti Ji, "inner scientist" and founder of the Institute of Spiritual Sciences (IOSS) in India, says that ashwagandha is beneficial for the body and the brain.
"It has a rejuvenating and calming influence on the nervous system," she claims. "It is used exclusively in Ayurveda (traditional Indian medicine), and is an ingredient in chyawanprash (a nutrient-rich, rejuvenative jam)."
However, Sri Maa warns that due to its potency, you should consult a doctor before using it. It can have severe side effects, from diarrhoea and gastrointestinal disorders to thyroid dysfunction. She adds that pregnant or nursing mothers, young children and people with severe kidney or liver disease should avoid the plant.
Several studies have been conducted on the effectiveness of ashwagandha, including one reported in the Indian Journal of Psychological Medicine in 2012 that suggest it might have a role in lowering stress.
This pungent bulb, rich in vitamins and dietary minerals, has been used as a remedy to alleviate colds and fevers, balance high blood pressure and high cholesterol, improve digestion and enhance bone strength.
Devgan endorses the use of garlic, and recommends "one or two crushed garlic cloves with water on an empty stomach every day". Garlic, she claims in her book, helps to prevent cancers, lowers cholesterol and protects the heart.
A 2014 review of the available scientific research into garlic's potential therapeutic effects, published in the Avicenna Journal of Phytomedicine, said: "Different compounds in garlic are thought to reduce the risk for cardiovascular diseases, have anti-tumour and antimicrobial effects, and show benefit on high blood glucose concentration."
A Chinese study published in the Asia Pacific Journal of Clinical Oncology this year suggests eating allium vegetables such as garlic, leeks and onions might reduce the risk of colorectal cancer.
One of the most common "grandma remedies" in the Indian household is ginger juice mixed with honey, which can alleviate sore throat and coughs. It is packed with bioactive compounds, and some say it can help prevent indigestion and nausea.
According to Sri Maa, it is also effective for osteoarthritis. "Mix ginger, mastic, cinnamon and apply to painful areas." For pain relief, Sri Maa also recommends applying a hot ginger poultice to affected areas, though not on broken skin.
In Herbal Medicine: Biomolecular and Clinical Aspects, researchers Ann Bode and Dong Zigang report on "the amazing and mighty ginger" - the title of the chapter which reviews the many studies into the evidence for its effectiveness as an antioxidant, anti-inflammatory agent, anti-nausea compound, and anti-cancer agent, and its protective effect against other disease conditions.
They suggest that ginger's "specific biological targets are largely unknown and remain to be determined", and conclude that, "in spite of the lack of specific mechanistic information, use of ginger appears to be safe and its effects are mighty and amazing in its many applications".
Devgan's overall advice for good health mirrors closely the conventional messaging on foods from global authorities: avoid fatty, processed and refined foods, and cut down on caffeine. She is also a proponent of yoga and meditation for their numerous health benefits.
This article was first published in South China Morning Post.