Last Updated on October 21, 2022 by Michael Joseph
Cardiovascular diseases have no sole causal factor, and genes, various health markers, lifestyle factors, and environmental exposures can all play a role.
However, our habitual diet can affect nutrition-related health markers such as low-density lipoprotein cholesterol (LDL-C).
This article looks at food (and drink) options that lower LDL-C in high-quality human studies.
The article will discuss why each food can lower LDL-C and provide scientific references showing the effect in human clinical trials.
Table of contents
- 1) Psyllium Husk
- 2) Oats
- 3) Soy Protein
- 4) Walnuts
- 5) Almonds
- 6) Tomatoes (and Tomato/Lycopene Products)
- 7) Flaxseeds
- 8) Barley
- 9) Filtered Coffee (Versus Unfiltered)
- 10) Green Tea
- 11) Turmeric/Curcumin
- 12) Avocado
- 13) Hazelnuts
- 14) Unsaturated Oils
- 15) Foods Containing Plant Sterols and Stanols
- Important Notes and Caveats
1) Psyllium Husk
Psyllium husk is made from the ground husks of seeds from a plant called Plantago ovata.
Numerous research has shown that a higher dietary intake of soluble fiber can lower LDL-C.
For instance, a meta-analysis of 67 controlled trials published in the American Journal of Clinical Nutrition found a consistent but modest effect of various soluble fibers on lowering LDL-C (7).
Evidence Supporting Psyllium Husk Lowering LDL-C
- A 2018 meta-analysis and systematic review included 28 randomized controlled trials that assessed the impact of psyllium husk supplementation on LDL-C. The study included participants with and without raised cholesterol levels, and the results found that a median dose of 10.2 grams of psyllium per day lowered LDL-C by a median of 0.33 mmol/L (12.76 mg/dL) (8).
On this note, numerous studies have demonstrated that beta-glucans have an LDL-lowering effect (10).
Evidence Supporting Oats Lowering LDL-C
- A 2022 systematic review and meta-analysis of randomized controlled trials included 59 trials. Across all trials, compared to control diets, individuals supplementing with oats had lower LDL-C by 0.29 mmol/L (11.21 mg/dL) compared to individuals consuming control diets (11).
- In 2016, a systematic review and meta-analysis of randomized controlled trials assessed the effects of beta-glucan from oats on LDL-C. Across 58 trials, a median dose of 3.5 grams per day of beta-glucan lowered LDL-C by 0.19 mmol/L (7.35 mg/dL) (12).
3) Soy Protein
Soy protein exists in various forms, and it is a common ingredient in the food chain, from soy protein powders to whole soybeans and soybean products like tofu.
In 2012, the European Food Safety Authority (EFSA) released a publication noting that there is no established “cause and effect relationship” between soy protein and LDL-C (13).
Evidence Supporting Soy Protein Lowering LDL-C
- Published in June 2022, a systematic review and meta-analysis included forty-two randomized controlled trials to analyze the role of plant compounds in cardiovascular disease prevention. Among these trials, fifteen assessed the impact of soy protein on lipid profiles (cholesterol levels). In these trials, soy protein had a statistically significant effect on lowering LDL-C by a mean of 0.15 mmol/L (5.8 mg/dL) (15).
- A 2021 systematic review and meta-analysis examined the impact of isolated soy protein or soy isoflavone extracts on the lipid profile of postmenopausal women. Overall, including all trials comparing soy protein interventions to a control group, soy protein had a statistically significant but modest effect in lowering LDL-C by 0.05 mmol/L (1.83 mg/dL) (16).
Walnuts are among the most popular tree nut options and contain high levels of polyunsaturated fat.
Per 100 grams, walnuts provide 47.2 grams of polyunsaturated fat (17).
Notably, as established by the ‘Keys equation,’ the diet’s ratio of polyunsaturated to saturated fat can either lower LDL-C (more polyunsaturated) or raise it (more saturated). Each gram of saturated fat is approximately twice as effective at impacting LDL-C levels compared to each gram of polyunsaturated fat (18, 19).
Thus, an ounce serving of walnuts should effectively lower LDL-C since it contains 13.4 grams of polyunsaturated fat and only 1.74 grams of saturated fat (17).
Walnuts are also a rich monounsaturated fat source, which can lower LDL-C when replacing saturated fat.
Evidence Supporting Walnuts Lowering LDL-C
- A 2022 systematic review and meta-analysis of randomized controlled trials examined walnut intake’s effect on biomarkers of metabolic syndrome. Intakes ranged from 28 grams per day to 75 grams per day. Based on data from twelve trials, there was a reduction in LDL-C levels in walnut diets compared to control diets. The mean difference was 5.93 mg/dL (0.15 mmol/L) (20).
- A 2018 systematic review and meta-analysis found that, among twenty-six clinical trials, incorporating walnut-enriched diets lowered LDL-C by a mean of 5.51 mg/dL (0.14 mmol/L) compared to control (21).
Per typical ounce (28.35g) serving, the polyunsaturated to the saturated fat content of almonds is 3.49 grams to 1.08 grams. Thus, we would expect almonds to have an LDL-C-lowering effect.
Evidence Supporting Almonds Lowering LDL-C
- A 2016 systematic review and meta-analysis assessing the effects of almond intake on blood lipid levels included eighteen randomized controlled trials. Across these trials, interventions including almonds lowered LDL-C by a mean of 0.124 mmol/L (4.795 mg/dL) compared to control diets (23).
- In 2015, a systematic review and meta-analysis assessed sixty-one randomized controlled trials to determine the impact of tree nuts on blood lipids. Among these trials, sixteen examined almonds. The study found that tree nut interventions lowered LDL-C by a mean of 4.8 mg/dL (0.124 mmol/L) compared to control diets (24).
6) Tomatoes (and Tomato/Lycopene Products)
Interestingly, research suggests that tomatoes may potentially have an impact on lipid levels.
This effect may be due to the lycopene content of tomatoes, a type of carotenoid found in red-pigmented plant foods (25).
Evidence Supporting Tomatoes Lowering LDL-C
- A 2011 meta-analysis assessed eight studies that tested the effect of lycopene on LDL-C levels. Over these studies, lycopene interventions lowered LDL-C by a mean of 4.63 mg/dL (0.119 mmol/L). However, when looking at only four studies that used a high lycopene dose, defined as a dosage of >25 mg, the results demonstrated a mean 10.35 mg/dL (0.267 mmol/L) reduction in LDL-C (26).
- A 2017 systematic review and meta-analysis assessed the effect of tomato and lycopene supplementation on cardiovascular risk factors. Out of twenty-one studies, six investigated the impact of tomato supplementation on LDL-C. The results demonstrated that tomato supplementation (e.g. fresh tomatoes, juice, soup, tomato paste) significantly lowered LDL-C by a mean of 0.22 mmol/L (8.51 mg/dL) (27).
Flaxseeds are a variety of seed that provides a significant source of fiber and polyunsaturated fatty acids.
Just a tablespoon (10.3g) serving of flaxseeds provides 2.81 grams of fiber and 2.96 grams of polyunsaturated fat (28).
Evidence Supporting Flaxseeds Lowering LDL-C
- An extensive systematic review and dose-response meta-analysis published in 2019 assessed the effect of flaxseed supplementation on the lipid profile. Across sixty-two randomized controlled trials, flaxseed supplementation lowered LDL-C by a mean of 4.206 mg/dL (0.108 mmol/L) (29).
- A recent 2021 systematic review and dose-response meta-analysis of randomized controlled trials assessed the effect of various flaxseed products on patients with high cholesterol. Across twenty-six studies, flaxseed-containing products lowered LDL-C by 6.92 mg/dL (0.178 mmol/L) (30).
Like oats, barley is a significant source of fiber and beta-glucan (31).
Early studies demonstrated that the cholesterol-lowering strength of beta-glucan was identical, whether the source was oats or barley (32).
Evidence Supporting Barley Lowering LDL-C
- A 2016 systematic review and meta-analysis of randomized controlled trials examined the effect of barley beta-glucan on blood lipids. The analysis of fourteen trials demonstrated that a median dose of 6-7 grams of beta-glucan from barley per day lowered LDL-C by 7% (33).
- An earlier systematic review of eight randomized controlled trials, published in 2009, had similar results. This review found that barley intervention diets significantly lowered LDL-C by a mean of 10.02 mg/dL (0.259 mmol/L) compared to the control (34).
9) Filtered Coffee (Versus Unfiltered)
Interestingly, coffee intake can influence LDL-C levels depending on how it is made.
Coffee has a potential LDL-C-raising effect due to its content of oily compounds called diterpenes. The most well-known diterpenes are cafestol and kahweol (33).
Instant coffee is similar to filtered coffee in that it contains very low levels of diterpenes.
Evidence Supporting Filtered Coffee Lowering LDL-C Compared To Unfiltered Coffee
- A meta-analysis of fourteen randomized controlled trials examined coffee consumption’s effect on blood lipids. The results demonstrated that coffee intake has a dose-response impact on raising LDL-C. In this regard, six cups of coffee per day significantly increased LDL cholesterol by 6.5 mg/dL (0.168 mmol/L). However, further analysis of the trials found that filtered coffee had minimal effects on cholesterol levels, and unfiltered coffee led to significant LDL-C increases (36).
10) Green Tea
Interestingly, the polyphenolic compounds in green tea can have various effects on the body. Among these compounds, it is thought that epigallocatechin gallate may decrease levels of LDL-C (38).
Evidence Supporting Green Tea Lowering LDL-C
- A 2022 umbrella review of thirteen meta-analyses assessed the effect of green tea on various health markers. Four of these meta-analyses investigated the effect of green tea intake on levels of LDL-C. The review found that these meta-analyses offered ‘moderate quality evidence’ that green tea lowered LDL-C levels by a mean of 4.31 mg/dL (0.108 mmol/L) (39).
- A 2020 systematic review and meta-analysis published in Nutrition Journal examined the effect of green tea on blood lipids. When assessing thirty-one randomized controlled trials, 29 comparisons looked at the impact of green tea on LDL-C. These trials showed a mean 4.55 mg/dL (0.117 mmol/L) decrease in LDL-C in green tea interventions compared to the control (40).
However, it is essential to note that not all research shows the same results regarding green tea and LDL-C. For instance, a systematic review and meta-analysis published in 2020 included fourteen randomized controlled trials looking at short-term green tea intake and cardiovascular risk markers (41).
The review results demonstrated no significant effect of green tea on LDL-C. However, the authors noted that the results weren’t statistically significant, likely due to the short duration of the included trials.
Turmeric is a common spice used in cooking and is particularly popular in South Asian cuisine.
Some research suggests that turmeric intake may decrease LDL-C levels, likely due to a yellow-pigmented compound it contains called curcumin (42).
Evidence Supporting Turmeric Lowering LDL-C
- A 2022 systematic review and meta-analysis examined the effect of turmeric and curcumin on lipid profiles and blood glucose in participants with type 2 diabetes. Based on results from nine randomized controlled trials, turmeric/curcumin groups lowered LDL-C by a mean of 4.01 mg/dL (0.103 mmol/L) compared to placebo. It is important to note that these results were not statistically significant. However, the authors note that a limitation of the results was that some trials had small sample sizes and short durations. They added that turmeric/curcumin may have clinically significant effects as a simple intervention and that large randomized controlled trials are required to confirm this (43).
An earlier 2017 systematic review and meta-analysis of randomized controlled trials showed similar results (44).
Avocado is a popular oily fruit rich in fiber and unsaturated fatty acids.
A typical avocado provides 3.2 grams of saturated fat, 14.7 grams of monounsaturated fat, and 2.73 grams of polyunsaturated fat (45).
Evidence Supporting Avocados Lowering LDL-C
- A previous 2018 systematic review and meta-analysis found that avocados lowered LDL-C levels by 3.54 mg/dL (0.091 mmol/L), but the results were not statistically significant. However, the authors noted that the small sample sizes (249 participants over ten trials) and short durations in the included studies were a limitation of the review, concluding that future long-term trials were required (46).
- A recent large randomized trial published in the Journal of the American Heart Association in July 2022 looked at the effects of eating one avocado daily for six months. 503 participants were assigned to consume their habitual diet, while five hundred five 505 participants supplemented their diet with one avocado per day. After six months, the avocado group lowered their baseline LDL-C levels by 2.9 mg/dL (0.075 mmol/L) more than the control group (47).
Hazelnuts are one of the most popular tree nuts.
As well as being high in fiber, hazelnuts provide a significant amount of monounsaturated and polyunsaturated fat (48).
Evidence Supporting Hazelnuts Lowering LDL-C
- A systematic review and meta-analysis published in 2016 assessed the effects of hazelnut intake on blood lipids and body weight. The analysis included nine clinical trials in which participants consumed a mean dose of 38.7 grams of hazelnuts per day for a mean of 74.7 days. Among these meta-analyzed trials, four were randomized controlled trials. The hazelnut groups had an overall mean reduction in LDL-C of 0.150 mmol/L (5.8 mg/dL) compared to the control groups (49).
14) Unsaturated Oils
Due to their high ratio of unsaturated fats to saturated fat, various unsaturated oils can lower LDL-C.
Research shows this effect with oils such as Canola (rapeseed) oil, olive oil, sunflower oil, and soybean oil (50).
Evidence Supporting Unsaturated Oils Lowering LDL-C
- A 2022 systematic review and meta-analysis of randomized controlled trials examined the effect of canola oil and olive oil on blood lipids. Directly contrasting the two, canola oil lowered LDL-C by 6.13 mg/dL (0.158 mmol/L) more than olive oil over thirteen trials. Canola oil contains more polyunsaturated to saturated fat than olive oil (51).
- A 2020 systematic review and meta-analysis conducted a dose-response analysis of Canola oil’s effects on cardiovascular risk factors. Over ten trials comparing the effect of Canola oil and saturated fats (such as palm oil and butter), Canola lowered LDL-C by a mean of 0.49 mmol/L (18.95 mg/dL) compared to saturated fats. Canola also lowered LDL-C compared to olive and sunflower oils by a more modest amount (52).
- A 2018 systematic review and meta-analysis compared the effects of different oils/fats on blood lipids. Among the review’s various findings, each 10% of dietary calories from butter replaced by predominantly unsaturated oils led to a drop in LDL-C by between 0.31 mmol/L (11.98 mg/dL) and 0.22 mmol/L (8.50 mg/dL), depending on the specific oil (50).
15) Foods Containing Plant Sterols and Stanols
Plant sterols, also known as phytosterols, are components of plants that structurally resemble cholesterol (51).
These plant sterols have been shown to lower LDL-C by as much as 10% at intake levels of 2 grams per day (52).
Foods High In Plant Sterols
According to published data, here are some of the most plant sterol-rich foods alongside their plant sterol content per 100 grams (53):
- Corn oil: 682-952 mg
- Canola (rapeseed) oil: 250-767 mg
- Soybean oil: 221-238 mg
- Sunflower oil: 263-376 mg
- Olive oil: 144-193 mg
- Corn: 66-178 mg
- Rye: 71-113 mg
- Wheat: 45-83 mg
- Barley: 80 mg
- Millet: 77 mg
- Avocado: 75 mg
- Rice: 72 mg
- Passion fruit: 44 mg
- Oats: 35-61 mg
- Broccoli: 39 mg
- Raspberries: 27 mg
- Orange: 24 mg
- Cauliflower: 18-40 mg
- Apple: 12-18 mg
- Banana: 12-16 mg
- Carrot: 12-16 mg
- Lettuce: 9-17 mg
Important Notes and Caveats
The foods mentioned in this guide have evidence from randomized controlled trials and systematic reviews supporting their LDL-lowering effects.
However, it is important to note that there are several nuances to this topic area:
- Whether or not a particular food lowers LDL-C will depend on the comparator. For example, does olive oil lower LDL-C? The most accurate answer should always start with “compared to what?” For example, compared to butter, olive oil should lower LDL-C. Yet compared to Canola oil, it would raise it (51).
- The healthfulness of a particular food does not solely depend on its effect on LDL-C. Other components of the food and its nutrient provision also need consideration. For instance, oily fish is consistently associated with health benefits despite increasing LDL-C levels compared to lean red meat and plant protein (54).
- The overall diet matters most for health markers like LDL-C rather than individual food choices. However, no foods need to be avoided entirely. Instead, the habitual mix and ratio of fats, fiber, carbohydrates, and food choices play the most significant role in determining diet-related health markers.
For more information on nutritional topics, see these guides.