Diet vs. drugs – Comparing the effects of diet with leading pharmaceuticals

In 440 B.C., Hippocrates famously said “Let food be thy medicine.” More than 2,000 years later, the evidence to substantiate this statement has never been more robust.

Research has consistently demonstrated that for many health issues, diet can be as effective and sometimes even more so than pharmaceutical treatment options as demonstrated in three prevalent health issues –high blood pressure, high cholesterol and diabetes.

High blood pressure

Ninety per cent of people will develop high blood pressure during their lifetime. This is noteworthy because high blood pressure is the most important risk factor for cardiovascular disease, the leading cause of death worldwide. The most obvious way to lower blood pressure is to reduce dietary sodium intakes. This strategy, which has been utilized since the turn of the 20th century, can decrease systolic blood pressure by seven units (mmHg). Though shy of the 10-to-15-unit reduction that’s achievable with first-line blood pressure medication, lowering sodium is only the first step toward lowering blood pressure.

In medical school, DASH (Dietary Approaches to Stop Hypertension) is taught as an evidence-based dietary approach to lower blood pressure. DASH limits sodium and otherwise largely resembles Canada’s Food Guide from 1992, which was essentially a reasonably balanced diet that, despite criticism, is still superior to the average Western diet. Hence, meta-analyses conservatively estimate that the DASH diet on average lowers systolic blood pressure (the top number) by seven units and diastolic (the bottom number) by three. That being said, results vary. For some, the DASH diet can enable reductions that are equivalent to first-line blood pressure medications. But diet and medications are not mutually exclusive treatment options. One study showed that combining a blood-pressure medication (called Lorsartan) with DASH can nearly double the blood-pressure lowering effect compared to just taking the medication alone.

Despite its acclaim, the DASH diet is not the most potent one for lowering blood pressure. Though strict, plant-based diets – consisting of real, whole, non-processed foods eaten in the absence of meat and dairy products – have been shown to lower systolic blood pressure by 16 units and diastolic by nine. Thus, when it comes to blood pressure, plant-based diets are effectively equivalent to first-line medications.

When it comes to blood pressure, plant-based diets are effectively equivalent to first-line medications.

Consuming a single food or nutrient, like it is medicine,  is rarely the solution to health problems. Instead, as illustrated above, a dietary pattern involving many foods usually offers the greatest benefit. However, when it comes to blood pressure, flaxseed is an exception. Research conducted at the University of Manitoba showed that the daily intake of four tablespoons of ground flaxseed in the absence of any other dietary changes can lower blood pressure by up to 15 systolic and 7 diastolic units. Thus, four tablespoons of flaxseed daily can be as effective as a single blood pressure medication. Of course, when given in combination, blood-pressure meds can have additive effects and lower blood pressure to an even greater degree. Nevertheless, there has never been a study of the additive effects of flaxseed in the context of a plant-based diet.

High cholesterol

High cholesterol, which affects 14 per cent of Canadians, is another risk factor for heart disease, albeit a complicated one because cholesterol levels are only part of the heart-disease risk equation. The first diets for lowering cholesterol focused on the elimination of one nutrient, saturated fat, largely found in dairy products and meat. However, disease prevention is not just about what you’re eating that’s bad for you, it’s equally about what you’re not eating that could be good for you.

Hence, dietary strategies that lower cholesterol via the elimination of harmful foods is only half the story. The introduction of healthful foods can be even more helpful. The Portfolio Diet, developed at the University of Toronto, is based on this premise. It has four components, each of which can lower cholesterol by five to 10 per cent, and when combined can additively lower cholesterol by 30 per cent. Hence, the Portfolio Diet is almost on par with the most effective class of cholesterol lowering medications that lower cholesterol by 20-60 per cent. The four components include: a handful of nuts daily, a hefty amount of plant protein daily (chickpeas, soybeans, lentils), viscous fibers (that can be derived from five servings of vegetables per day alongside oats, beans and lentils) and finally, plant sterols that previously were added to certain fortified foods but currently may only be available in supplement form.


Currently, 6 million Canadians have prediabetes, the intermediate stage whereby blood sugar levels are elevated but not high enough to meet diagnostic criteria for diabetes. A landmark study published over two decades ago in the New England Journal of Medicine showed that when it comes to preventing the progression from prediabetes, a healthy diet combined with exercise is more effective than medications. The dietary approach used in the study, which was conducted in the U.S., had patients eating according to the 1996 U.S. Department of Agriculture food guide with 150 minutes of exercise per week; yet again, the road to disease prevention is just a reasonable, balanced diet along with exercise.

Every year, more than 200,000 Canadians are newly diagnosed with diabetes. A study published this year showed that in the first year after diagnosis, low-carbohydrates diets can induce remission in 77 per cent of patients. This is remarkable considering that there is no medication for reversing diabetes.

Low-carbohydrates diets can induce remission in 77 per cent of diabetes patients.

Making wise carb choices is equally, if not more important than minimizing carbs. In 1981, scientists in Toronto developed the Glycemic Index, a system that ranks carbohydrates according to their blood sugar raising potential. Certain foods, like dessert, baked goods, white rice and white bread are digested quickly and rapidly raise blood-sugar levels. These foods are labelled as “high GI” foods. Meanwhile, other carbs like oats and parboiled rice are digested more slowly and produce a gentler rise in blood sugar and are categorized as “low GI” foods.

Blood-sugar levels, a proxy for diabetes severity, are monitored with a lab test called hemoglobin A1c, which measures how sugar-coated your red blood cells are. Ideally less than 5.6 per cent of red blood cells should be sugar-coated. Prediabetes occurs when greater than 6 per cent of red blood cells are sugar coated, and diabetes is diagnosed when greater than 6.5 per cent are sugar-coated.

Studies have shown that adopting a low-glycemic index diet on average lowers HbA1c by 0.31 per cent. This is slightly superior to low-carb diets that on average lower HbA1c by 0.23 per cent. One study showed that adopting a keto or Mediterranean diet can lower HbA1c by 0.5 per cent. Ultimately, maximum dosing of metformin, the first-line diabetes medication, lowers HbA1c by 1 per cent. Hence, when it comes to lowering blood sugar in patients with a diagnosis of diabetes, medications are more potent than diet, but as mentioned previously, diet is the only thing that can prevent patients from needing the medication in the first place.

In conclusion, as Hippocrates said long ago, food can indeed be as powerful as medication. This isn’t true in every scenario, but for high blood pressure, cholesterol and diabetes, diet offers largely untapped potential to prevent or mitigate many of the leading health issues that afflict millions of Canadians.


Condition Dietary Approach Expected Benefit from Diet Expected benefit from medications
High Blood Pressure Reduction of dietary sodium intakes -7 mmHg systolic blood pressure Single first-line blood pressure medication:


-10-15 mmHg systolic


-8-10 mmHg diastolic

DASH diet -7 mmHg systolic blood pressure

-3 mmHg diastolic blood pressure

Plant-based diet -16 mmHg systolic

-9 mmHg diastolic blood pressure

4 tablespoons of ground flaxseed -15 mm Hg systolic blood pressure

-7 mmHg diastolic blood pressure

High Cholesterol Portfolio Diet 30% reduction of LDL cholesterol Most effective statin medications:


20-60% reduction of LDL cholesterol

Diabetes Prevention Balanced Diet + Exercise 7 people need to adopt this diet to prevent 1 person from developing diabetes 14 people need to take Metformin to prevent 1 person from developing diabetes
Reversing Diabetes Low-Carb Diet -enables remission in 70% of people -there is no pharmaceutical treatment that can reverse diabetes
Managing Diabetes Low Carb Diet -0.23 % reduction in HbA1c -max dose Metformin lowers HbA1c by 1%
  Low GI Diet -0.31 % reduction in HbA1c
  Keto/Mediterranean Diet -0.5 % reduction in HbA1c





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Mary Sco.


Mary Sco. is a family medicine resident at Women’s College Hospital. Prior to medical school, she completed a PhD in nutritional sciences.

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