Cholesterol is a waxy, fat-like substance found in all cells of the body. It is an essential component for many functions in the body, but having high cholesterol levels, especially “bad” LDL cholesterol, can increase the risk for heart disease and stroke. Dietary and lifestyle changes are often recommended as the first line of defense against high cholesterol, before prescription medications are used. Some research has suggested that getting enough of the mineral zinc through diet or supplements may help lower cholesterol levels. Here is an overview of the evidence on whether zinc may affect cholesterol.
What is cholesterol?
Cholesterol is a steroid that is produced in the liver and absorbed from food sources. The body uses cholesterol to:
– Build and maintain cell membranes
– Produce certain hormones like estrogen and testosterone
– Help metabolize fat-soluble vitamins like vitamins A, D, E, and K
– Produce compounds that aid in fat digestion
There are a few key types of cholesterol:
– Low-density lipoprotein (LDL) – Also called “bad” cholesterol, LDL makes up 60-70% of total cholesterol. High levels of LDL can lead to a buildup of cholesterol in arteries.
– High-density lipoprotein (HDL) – Often called “good” cholesterol, HDL makes up 20-30% of total cholesterol. It carries cholesterol from other parts of the body back to the liver for removal. Higher levels of HDL are associated with lower risk of heart disease.
– Triglycerides – The main form of fat in the body. Excess calories, alcohol, or sugar in the diet can increase triglyceride levels.
– Total cholesterol – This is a measure of the total amount of cholesterol types in the blood, determined by an overnight fast.
A blood test can measure cholesterol levels. Total cholesterol under 200 mg/dL is considered optimal. Borderline high is 200-239 mg/dL. Over 240 mg/dL is considered high. LDL cholesterol under 100 mg/dL is considered optimal, with over 160 mg/dL being very high. For HDL, over 60 mg/dL is considered protective against heart disease while under 40 mg/dL is a major risk factor.
What factors influence cholesterol levels?
Cholesterol production is a normal and essential process, but levels can become too high due to a combination of genetic and lifestyle factors. Factors that can increase cholesterol include:
– Diet – A diet high in saturated and trans fats found in fatty meats, full-fat dairy, fried foods, baked goods, and certain oils can raise cholesterol. Excess calories and obesity also contribute.
– Physical inactivity – Lack of exercise lowers HDL and contributes to weight gain.
– Smoking – Lowers HDL cholesterol while increasing LDL cholesterol and triglycerides.
– Heavy alcohol use – Increases triglycerides and blood pressure.
– Genetics – Genetic factors can impact how cholesterol is produced and removed from the body. Familial hypercholesterolemia is a genetic disorder that causes very high cholesterol.
– Diabetes and prediabetes – Having higher blood sugar levels makes you more likely to have abnormal cholesterol levels.
– Certain medications – Drugs that can raise cholesterol include anabolic steroids, progestins, corticosteroids and immunosuppressant drugs.
– Underactive thyroid (hypothyroidism) – May increase LDL cholesterol and lower HDL cholesterol.
– Kidney disease – Damaged kidneys cannot properly remove LDL cholesterol.
– Pregnancy – Hormone changes during pregnancy can increase cholesterol, especially triglycerides.
How is high cholesterol treated?
Treatment for high cholesterol focuses first on lifestyle changes such as:
– Following a heart-healthy diet low in saturated fat, trans fat, and cholesterol while high in fiber from fruits, vegetables and whole grains.
– Exercising for 30-60 minutes most days.
– Losing excess weight.
– Quitting smoking and limiting alcohol.
– Managing other health conditions like diabetes, hypothyroidism or kidney disease.
When cholesterol targets are not reached through lifestyle alone, cholesterol-lowering medications may be prescribed. First-line medications typically include:
– Statins – Block cholesterol production in the liver. Examples include atorvastatin (Lipitor), simvastatin (Zocor), and rosuvastatin (Crestor).
– Cholesterol absorption inhibitors – Block absorption of cholesterol from food. E.g. ezetimibe (Zetia)
– PCSK9 inhibitors – Help LDL receptors recycle back to the liver to remove more LDL from the blood. E.g. evolocumab (Repatha).
– Bile acid sequestrants – Bind to bile acids made from cholesterol. E.g. cholestyramine (Questran).
– Niacin – Helps lower LDL while raising HDL.
– Fibrates – Mainly lower triglycerides but can also decrease LDL particles.
Some new cholesterol medications being researched include thyroid hormone analogs, antisense oligonucleotides, microsomal triglyceride transfer protein inhibitors, and apoA-1 upregulators.
What is zinc?
Zinc is an essential mineral involved in hundreds of processes in the human body. It is naturally found in certain foods and also available as an oral supplement. Some key facts about zinc:
– Zinc is found in every cell and needed for proper cell division and growth.
– Over 300 enzymes in the body require zinc for normal function.
– Zinc plays vital roles in immune function, protein synthesis, DNA synthesis, and metabolism of fats and carbs.
– Good food sources include oysters, red meat, poultry, seafood, nuts, seeds, legumes, whole grains and dairy.
– The recommended daily intake is 8-11 mg per day for adults, with an upper limit of 40 mg per day.
– Zinc deficiency can occur with poor dietary intake, malabsorption disorders, alcoholism, diabetes, and other chronic illnesses.
– Deficiency symptoms include impaired growth, diarrhea, impotence, hair loss, eye and skin problems, impaired appetite, altered cognition, and immune dysfunction.
– Excessive zinc intake above the tolerable upper limit can interfere with copper absorption and alter LDL cholesterol.
What is the link between zinc and cholesterol?
Some research over the past few decades has suggested that getting enough zinc through the diet or supplements may help lower LDL (bad) cholesterol and total cholesterol. Here is an overview of the main scientific evidence so far on how zinc may impact cholesterol levels:
Animal studies
– Several older animal studies in rabbits, rodents and non-human primates have found that zinc deficiency tends to increase total cholesterol and LDL cholesterol.
– Giving supplemental zinc was shown to reverse this effect and lower cholesterol compared to deficiency.
– One study in rats showed that zinc supplementation for 6 weeks lowered total cholesterol by 29% and LDL cholesterol by 38% compared to controls.
– Research is still needed to confirm the direct mechanisms of how zinc status affects cholesterol metabolism in animals.
Human observational studies
– A cross-sectional study in over 4,000 US adults found that those in the highest zinc intake group (over 16 mg/day) had on average lower total cholesterol (by 9 mg/dL), LDL cholesterol (by 7 mg/dL) and triglycerides (by 14 mg/dL) compared to the lowest zinc group (under 9 mg/day).
– An Australian study in older adults found that plasma zinc levels were inversely correlated with total cholesterol, LDL cholesterol and triglycerides. Those in the highest zinc tertile had a 15% lower risk of high cholesterol compared to the lowest tertile.
– Not all observational studies have found a significant correlation between zinc intake, status and cholesterol levels however. Larger, higher-quality studies are still needed.
Human clinical trials
– Several clinical trials giving zinc supplements to adults have observed significant reductions in LDL cholesterol compared to placebo:
– One trial giving 50 mg of zinc per day found an average decrease in LDL of 10 mg/dL after 6 weeks.
– Another study using 30 mg of zinc for 12 weeks lowered LDL by 14 mg/dL.
– Doses of 135-150 mg per day for 1-3 months showed LDL reductions around 25 mg/dL.
– Meta-analyses combining data from these trials suggest that zinc supplementation for over 1 month significantly lowers total cholesterol by 8 mg/dL and LDL cholesterol by 12 mg/dL on average.
– Some studies have not found a significant effect on cholesterol however. More rigorous clinical trials are still needed, especially testing higher zinc doses for longer periods.
– Little effect on HDL (good) cholesterol has been observed. Trials on combining zinc with cholesterol medications are also lacking.
Possible mechanisms
Researchers hypothesize a few potential mechanisms for how higher zinc status could help lower cholesterol:
– May reduce cholesterol absorption by downregulating Niemann-Pick C1-like 1 protein.
– May inhibit cholesterol synthesis by reducing HMG-CoA reductase activity.
– May increase cholesterol breakdown by improving function of LDL receptors.
– May reduce inflammation and oxidative stress involved in atherosclerosis development.
– Effects are likely small however and more clinical studies are needed to expand on the mechanisms.
Does zinc supplementation lower cholesterol?
Based on the evidence so far, getting adequate zinc either through diet or supplements may offer a modest benefit for lowering LDL cholesterol. However, there are some important caveats:
– The effect sizes have been fairly small, with average LDL reductions around 5-15 mg/dL with zinc supplementation. Much more significant LDL reductions are seen with cholesterol-lowering medications and lifestyle changes.
– Some studies have not replicated this effect at all. More rigorous, large-scale clinical trials are still needed.
– Little to no effect has been observed with HDL cholesterol or triglycerides.
– It’s unknown if adding zinc provides any additional cholesterol-lowering benefit for those already taking statins or other cholesterol drugs.
– The optimal supplemental dose and formulation for reducing cholesterol is uncertain. Excess zinc above 40 mg/day can have adverse effects and may interfere with copper absorption.
– Increasing dietary zinc from foods like oysters, nuts, legumes, meat and dairy is likely preferable to supplements in those without deficiency. But foods also contain saturated fats that should be limited to control cholesterol.
– Other heart-healthy nutrients like soluble fiber, plant stanols/sterols, and soy protein have more consistently shown added benefits for cholesterol when combined with statins.
Overall, getting the recommended daily amount of zinc through a balanced diet is important for overall health, and may provide a small bonus for lowering LDL cholesterol. But relying on zinc supplements alone is unlikely to fix high cholesterol issues. Zinc is just one part of an overall lifestyle approach to maintain healthy cholesterol levels.
Who may benefit from extra zinc for cholesterol?
While benefits are likely modest overall, some groups may stand to benefit more from ensuring adequate zinc intake to optimize cholesterol levels:
– Those with obesity – Obesity can be associated with zinc deficiency along with higher LDL cholesterol and triglycerides. Ensuring adequate zinc status could offer a little extra benefit.
– Older adults – Many older adults fail to meet the recommended zinc intakes. Getting sufficient zinc from foods or a multivitamin may help maintain lower cholesterol levels.
– Those following plant-based diets – Vegans and vegetarians are more prone to zinc deficiency due to lower bioavailability from plant sources. Supplementation may provide small LDL-lowering benefits.
– Those with gastrointestinal disorders – Conditions like Crohn’s disease and ulcerative colitis increase risk of zinc malabsorption and deficiency. Correcting deficiency could help optimize cholesterol profiles.
However, the need for zinc supplementation should be determined individually in consultation with a healthcare provider, and not relied upon as a sole treatment for high cholesterol. Lifestyle changes, a heart healthy diet, exercise, and cholesterol medications if prescribed should form the basis of treatment.
Is zinc safe and effective for reducing cholesterol?
The benefits of supplemental zinc for high cholesterol appear modest at best, while risks can occur with excessive intake. When considering zinc supplements, keep these safety factors in mind:
– Stick to the recommended daily zinc intake of 8-11 mg for adults per day, unless a supplement is medically advised for a deficiency. Tolerable upper limit is 40 mg per day.
– Take zinc with food to minimize side effects like nausea. Take at least 2 hours before or after medications.
– Taking large zinc doses can interfere with copper absorption and alter HDL cholesterol levels over time.
– Zinc can interact with certain antibiotics like ciprofloxacin and tetracycline. It may also alter absorption of medications like penicillamine, antibiotics and diuretics.
– Large doses above 150 mg per day long term can negatively impact immune health and cholesterol ratios.
– Excess zinc intake is particularly risky for those with diabetes, HIV, autoimmune disorders, and certain cancers like prostate cancer.
– Zinc supplement quality matters – consumerlab.com tests brands for proper labeling and contaminant risks.
– If cholesterol levels remain uncontrolled with lifestyle changes alone, cholesterol medication is likely to provide much more significant benefits under a doctor’s care.
The best approach is to prioritize heart-healthy lifestyle choices first like diet, exercise, weight control, and stress management. Work with your healthcare provider to determine if you need cholesterol medication or have any nutritional deficiencies that may benefit from correction, including zinc status. Relying on zinc supplements alone is unlikely to fix high cholesterol issues.
Are there any risks or side effects of zinc related to cholesterol?
At recommended daily intakes, zinc is typically safe for helping maintain normal cholesterol levels. However, extremely high zinc intakes can potentially have adverse effects on cholesterol ratios:
– One study found that taking 150 mg per day of zinc for 6 weeks increased HDL cholesterol by an average of 8 mg/dL, which would normally be beneficial. However, it also increased LDL cholesterol by 15 mg/dL on average, making the overall ratio less favorable.
– Other studies using over 100 mg per day of supplemental zinc showed possible decreases in HDL cholesterol over time.
– Excessively high zinc supplementation above the 40 mg per day upper limit could potentially affect cholesterol balance negatively rather than positively over the long-term.
– One rare genetic disorder called acrodermatitis enteropathica causes improper zinc absorption and high LDL cholesterol. But zinc supplementation normalizes cholesterol levels in these patients when used to correct the severe deficiency.
– High-dose zinc may interfere with copper status, which is also needed for proper cholesterol metabolism as a component of enzymes. Ratios of these minerals are important.
Overall, there is little risk of negative effects on cholesterol or health with zinc intakes less than 100 mg per day from food and balanced supplements. But relying on zinc supplements alone in very high doses may backfire over time by altering HDL/LDL ratios. Moderation is key, and dietary sources of zinc are likely safest for long-term health.
Foods and meals to eat to increase zinc intake
Rather than relying solely on zinc supplements, getting adequate zinc from natural food sources should be the priority. Some of the best dietary sources of zinc include:
– Oysters – 6 medium oysters provide about 32 mg zinc, over 4 times the daily need. Oysters are the single greatest food source.
– Meats – Beef chuck roast, chicken, pork shoulder, and lamb provide between 5-7 mg zinc per 3-ounce serving.
– Beans – 1 cup of lentils, chickpeas, or baked beans provides 2-3 mg zinc.
– Nuts & seeds – 1 ounce of pumpkin seeds, cashews or almonds provides 0.8-1.3 mg zinc.
– Dairy – 1 cup of yogurt or cheese provides about 1-2 mg zinc.
– Eggs – 1 large egg has 0.6 mg zinc.
– Whole grains – 1 ounce of oats or wheat bran cereal has 0.5-0.8 mg zinc.
– Seafood – 3 ounces of crab or lobster has 2-3 mg zinc.
Some examples of meals providing good zinc sources:
– Baked salmon + 1/2 cup lentils + 6 small oysters = 8-11 mg zinc.
– 3 ounces sirloin steak + 1 ounce cashews + 1 cup milk = 6-8 mg zinc.
– Veggie burger patty + veggie chili with beans + pumpkin seeds = 5-7 mg zinc.
Conclusion
In conclusion, current research indicates that getting adequate zinc through balanced dietary sources may provide a small reduction in LDL (bad) cholesterol for some people, especially those at risk of zinc deficiency. However, the effect is unlikely to be dramatic or make up for poor diet and lifestyle habits. Relying too heavily on zinc supplements to lower cholesterol comes with potential risks if doses exceed 40 mg per day. For managing cholesterol, lifestyle approaches like heart-healthy eating, regular exercise, weight control, and avoiding smoking remain foundational. Work with your doctor to assess if you may benefit from cholesterol medication or correction of any nutritional deficiencies like zinc. Achieving recommended daily intakes from zinc-rich foods like oysters, meat, nuts and legumes is likely the best nutritional approach for long-term cardiovascular protection.
