Genetics of eating

Our genes determine our nutritional deficiencies

As our diets change, our genes evolve. You become what you eat. People in Asia were hunter-gatherers and have a higher risk of lactose intolerance compared to those in the Middle East, where dairy farming began.

While developing skin serums and anti-ageing products, I realised that the same anti-oxidant cellular pathways that mediate injury, inflammation, cancer and stress also regulate ageing. In other words, if you are in an abusive relationship or under stress, you will look older. If you have cancer or a chronic illness you will look older. One cannot have bad health and good skin! We know that signs of ageing like baldness and wrinkling skin denote a higher risk of heart disease. We all know vitamin C is good for skin — but consuming too many vitamin supplements is essentially a waste of time and money! Let’s look at some examples where genetics can help personalise health.

Vitamin deficiencies

The vitamin C story has a special connection with India. In 1497, Vasco Da Gama began his voyage around the Cape of Good Hope in search of the famed East Indies or India. Out of 160 men that sailed with him 60 died. No one knew what caused the mysterious illness that afflicted them, although it was later referred to as scurvy because of the terrible mouth ulcers it caused.

James Lind, a Scottish surgeon ran the world’s first proper clinical trial aboard the HMS Salisbury in 1747. From a modern-day clinical perspective, Lind’s experiment was a “six-armed clinical trial” comparing the then six known treatments for scurvy — oranges and lemons, an elixir of vitriol, vinegar, cider, sea water, and nutmeg. Only the seamen taking lemons and oranges recovered. This was 200 years before independence but India is still not independent of vitamin C deficiency!

A recent study of over 2,500 people in both north and south India found the prevalence of vitamin C deficiency to be greater than 50%. We know vitamin C is found in fresh oranges, lemons and many vegetables. However, while poor diets due to malnutrition and smoking no doubt contribute, the process of cooking leafy vegetables destroys vitamin C and because of the lack of drinking water, in India we eat less of salads and advocate cooked foods which lose their vitamin C.

Vitamin C is a potent antioxidant it is as if people who lack vitamin C have an engine with a spark plug missing. Research has turned up another interesting aspect — one in five individuals — therefore many reading this will have a non-functioning variant of GSTT-1, a faulty vitamin C gene. So even if you were wealthy and eating a good diet with the recommended daily amount of vitamin C, it may not be enough for you.

Studies were done in young people in their 20s in both North America and Asia — those with these genes gained a tiny amount of weight each year, their blood pressure went up by a minuscule amount, as did their sugar. This is so gradual that no one notices it until your middle-aged photo does not look anything like your university college photo — and you end up in your 40s or 50s — overweight, with a borderline sugar or blood pressure — and eating an orange a day could literally have kept the doctor away!

Allergies & more

If you are a fast metaboliser of coffee, coffee is good for you; but it may be bad for others. Some people have a degree of lactose intolerance, hence it is best that they avoid milk. Geography and gastronomy can influence genes — genetic predisposition to gluten allergy is more common in wheat-eating north India whereas coeliac disease, the severe form of gluten allergy is virtually unknown in rice-eating south India. Coeliac disease affects our immune system and causes problems in liver, thyroid and other organs. But optimising health includes not just eating but exercising for gene type.

This year, the soccer World Cup will be played in Russia. India with a fifth of the world’s population will not be represented and has never been in the playoffs. Studies done comparing vitamin D levels in soccer players shows that the level of vitamin D is directly related to muscle strength, aerobic capacity, and speed in professional soccer players. This is also useful in track and field, and other sports where India struggles to do well.

Indian sub-continental skin has the least amount of vitamin D because being brown-skinned we do not absorb enough vitamin D properly. We avoid the sun and most people don’t eat fish. It isn’t an accident the three states known to be better at soccer traditionally — Goa, Bengal and Kerala have the highest fish consumption. It doesn’t mean we all should eat fish like salmon, cod, tuna or sardines that have vitamin D to play soccer but understanding your vitamin D genes means you can supplement the nutrient in optimal amounts adjusted for individual athletes.

Vitamin D is a calcium regulator. When a large population of vegetarians, generally low in vitamin D consumes large amounts of milk or dairy that contains calcium, the calcium becomes intracellular leading to higher rates of heart disease and type 2 diabetes. The cases of heart disease and diabetes in India are rising. And that’s where knowing your gene type helps. Heart disease is called India’s time-bomb, but the best health strategy is not defusing these bombs, but stopping making
them!

The future is all about personalising health for specific populations. We can even predict people who will get side effects from certain medications and this is the future of prescribing.

Genes may be our blueprints, but we don’t have to let them be our destiny!

(The author has penned the book ‘The Genetics of Health’)