A teaspoon of cod liver oil – plus other old wives tales that aren’t as healthy as you think

Generations of British children were subjected to it, each and every morning before breakfast. Cod liver oil, slipped off a cold metallic tablespoon and down the throat, while holding the nose. It made the small recipients shudder – sometimes even gag – but it would also make them grow up big and strong. So they endured it. But was it all for nothing? A new study, published in BMJ Medicine, has suddenly cast this traditional remedy into doubt. Which raises the question – if cod liver oil is not all it was cracked up to be, then what other old wives tales have we been swallowing?

A spoonful of cod liver oil for the heart: False

The study in BMJ Medicine focused on regular fish oil. But there is a distinction to be made between cod liver oil and regulator fish oil, says Dr Neil Srinivasan, a heart rhythm specialist and an expert in the management of irregular heartbeats (also known as atrial fibrillation) on which this new study focuses. 

“Cod liver oil, as its name suggests, comes from the livers of codfish,” explains Dr Srinivasan. Ordinary fish oil, on the other hand, is extracted from the tissue of oily fish like tuna, herring and mackerel. “They’re two different health supplements, from different fish sources and with unique benefits.” One thing they do have in common is that they are a good source of omega-3 fatty acids – healthy fats that can help to raise good cholesterol and lower triglycerides.

Cod liver oil specifically, has other potential health benefits. The liver is a potent source of fat-soluble vitamin A (important for healthy eyes, brain function, and skin) and also D (which helps the bones by regulating calcium absorption). So what to do? Overall, Dr Srinivasan recommends taking up a Mediterranean diet that involves eating more oily fish like anchovies and mackerel without swallowing supplements. 

So what about regular fish oil? Data from 415,737 participants all aged between 40-69 years was used to examine the effects of fish oil supplements on the clinical course of cardiovascular disease. The findings look good on the surface. “For people with a diagnosis of cardiovascular disease, regular use of fish oil supplements did reduce the risk of transitions from atrial fibrillation to major adverse cardiovascular events, heart failure and death,” Dr Srinivasan explains.

However, if you don’t have cardiac problems, taking regular fish oil might have the opposite effect. The study showed a 5 per cent greater risk of stroke, and a 13 per cent higher risk of developing an irregular heart rhythm. “Regular use of fish oil supplements might actually be a risk factor for atrial fibrillation and stroke among the general population,” Dr Srinivasan notes. The study was observational, so no causal relationship can be drawn, nor did it differentiate between different dosages. “I wouldn’t, in any way, recommend fish oil for atrial fibrillation.” He says. Nor does the NHS, since evidence for their efficacy in preventing heart disease is weak.

Drink honey and lemon for colds: True

The ancient Egyptians, Greeks and Romans all used honey for the treatment of skin ailments. It’s one of the world’s oldest remedies.

But can drinking it with a squeeze of lemon really help ease a cold? Yes, says Lucy Miller, a leading nutritional therapist. Lemon juice is an excellent source of vitamin C which is “key for immune health as it helps stimulate the production of white blood cells that help the body fight infection,” she explains. “There is some evidence that vitamin C can reduce the length of a cold, but in a drink, it would only be present in microscopic amounts.”

Honey’s efficacy as a cough treatment is more compelling.  A lot of research now suggests it is more effective for easing upper respiratory symptoms, especially coughing, than over-the-counter treatments. Drinking hot water, meanwhile, helps clear mucus and ease congestion. In fact, NHS guidance now states that “hot lemon with honey has a similar effect to cough medicines”.

“It helps with hydration, immunity and reduces congestion,” says Miller. “So, if you enjoy it, the next time you have a cold, add a teaspoon of honey to warm water with a squeeze of lemon.” Using raw unfiltered honey, and including the peel (rich in vitamin C and protective flavonoids) may boost its curative powers further still. 

Hot toddy for a cough: False

Whisky, lemon, honey, cinnamon, cloves: thought to originate from India, the hot toddy comes from the Hindi word “tadi”, a drink made from fermented palm sap in the early 1600s, explains Dr Krishna Vakharia, a GP and clinical director at Patient.

“Some of these ingredients provide vitamin C to support the immune system, natural antibacterial and anti-inflammatory properties,” she explains. “The alcohol, however, whilst possibly providing some temporary numbing effect to a sore throat – will eventually lead to harm. In fact, alcohol could lower our immune function and make us more susceptible to illness or worse.”

So, Dr Vakharia suggests skipping the alcohol and having a hot cup of lemon, honey and ginger tea.

Gargle with salt water for sore throats: True

Rooted in the antiseptic properties of salt, “it’s a home remedy that has been used for millennia by the Egyptians, Romans and Greeks,” explains Dr Vikram Murthy, a GP and co-founder of The Murthy Clinic. 

Does it stand up to the standards of modern scientific scrutiny? “Yes it does,” he continues. “It has been proven to reduce pain and inflammation for those with sore throats because it creates an environment where it is difficult for bacteria and viruses to thrive.” In fact, the NHS recommends salt water gargles as a first port of call, to sooth sore throats and shorten their duration. 

“Use up to half a teaspoon of salt in approximately 250ml of water,” Dr Murphy suggests. “You can use cold water or hot water but for a sore throat, warm water may be more beneficial in relieving the soreness. Gargle three times a day and even more often if your sore throat is not being relieved.”

Going out with wet hair causes colds: False but...

This is an old wives’ tale, says Dr Murthy, likely derived from drawing the wrong conclusion from an accurate observation. “You have to be in the presence of the virus to catch a cold, so you cannot catch one simply by having wet hair,” he explains. In essence, you need to breathe in droplets coughed or sneezed into the air by someone who already has a cold. 

That said, don’t ignore the age-old advice entirely. “By having wet hair or being cold, you lower your immune response to fight off infections, and with lower temperatures your body tends to pick up more infections as a result,” Dr Murthy says. “That’s why you are likely to get more coughs and colds in winter when the temperature is lower.” 

So your grandmother’s not entirely wrong – if you are sneezed on by someone cold-riddled, you are less likely to battle it off if you have left the house with wet hair. 

Starve a fever: False

This is, quite simply, a bad idea. “Calories in the form of food are required by the body to build up an effective defence against any infections, so starving yourself could actually be detrimental,” explains Dr Murthy. In fact, when your temperature is high you need more calories, not less, as your metabolism too will be raised. 

“The advice to starve a fever dates back to the time of the Greek physician Hippocrates around 400 BC, when fever was not very well understood and it was thought by starving the sick person you starve the disease,” he explains.

In actual fact, it’s the polar opposite of a good strategy. Instead, “eat well and keep well hydrated,” he advises. “You may not want to eat the food you usually like, but try to eat something that you enjoy or which has high calorie density.”

Chicken soup for all ills: True(ish)

“According to the old wives’ tale, chicken soup is the answer to any ailment due to its nourishing ingredients,” says Miller. Traditionally, the ingredients include bone broth, chicken meat and a host of vegetables like onion, garlic, carrots and celery, all of which have powerful nutritional properties, she explains. 

“Onions and garlic are known for their anti-inflammatory and antiviral properties and they also act as prebiotics to support gut health,” says Miller. “We know that 70 per cent of our immune system resides in the gut, and there is no better food for supporting our gut health than a good bone broth. It’s anti-inflammatory and easy to digest. It also contains electrolytes, such as potassium, phosphorus and chloride and so it’s a good support if you’re dehydrated due to sickness.”

Chicken soup has been shown to have positive effects on the respiratory system according to two studies by the University of Nebraska (first in 1993 and then in 2000). “While it’s not a miracle cure, it’s a perfect go-to for its nutrient dense properties that help support your immune system, while also providing you with that comforting meal that makes you feel better,” she says. Eschew shop-bought, high-salt versions and opt for homemade. Just like Granny would have prescribed.