It can be so confusing - one week a food is bad for your health, the next it's good. We look at the latest thinking on coffee, eggs, salt and oil.
Kiwis love their coffee. Yet many people feel guilty when they reach for that second or third cup. We know that too much can affect sleep quality and that pregnant women should have no more than four cups a day as higher amounts have been linked to stillbirth. We also know coffee can cause heart palpitations and even exacerbate anxiety disorders.
But there is increasing evidence that coffee drinking has a good side.
American journalist Jean Carper, author of 100 Simple Things You Can Do to Prevent Alzheimer's, says coffee is emerging as a tonic for the ageing brain. She notes a Finnish study that found men and women who drank three to five cups a day in middle age were less likely to develop Alzheimer's 20 years later.
The study aimed to analyse links between coffee consumption at midlife and dementia/Alzheimer's disease risk in late life. After an average follow-up of 21 years, 1409 people aged 65 to 79 were reassessed in 1988.
The study concluded that coffee drinkers at midlife had a lower risk of these diseases later in life compared with those drinking no or only little coffee. The lowest risk (65 per cent decreased risk) was found in people who drank three to five cups a day.
Coffee may also have a role in improving movement impairment caused by Parkinson's disease. Canadian research published last year in the journal Neurology showed caffeine could help people who already have the disease. For the study, 61 people with Parkinson's who suffered daytime sleepiness and some motor symptoms were given either a placebo or a pill with 100 milligrams of caffeine twice a day for three weeks, then 200 milligrams twice a day for three weeks - the equivalent of two to four cups of coffee a day.
After six weeks, the half who took the caffeine supplements showed improvement in Parkinson's severity, speed of movement and stiffness.
Carper notes that coffee is an anti-inflammatory that helps block cholesterol in the brain and lower the risks of stroke, depression and diabetes.
However, a recent study by the Western Australian Institute for Medical Research and the University of Western Australia shows the benefits derived from coffee drinking are dose dependent.
Initially, the researchers set out to prove the cardiovascular benefits of coffee, but instead discovered it can worsen obesity and related diseases.
Researchers focused on a compound found in coffee, known as chlorogenic acid (CGA), and found that in high amounts it can make humans fat in areas particularly detrimental to health.
They found that mice given the equivalent of five regular cups of coffee developed double the amount of the dreaded visceral fat - the dangerous type that gathers around the abdomen.
Scrambled, poached or fried? The health benefits derived from an egg depend on your answer. But if we focus on a plain old boiled egg, the health news is good compared with a decade ago.
People with high cholesterol used to be advised to steer away from eating too many eggs, as it was believed that cholesterol in foods raised blood cholesterol levels. However, research has shown that cholesterol is influenced by the saturated and trans fat we eat rather than the naturally occurring cholesterol in foods.
It is the "bad" or saturated fat content in foods such as biscuits, chips, butter and processed and takeaway food that causes cholesterol levels to rise.
Australian Dietary Guidelines now recommend we consume more eggs and that up to seven a week is acceptable. Eggs contain important nutrients including folate, omega 3 fatty acids and arginine (a precursor for nitric oxide, which increases blood flow) and may reduce the risk of cardiovascular disease.
And, they won't make you fat. One egg contains five grams of fat - most of which is the "good", unsaturated fat that you need to be healthy. An egg contains only about 1.5 grams of saturated fat and no trans fat.
Eggs are also a natural source of at least 11 vitamins and minerals and are a high-quality protein.
A University of Sydney study is also investigating the role of eggs in managing type 2 diabetes. Researchers aim to identify the potential health benefits of a high egg diet in pre-diabetics and those with type 2 diabetes. Participants are following a specific high-egg diet (two or more a day for six days a week) or a low-egg regime (fewer than two a week).
Research leader Nick Fuller says: "We are addressing the limited amount of precisely conducted research on eggs in a high-risk population such as type 2 diabetics to clear up misconceptions about how many eggs diabetics can actually have."
Researchers aim to complete the study in six months.
We need salt to survive. It helps our body maintain the correct balance of fluids, in order to transmit nerve impulses and maintain proper muscle function. But we don't need to add salt to our food. We can get enough from what is found naturally in foods by eating a balanced diet. We know that too much salt in some people can cause high blood pressure, putting them at risk of heart disease and stroke.
Salt is made up of two compounds - sodium and chloride. If you choose to add salt, it's better to use the iodised type because of the body and brain's need for iodine. The World Health Organisation says pregnant women need about 66 per cent more iodine than non-pregnant women. It recommends pregnant or breastfeeding women consume 250 micrograms a day as a total daily intake, which is almost impossible to achieve through diet alone.
Most foods are relatively low in iodine, so to ensure more people have enough, WHO and Unicef recommend universal salt iodisation.
Salt does not have naturally occurring iodine in it. Dr John Eden, an endocrinologist at the University of NSW, says: "People should choose the iodine-infused salt; not just women, men too. Men can get goitre if they are lacking in iodine, which is when the thyroid enlarges and can protrude from the neck. You can overdo it, though: if you consume too much you can cause the thyroid to shut down. It's about balance."
Not so long ago it was thought that all oil was bad for us. The well-documented benefits of the Mediterranean diet, with its healthy amounts of olive oil, have taught us that good oils have a place in a healthy diet, and have been linked to reduced levels of obesity, metabolic syndrome and diabetes.
Associate Professor Tim Crowe, from the school of exercise and nutrition sciences at Melbourne's Deakin University, says: "There was a period in the past few decades when a low-fat diet was very much recommended and this involved some restriction of all fats, including oils."
Restriction of fats was related to reducing cholesterol levels and kilojoules.
Further research showed that very-low-fat diets are not always advantageous for weight control and that reducing unsaturated oils is counterproductive to heart health.
Oils are a complex mixture of different fatty acids, including the polyunsaturated omega-3s and omega-6s, monounsaturated and saturated types.
The fats we ingest from oil have important structural roles in maintaining nerve impulse transmission, memory storage, and tissue structure.
Fats are the major component of cell membranes and help in the absorption of fat-soluble vitamins A, D, E and K.
- The Dominion Post
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