Written by Gianina Padula. Medically reviewed by Diana Licalzi, MS, RD, CDE
When you think about protein, what comes to mind? For most, it may be something they consume only to build muscle; for others, perhaps something to keep them full. But did you know that the source of protein may have more of an impact on your health than you think? Specifically, choosing plant proteins over animal proteins makes a drastic difference. Replacing meat with plant-based sources of protein correlates with better heart health, better cholesterol and body weight management, and a lower overall incidence of chronic disease — even after fully adjusting for other lifestyle factors [1,4].
Protein Sources Provide Different Types of Fat
According to a 2017 review by the Physicians Committee of 49 studies comparing vegan diets with omnivorous diets and their effects on plasma lipids (cholesterol), plant-based diets significantly lowered total cholesterol levels compared to diets including meat [9].
Animal proteins, especially red meat, contain significant amounts of saturated fat and cholesterol. Although new research has suggested that the amount of cholesterol in food does not directly correlate with cholesterol levels in the body, these levels are profoundly affected by dietary intake of saturated and trans fats [7].
There are two types of cholesterol in our bodies: high-density lipoprotein (HDL) and low-density lipoprotein (LDL). HDL is considered to be our body’s “good” cholesterol, while LDL is considered our “bad” cholesterol. The overconsumption of saturated fats can lead to elevated LDL levels [7].
On the other hand, plant proteins are low in saturated fat, cholesterol-free, and high in fiber; these characteristics all work to lower LDL levels [3]. Since our body produces all of the cholesterol it needs, there is no reason to be consuming excess cholesterol or saturated fat in one’s diet.
How Protein and Fiber Impact Type 2 Diabetes
Plant-based diets may both prevent and reverse type 2 diabetes. A 2018 study assessing the risk of pre- and type 2 diabetes found that plant proteins lowered insulin resistance [2]. Highly saturated fat foods, on the contrary, such as animal protein, are associated with higher insulin resistance [8]. High insulin resistance has a direct correlation with type 2 diabetes risk, so it is important for prediabetics and those living with type 2 diabetes to steer clear of foods that lower insulin sensitivity.
As mentioned above, diets high in fiber come with their own benefits. Specific to diabetes, soluble fiber helps slow sugar absorption, leading to better blood sugar control [3]. Additionally, high-fiber foods are associated with reduced blood pressure and inflammation [3].
In a study comparing a high-fiber diet with a moderate-fiber diet in patients with type 2 diabetes, the high-fiber diet resulted in better blood glucose control and fewer insulin spikes (shown above) [10]. Participants on the high-fiber diet also showed a significantly lower total cholesterol and triglyceride concentration than their counterparts [10].
Do Plant Proteins Need to be Combined?
Switching to a plant-based diet raises many questions. Some of these include whether foods need to be combined to make a “complete protein” and how to prepare new protein sources.
A food source is considered a complete protein when it contains an adequate amount of all nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine [6]. Essential amino acids must be consumed via our diets because our bodies cannot produce them. It was once believed that plant-based proteins needed to be paired with a grain to be considered complete proteins. This was because plants were thought to be lacking in one or more essential amino acids, and the amino acids in grains would provide those that were missing.
This myth has since been debunked. In his video titled “The Protein Combining Myth,” Dr. Michael Greger shows that this antiquated belief originated from an article with no scientific evidence behind it [5]. In fact, it was largely spread in a 1975 issue of Vogue [5]. Despite the claim being refuted decades ago, it continued to be included in medicinal studies, including publications by the American Heart Association [5].
This led to a widespread misunderstanding and judgment of plant-based diets. This myth is invalid because, in actuality, plants contain all nine essential amino acids. Additionally, our bodies contain pools of amino acids that we can draw on to supplement those in our foods. The essential amino acids in meat originate from plants that are consumed by these animals [5]. We can therefore consume the same amounts of amino acids that meat offers through a plant-based diet alone.
Food prep: Where do I start?
When it comes to learning about the preparation of plant-based proteins, these ingredients can be more versatile than you think. Beans, quinoa, tofu, nuts, and seeds are just a handful of options available. You can use them in an array of ethnic dishes, fit them into any meal of the day, and combine them with spices and herbs to enhance the flavors.
References:
[1] Virtanen et al. (2017). Intake of different dietary proteins and risk of type 2 diabetes in men: The Kuopio Ischaemic Heart Disease Risk Factor Study. British Journal of Nutrition.
[2] Chen et al. (2018). Plant versus animal based diets and insulin resistance, prediabetes and type 2 diabetes: the Rotterdam Study. European Journal of Epidemiology.
[3] Mayo Clinic Staff (2025). Dietary fiber: Essential for a healthy diet. Mayo Clinic.
[4] Richter et al. (2015). Plant protein and animal proteins: do they differentially affect cardiovascular disease risk? Advances in Nutrition.
[5] Greger M. (2013). The Protein Combining Myth. NutritionFacts.org.
[6] U.S. National Library of Medicine. (2025). Dietary fiber. MedlinePlus.
[7] Centers for Disease Control and Prevention. (2024). Cholesterol Myths and Facts. CDC.
[8] Cho C. (2019). Saturated Fat: An Enemy of Type 2 Diabetes Control? WellRx.
[9] Yokoyama et al. (2017). Vegetarian diets and glycemic control in diabetes: a systematic review and meta-analysis. Nutrition Reviews.
[10] Chandalia et al. (2000). Beneficial Effects of High Dietary Fiber Intake in Patients with Type 2 Diabetes Mellitus. New England Journal of Medicine.
Diana is a nationally recognized Registered Dietitian and Certified Diabetes Care and Education Specialist (CDCES), and holds a Master’s degree in Nutrition Science and Policy from the Tufts Friedman School of Nutrition. She received her education and dietetics training from Villanova University, Tufts University, and UC San Diego Health. Diana has over 8 years of experience working in the field of type 2 diabetes.
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