Are we getting to the heart of heart health?
Is heart health is more than just cholesterol?Picture: iStock
Dr. Nick Norwitz’s 1.27m Facebook followers hail him as a leading voice in metabolic health. Detractors call him “a cholesterol denier”. But the 30-year-old clinical researcher, from Boston, who graduated from Oxford with a PhD in metabolism and from Harvard with a medical degree, sees himself as a health educator who wants to empower patients.
Norwitz says: “I try to make people aware of the bigger picture when it comes to health, so they can make smart decisions and become leaders of their own healthcare journeys, with doctors as their guides.”
One of his most controversial claims is that the medical consensus on cholesterol is outdated. He believes doctors focus too much on LDL cholesterol and not enough on an individualised cardiovascular risk assessment based on arterial plaque, metabolic health, and other factors.
Personal health problems prompted Norwitz to change his thinking about cholesterol. He was diagnosed with ulcerative colitis at 22 and spent a year “suffering from up to 12 bouts of bloody diarrhoea every day”.
He tried experimental therapies until the ketogenic diet helped. “This diet — which is high in fat, moderate in protein, and low in carbohydrates — turned my life around,” says Norwitz. “I went from being very ill to full remission.”
Unfortunately, the diet also increased his cholesterol, and his LDL shot up from normal levels of between 2 and 2.3 millimoles per litre (mmol/L) to 15mmol/L.
As a medical student, he understood the implications and worried that in saving his colon he would damage his heart.
Cholesterol is an essential form of fat transported in our blood by particles, called lipoproteins. There are two types of lipoprotein: HDL (high-density lipoprotein), and LDL (low-density lipoprotein), the one that skyrocketed for Norwitz.
“Problems can occur when cholesterol levels, particularly LDL levels, in the blood get too high,” says Dr Róisín Colleran, a consultant cardiologist with the Mater Private Network in Dublin. “It can lead to cholesterol being deposited in our arteries, narrowing, and even blocking them over time, which increases the risk of cardiovascular disease (CVD), heart attack, and stroke.”
About 6,000 heart attacks, 7,500 strokes, and 9,000 deaths from CVD are recorded in Ireland annually, and the medical consensus is that LDL levels contribute. For example, a paper published by the European Atherosclerosis Society in 2017 “unequivocally” declared that high levels of LDL caused CVD.
Such findings are why doctors advise keeping total cholesterol under 5mmol/L and LDL under three.
Heart attack risk?
Norwitz, because of his LDL level of 15, was told that he was at risk of “having a heart attack by 30”.
Seven years after receiving that warning, he takes issue with the European Atherosclerosis Society. “Oxygen is necessary for fire, but oxygen alone does not cause fire,” he says, challenging the established association between high LDL readings and heart disease.
“By the same token, high LDL cholesterol can increase disease risk, but not everyone with high LDL becomes ill.”
He wonders whether high LDL alone prompts some doctors to prescribe statins unnecessarily.
More than 200m people worldwide take cholesterol-lowering drugs, while data from the drug reimbursement scheme shows that approximately 520,000 people in Ireland are prescribed them.
Norwitz does not want to cause alarm. “I’d never say statins are bad, but, like most drugs, they aren’t completely safe,” he says. “They have side effects, such as muscle pain and weakness, increased blood sugar, and risk of diabetes. In the case of people who are overweight and have high blood pressure and high inflammation markers, statins may be a reasonable choice. But in the case of people who are otherwise metabolically healthy, the risks may be greater than the benefits.”
His own case provides an extreme example. When testing showed he was healthy apart from his cholesterol score, he opted to “watch and wait”. He continued following the ketogenic diet. He didn’t take medication. But he did take regular tests.
A cardiac scan seven years later found that, despite consistently high LDL, there was no evidence of plaque in his arteries. He published a paper earlier this year to highlight how his case shows the limits of our understanding of CVD.
“LDL is not the whole story,” Norwitz says. “I’ve had high LDL for seven years and have no signs of CVD. Yet people with low LDL can develop plaque and CVD. We need to investigate further and take a broader perspective.”
The health factors he urges doctors to consider include blood pressure, triglyceride levels, blood sugar, and obesity. “High LDL should be taken far more seriously in someone with high blood pressure and blood sugar and a high body mass index than in someone with low blood pressure, blood sugar, and BMI,” he says.
Insulin resistance is another significant factor. A 2021 study of data involving 28,024 women found that “the CVD risk associated with insulin resistance was greater than the CVD risk associated with high LDL cholesterol”, Norwitz says.
Insulin resistance can culminate in diabetes, but early signs can be detected by testing for insulin and triglyceride levels in the blood after an overnight fast.
Norwitz believes low-carbohydrate diets, like the ketogenic diet, can help counter insulin resistance.
He points to a recent US study as evidence of its potential to improve cardiovascular and metabolic health in people with obesity and insulin resistance.
The 55 participants, all of whom had metabolically unhealthy obesity, were divided into three groups and assigned one of three diets for six months: a ketogenic diet, a Mediterranean diet or a low-fat, plant-forward diet.
The results? LDL cholesterol fell on the ketogenic diet just as much as on the plant-based diet. The ketogenic diet also led to greater improvements in insulin resistance, fatty liver, and inflammation.
This finding ties in with Norwitz’s overall message: Dietary inputs, just like other aspects of health, don’t operate in a vacuum.
“Your starting physiology, including body composition and metabolic state, can influence how your biomarkers respond to interventions,” he says. “We should stop asking, ‘What’s the healthiest diet?’ And start asking, ‘What’s the healthiest diet for me?’ It’s the same with medications, like statins.
“Rather than blanket prescribing them for high LDL, doctors should look at the broader health picture and prescribe accordingly.”
His advice to anyone concerned about cholesterol is to engage with their doctor. “Ask about your other risk factors and request a cardiac scan to check for plaque. If statins are suggested, ask if there are other options. None of this is about [arguing] with your doctor. It’s about making you an active participant in your own health.”
Case-by-case treatment
Norwitz makes a strong case for an individualised approach to treating high LDL. However, Colleran challenges his claim that cardiologists focus exclusively on LDL, saying they “consider the interplay of different risk factors, including blood pressure, whether someone has diabetes, and if they are a smoker”.
Cardiologists, she adds, also look beyond LDL to other particles in the blood, such as lipoprotein(a) and Apo lipoprotein B (ApoB), both of which make it more likely that LDL in the blood will form plaque.
“Testing for these allows doctors to better assess a patient’s risk and recommend next steps,” she says.
GPs follow a similar process to cardiologists. According to Dr Eamonn O’Shea, a Galway-based GP and cardiovascular clinical lead with the Irish College of GPs, “In the vast majority of cases, decisions on treatment are based on an overall cardiac risk assessment, rather than LDL levels alone.
“A GP typically discusses lifestyle issues, including diet, exercise, smoking, and alcohol intake, as well as the person’s medical history and that of their family. Weight, height, blood pressure, renal function, and diabetes status are also assessed, and all these factors are included in cardiovascular risk-prediction tools that estimate the person’s risk of having a heart attack or stroke in the future.”
For those considered high risk, the next step is to help them address the modifiable factors that impact cardiovascular health. “We repeat the measurements, including LDL cholesterol, after three to six months,” says O’Shea. “If they remain in the high-risk zone, intervention with a statin or other cholesterol-lowering drug will then be discussed.”
The protocol is slightly different in the case of the 5% of the population who have exceptionally high levels of LDL (which is defined as more than 5mmol/L). O’Shea says that if this group can’t reduce their cholesterol by lifestyle measures, “the European Society of Cardiology guidelines suggest considering drug therapy, even in the absence of other risk factors. These very high levels can be associated with rare genetic causes of high cholesterol, such as familial hypercholesterolaemia, which is a significant cause of premature heart disease.”
When it comes to Norwitz’s claim that insulin resistance is a major factor in heart health, Colleran agrees. However, she doesn’t agree with his endorsement of the ketogenic diet.
“I worry about people increasing their intake of saturated animal fats,” she says. “I also worry that these diets eliminate fibre-rich, cardioprotective fruits, vegetables, and grains. I recommend the Mediterranean diet, instead.”
Despite their points of difference, Colleran supports Norwitz’s goal to inform patients.
“Start by knowing your numbers,” she says. “Get your blood pressure, cholesterol and blood sugars tested regularly, and if there’s cause for concern, take steps by eating a healthy, balanced diet, exercising, and maintaining a healthy weight. Quit smoking and prioritise sleep.
“CVD is 90% preventable. We should all be proactive about heart health.”
Keeping your cholesterol down
Taking medication is one way to reduce cholesterol. It is typically prescribed when all other options have failed to be effective.
Here are the practical lifestyle changes the Irish Heart Foundation recommends we make if we want to maximise our chances of lowering cholesterol without the need for drugs like statins.
1. Maintain a healthy body weight. Being overweight puts pressure on your heart because it has to work harder to pump blood around your body.
2. Prioritise physical activity. You should aim for a minimum of 30 minutes of physical activity a day for five days a week.
3. Eat fish twice a week, including one oily fish such as salmon or mackerel.
4. Eat more fruit and vegetables.
5. When choosing your carbohydrates, opt for wholegrain varieties of cereals, breads, pasta and rice and leave the skin on jacket potatoes.
6. Choose lean forms of protein like skinless chicken or turkey breast, low-fat cuts of beef, white fish, and shellfish.
7. Eat fewer foods from the top shelf of the food pyramid. These include cakes, biscuits, sweets, chocolate, crisps and other savoury snacks and ice cream as well as processed treats with added sugars and fats.
8. Use healthy cooking methods such as grilling and oven baking instead of frying.
9. If you smoke, try to stop.
10. Keep your alcohol consumption within the recommended weekly limits of 11 standard drinks for women and 17 standard drinks for men.
11. Try to manage stress levels by taking time out for yourself during the working day and throughout the week. Schedule activities that you find relaxing during this time.
12. Continue getting your blood pressure and cholesterol checked regularly by your doctor.
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