Can Chlorella Stop Eggs From Raising Cholesterol?

Oct 17, 2026 · caesar langcat

Eat three eggs a day for a month and your cholesterol will most likely go up a little. A team of researchers in Seoul wanted to know if  Chlorella could stop that from happening.

And it largely did! In their 2016 study, young adults who took chlorella with their eggs saw their LDL cholesterol rise by just 1.7%. Those who took a dummy pill saw it rise by 14.3%. Chlorella held back close to 90% of the increase.

It was a small study, with 34 people, so it’s worth looking closely at how it was done and what other research says.

What is chlorella?

Chlorella is a tiny green alga. Each one is a single cell, far too small to see without a microscope. It grows in fresh water and is sold dried, as a dark green powder or pressed into tablets.

People take it because it’s rich in protein, vitamins and natural plant pigments. One of those pigments is lutein, the same yellow pigment that colours egg yolks. The daily dose in this study, 5 grams or 12 small tablets, contained about 3 grams of protein.

The researchers used Chlorella vulgaris, the type you’ll find most often in shops.

What did the researchers do?

The researchers, from Ewha Womans University in Seoul, signed up 34 healthy young adults with normal cholesterol. Most were women in their early twenties.

For four weeks, everyone ate three eggs a day: one at breakfast, one at lunch and one at dinner. That added 510 mg of cholesterol a day, about three times what they normally ate.

With each egg, they also swallowed four tablets. Half the group got chlorella. The other half got look-alike tablets made of milk sugar, known as a placebo. A random draw decided who got which, and neither the volunteers nor the researchers knew until the end. This is called a double-blind randomised trial, and it’s the most reliable way to test a supplement.

Everyone had a blood test on an empty stomach before and after the four weeks. They stuck to the plan well: on average, people took 97.5% of their tablets.

What happened to their cholesterol?

The eggs did what the researchers expected. In the placebo group, total cholesterol went up by about 10% and LDL cholesterol by about 14%.

LDL is the type of cholesterol that can build up in the walls of your arteries, which is why it’s often called “bad” cholesterol. In the chlorella group, LDL hardly moved. It went up by just 1.7%.

The gap between the two groups was big enough that it’s very unlikely to be a fluke. Scientists call that statistically significant.

Changes after four weeks, as reported by the authors (Kim et al., 2016).

In actual numbers, total cholesterol in the placebo group went from 4.24 to 4.71 mmol/L (164 to 182 mg/dL). In the chlorella group it went from 4.38 to 4.47 mmol/L (169 to 173 mg/dL). Everyone stayed within the healthy range.

HDL, the “good” cholesterol, went up in both groups. The authors report a bigger rise with chlorella, but that difference could be down to chance.

Chlorella also left a clear trace in the blood. Alpha-carotene, an orange pigment chlorella contains, roughly tripled in the people who took it. The researchers think it could be used to see who responds to chlorella.

The authors concluded that chlorella may help keep cholesterol at a healthy level in people who eat a lot of fatty food, and so help prevent or delay the risk of heart disease.

How Could Chlorella Block Cholesterol?

The most likely explanation is that chlorella stops some of the cholesterol in your food from being absorbed. Instead of ending up in your blood, more of it leaves your body with your stool.

This idea comes from studies in rats. The egg study in people didn’t measure how chlorella works.

• In a 2008 study, rats on a high-fat diet got chlorella mixed into their food (5% or 10% of it). They passed more fat and cholesterol in their droppings. At the higher dose, the cholesterol in their blood was lower too.
• In a 1988 study, rats fed extra cholesterol were given fatty compounds taken from chlorella. These held back the rise in blood cholesterol about as well as whole chlorella powder, and the rats got rid of more cholesterol.
• Other researchers point to the fibre in chlorella, which may bind to fat in the gut.

The rats got far more than people do. If chlorella made up 10% of what a person eats, that would be roughly 40 to 50 grams a day, about eight to ten times the dose in the egg study.

Do other studies agree?

Partly. Most reviews of human studies find that chlorella lowers cholesterol a little. One recent review found no effect at all.

The same team’s earlier study. In 2014, the Seoul researchers gave 63 adults with slightly high cholesterol either 5 g of chlorella or a placebo for four weeks. Total cholesterol fell 1.6% with chlorella. Triglycerides, another type of blood fat, fell 10.3% with chlorella and rose 11.9% with the placebo.

Reviews that combine many studies. These are called meta-analyses.

• 2018: 19 studies, 797 people. Chlorella lowered total cholesterol by about 9 mg/dL and LDL by about 8 mg/dL on average. It worked better in people with health problems than in healthy people.
• 2022: 10 studies, 539 adults. Total and LDL cholesterol both dropped by about 7.5 mg/dL. Only two of the studies checked what was actually in the chlorella they used.
• 2025, Algal Research: lower total and LDL cholesterol and higher HDL with chlorella.
• 2025, Nutrients: 12 chlorella studies, with no clear effect on blood fats or blood pressure.

What are the weak points of this study?

• It was small. 34 people started and 29 finished.
• It was short. Four weeks tells us nothing about what happens over months or years.
• The volunteers were all alike. They were healthy young Koreans, and 30 of the 34 were women. Older people, men, or people with high cholesterol may respond differently.
• A chlorella company helped pay for it. Daesang, a Korean chlorella maker, supplied the tablets and a grant. The authors say the company had no say in the results.
• It measured cholesterol, not heart attacks. Lower cholesterol usually means lower risk, but this study can’t show that directly.
• Triglycerides went missing. They were measured but not reported.

What does this mean for you?

• If you eat a lot of eggs: in this study, three eggs a day raised cholesterol only modestly, and it stayed within the healthy range. Chlorella kept most of that rise in check.
• If you’re thinking about chlorella for your cholesterol: across all studies so far, the effect is small and the results are mixed. The dose tested most often is 5 g a day.
• If you have high cholesterol or take medication for it: no study has tested chlorella as a replacement for treatment. Talk to your doctor before you change anything.

Frequently asked questions

How much chlorella did people take?

5 grams a day: 12 small tablets, four with each meal. The same team used the same dose in their earlier study.

How much do eggs raise cholesterol?

In this study, three eggs a day raised total cholesterol by about 18 mg/dL (0.47 mmol/L) in four weeks. That fits with older research on how much cholesterol from food adds to cholesterol in the blood. Everyone stayed within the healthy range.

How long does chlorella take to work?

Both Korean studies saw a difference after four weeks. No study has followed people for years.

Can chlorella replace cholesterol medication?

No study has tested that. The average drop in LDL seen with chlorella, about 8 mg/dL, is much smaller than what medication usually achieves. Don’t stop your medication without talking to your doctor.

Chlorella or spirulina: which is better for cholesterol?

Nobody has compared them directly. A 2025 review of both found a small blood pressure benefit for spirulina and no clear effect on blood fats for chlorella. Other reviews did find a small cholesterol drop with chlorella.

Did anyone get side effects?

No one in the egg study reported serious side effects during the four weeks. Quality varies between brands, so choose one that’s tested for heavy metals such as lead and mercury.

Sources

1. Kim S, Kim J, Lim Y, Kim YJ, Kim JY, Kwon O. A dietary cholesterol challenge study to assess Chlorella supplementation in maintaining healthy lipid levels in adults: a double-blinded, randomized, placebo-controlled study. Nutrition Journal. 2016;15:54. PubMed Central DOI
2. Ryu NH, Lim Y, Park JE, et al. Impact of daily Chlorella consumption on serum lipid and carotenoid profiles in mildly hypercholesterolemic adults. Nutrition Journal. 2014;13:57. PubMed Central
3. Fallah AA, Sarmast E, Habibian Dehkordi S, et al. Effect of Chlorella supplementation on cardiovascular risk factors: a meta-analysis of randomized controlled trials. Clinical Nutrition. 2018;37(6 Pt A):1892–1901. PubMed
4. Sherafati N, Bideshki MV, Behzadi M, et al. Effect of supplementation with Chlorella vulgaris on lipid profile in adults: a systematic review and dose-response meta-analysis of randomized controlled trials. Complementary Therapies in Medicine. 2022;66:102822. ScienceDirect
5. Shiri H, Talebi Taheri A, Soleimani AA, et al. Chlorella supplementation diminishes cardiovascular risk factors in adults: a GRADE-assessed systematic review and meta-analyses of randomized clinical trials. Algal Research. 2025:104281. ScienceDirect
6. Pinto-Leite M, Martins D, Ferreira AC, et al. The role of Chlorella and spirulina as adjuvants of cardiovascular risk factor control: a systematic review and meta-analysis of randomised controlled trials. Nutrients. 2025;17(6):943. MDPI
7. Kwak JH, Baek SH, Woo Y, et al. Beneficial immunostimulatory effect of short-term Chlorella Nutrition Journal. 2012;11:53. Springer (lipid result as summarised in this systematic review)
8. Lee HS, Park HJ, Kim MK. Effect of Chlorella vulgaris on lipid metabolism in Wistar rats fed high fat diet. Nutrition Research and Practice. 2008;2(4):204–210. PubMed Central abstract
9. Effect of lipophilic extract of Chlorella vulgaris on alimentary hyperlipidemia in cholesterol-fed rats. Artery. 1988;15(4):217–224. PubMed