Knowing your family history can empower you to make crucial diet and lifestyle changes to protect your long-term health.
Check your family tree closely and you will probably find at least one major illness lurking in the branches. But does this automatically put you at high risk of developing it, too?
A condition is suspected to be genetic if it crops up more often than you would expect by chance. That’s generally two or more blood relatives with the same disease, especially if they’re diagnosed before the age of 50.
“We’re finding more and more illnesses — from cancer to diabetes — have a genetic element, so your family’s health history is certainly crucial when it comes to predicting your own future health,” says Dr Anand Saggar, a consultant in clinical genetics. “I’d advise everybody to draw a simple family health tree so they can spot any recurring trends.
“But don’t panic!” says Dr Saggar. “Even if you discover you carry a particular genetic mutation, you’ve only inherited a susceptibility to developing that disease — it doesn’t make it inevitable. Most diseases are triggered by a complex interaction of genes and lifestyle.”
Fortunately, that interaction means there’s plenty you can do to reduce your risk. Here are some of the ways you can minimise your risk of developing common medical conditions that often run in families.
Type 2 diabetes
You’re more likely to develop type 2 diabetes if a parent or sibling has it, compared to someone with no family history. This tendency is partly due to children learning poor dietary habits and inactivity from their parents. But there is also a genetic basis. Generally, if a parent had type 2 diabetes before age 50, your risk of developing type 2 diabetes is one in seven, reducing to one in 13 if they developed it after age 50. So if there’s diabetes in your family, talk to your doctor about having a blood glucose test.
Also keep an eye out for the classic symptoms of tiredness, extreme thirst and the urge to urinate more frequently. On the plus side, type 2 diabetes can usually be prevented with certain lifestyle changes to help reduce your risk. Analysis by the American-based Diabetes Prevention Program Research Group found lifestyle interventions reduced the incidence of type 2 diabetes by 58 per cent, while a comparative group on the drug Metformin reduced their incidence by only 31 percent.
Reduce your risk
Regardless of your genetic make-up, carrying too much weight is by far the biggest risk factor for type 2 diabetes. A 2010 study in Sweden found a high body nass index (BMI) in men was the strongest predictor of who would go on to develop diabetes 10 years later, regardless of other factors. The good news is that a small change to your weight can make a big difference, even for people who already have pre-diabetes (impaired fasting glucose or impaired glucose tolerance).
If you have prediabetes, losing five to 10 per cent of your current body weight could prevent type 2 diabetes in nearly six out of 10 people.
Many studies suggest regular exercise reduces the risk of diabetes by helping your body deal with glucose in your blood more effectively — whatever your weight. And just eight minutes a week of intensive activity may be enough, according to a recent study published in BMC Endocrine Disorders. The study found in men, short bursts of high-intensity exercise (four to six 30-second bursts of fast cycling) improved insulin sensitivity (or the body’s ability to control blood glucose) by nearly a quarter. If high intensity exercise is not your thing, aim for at least 150 minutes of moderate intensity exercise each week.
For more advice, visit www.diabetes.org.nz.
If a close relative younger than 60 has had a heart attack or a stroke you may have inherited a higher risk of the same. There are also many other factors that raise your risk of heart attack or stroke, including high cholesterol or blood pressure, being overweight, poor diet and being inactive. “One inherited condition that raises your risk substantially is Familial Hypercholesterolaemia (FH) – a gene alteration that causes very high cholesterol regardless of how healthy your diet is,” explains Dr Saggar. While there is no screening for FH in New Zealand, it’s estimated 10,500 people may be affected, but up to 10,000 affected people have not been diagnosed and are at risk of developing premature cardiovascular disease.
Reduce your risk
Know your numbers
“Everybody should ask their GP to check their cholesterol and blood pressure,” advises Dr Saggar, “especially if there’s heart disease in your family tree.” If your cholesterol is high, you will be encouraged to make changes to your diet and exercise routine. You may also be prescribed medication to lower your cholesterol.
Cut out the bad stuff
Giving up smoking, losing excess weight and exercising regularly (at least 30 minutes on most days of the week) are important for lowering both cholesterol and blood pressure. It’s also essential to eat a ‘heart-healthy’ diet, so cut down on saturated fat and salt from processed foods, butter, cream and fatty meat. Instead, choose a balanced diet with vegetables, fruit, legumes, whole grains and heart-healthy fats from olive oil, nuts and oily fish.
Slash work stress
There’s increasing evidence that stress has a damaging effect on our hearts. One study from Denmark found women who described their job pressure as ‘much too high’ had a 50 per cent higher risk of ischaemic heart disease (restricted blood flow to the heart). Even those who only considered it ‘a little too high’ had a 25 per cent increased risk. So whether you enjoy yoga or yachting, it’s important to factor in some downtime for the sake of your health.
If you only do one thing to cut your risk – lose excess weight
The risk of many health conditions is increased when you are carrying extra weight. The 2007 World Cancer Research Fund ‘Diet and Cancer Report’ identified obesity as a cause of a number of common cancers, as well as of other diseases.
For more advice, visit www.heartfoundation.org.nz.
Breast and ovarian cancer
The good news is only around five per cent of cases of breast cancer and ovarian cancer are genetically linked. In these instances, the cancer is caused by an inherited ‘faulty’ gene, specifically two genes called BRCA1 and BRCA2, that can be passed on from either parent. If you have two or more close relatives on the same side of the family who have been diagnosed with either cancer then this may be the reason. Women carrying these mutations have a higher risk of breast cancer and of ovarian cancer. However, more common reasons cancer may run in the family are simply by chance or common exposure to risk factors such as diet.
Reduce your risk
Review your diet
Changing to a healthier diet may prevent as many as a quarter of breast cancer cases. Make sure you include lots of fibre from vegetables, fruit and whole grains, cut down on saturated fats found in fatty meats, full-fat dairy and processed foods and reduce the amount of alcohol you drink. Even small amounts of alcohol increase breast cancer risk so if you do decide to drink, aim to limit it to no more than one standard drink a day. A sedentary lifestyle and carrying excess body fat also increases our risk for post-menopausal breast cancer so don’t forget the exercise.
Breastfeed your baby
If you give birth, breastfeeding your baby lowers your risk of developing both pre and post-menopausal breast cancers.
Talk to your health professional
If you have a strong family history of either cancer, your health professional will be able to give you more personalised advice, refer you for genetic testing, or to a family cancer centre to discuss your options about reducing the risk of developing the disease.
For more information, visit www.cancernz.org.nz
New Zealand has one of the highest rates of bowel cancer in the world: overall we have around a one in 23 chance of developing bowel cancer by the time we reach 75 years old, and family history is an important factor. Your risk of developing bowel cancer is increased if you have at least one first-degree relative (parent, sibling or child) diagnosed at 55 years or older. Your risk is further increased if you have a first-degree relative diagnosed younger than 55 years old or two first-degree relatives diagnosed at any age.
Hereditary conditions called familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (also called Lynch syndrome) are responsible for about five per cent of cases of bowel cancer. If bowel cancer runs in your family, or you know you have either of these hereditary conditions in your family, it’s important to talk to your GP about regular screenings to pick up warning signs as early as possible.
Reduce your risk
Know the symptoms
Look out for any change in your bowel habits, especially diarrhoea that lasts longer than a few days or any blood in your stools. See your GP immediately if you notice either.
Go for whole grain and high fibre
Significant evidence shows high-fibre diets are associated with a lower risk of bowel cancer. This means eating plenty of vegetables, fruits, legumes and, in particular, whole grains and cereals.
A review of 25 different studies published in the British Medical Journal found three serves of wholegrain foods each day can reduce the risk of bowel cancer by 20 per cent.
The suggested dietary target for fibre intake is 38g for men and 28g for women, higher than the adequate intakes often quoted at 30g and 25g respectively.
Choose your protein wisely
According to the World Cancer Research Fund, eating more than 500g a week of cooked red meat, and especially processed meat (such as bacon, ham, salami and sausages), increases your risk of bowel cancer. A study published in Archives of Internal Medicine found replacing just one serving of red meat with fish, chicken, low-fat dairy or wholegrain foods could reduce the risk of dying from bowel cancer by seven to 19 per cent. So stick to the recommendations of eating red meat three times a week and opt for poultry, fish and legumes more often instead.
Boost your vitamin D
Having high blood levels of vitamin D is linked to a 40 per cent lower risk of bowel cancer, according to a study published in the British Medical Journal. Most of our vitamin D is made by exposing our skin to sunlight so it’s worth ensuring you spend a few minutes in the sun each day during summer (early in the morning or late in the day when the sun is less fierce), or a few hours during winter, particularly if you live in the south. Although you can’t meet your vitamin D needs through food alone, you can also choose to eat more vitamin D-rich foods. Try to include oily fish such as salmon, sardines, mackerel and herring, eggs, reduced-fat dairy, and some other foods that are fortified with vitamin D.
For more advice, visit www.cancernz.org.nz
The bottom line
Knowing about your family history means you can do more to protect yourself and help reduce your risk of health conditions, ranging from different types of cancer to heart disease. Having this knowledge gives you the tools to make healthy lifestyle choices that will have a positive impact on your future health — so you can lead the healthiest life you possibly can!
Emerging science: The gene-diet link
Understanding the connection between genes and food has led to new areas of research and treatment called nutrigenomics and nutrigenetics. In the same way your genes may predispose you to certain illnesses, they can also play an important role in how well your body handles particular foods or nutrients. Genetic variation is one reason certain diets work for some but not others. New research has focused on the possibility of designing diets based on your specific genetic make-up.
While we are not aware of anyone offering the tests here, other than for research purposes, we could see this in the future. A sample of DNA (usually from saliva) can be tested for variations in our genes that may play a role in how our bodies respond to the food we eat. Based on these results, an eating plan could be recommended in the hope of reducing our risk of health problems.
The research team at Nutrigenomics New Zealand are focusing their research on the inter-relationship between food, food components, autoimmune diseases and gut health. Their first target is Crohn’s disease but their experience in this condition is applicable to other autoimmune diseases such as psoriasis, rheumatoid arthritis, ankylosing spondylitis, eczema and asthma. This is an exciting area of research we’re bound to be hearing more about. Watch this space.