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ObjectiveIt is well known that total cholesterol becomes less of a risk factor or not at all for all-cause and cardiovascular (CV) mortality with increasing age, but as little is known as to whether low-density lipoprotein cholesterol (LDL-C), one component of total cholesterol, is associated with mortality in the elderly, we decided to investigate this issue.Setting, participants and outcome measuresWe sought PubMed for cohort studies, where LDL-C had been investigated as a risk factor for all-cause and/or CV mortality in individuals ≥60 years from the general population.ResultsWe identified 19 cohort studies including 30 cohorts with a total of 68 094 elderly people, where all-cause mortality was recorded in 28 cohorts and CV mortality in 9 cohorts. Inverse association between all-cause mortality and LDL-C was seen in 16 cohorts (in 14 with statistical significance) representing 92% of the number of participants, where this association was recorded. In the rest, no association was found. In two cohorts, CV mortality was highest in the lowest LDL-C quartile and with statistical significance; in seven cohorts, no association was found.ConclusionsHigh LDL-C is inversely associated with mortality in most people over 60 years. This finding is inconsistent with the cholesterol hypothesis (ie, that cholesterol, particularly LDL-C, is inherently atherogenic). Since elderly people with high LDL-C live as long or longer than those with low LDL-C, our analysis provides reason to question the validity of the cholesterol hypothesis. Moreover, our study provides the rationale for a re-evaluation of guidelines recommending pharmacological reduction of LDL-C in the elderly as a component of cardiovascular disease prevention strategies.

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For half a century, a high level of total cholesterol (TC) or low-density lipoprotein cholesterol (LDL-C) has been considered to be the major cause of atherosclerosis and cardiovascular disease (CVD), and statin treatment has been widely promoted for cardiovascular prevention. However, there is an increasing understanding that the mechanisms are more complicated and that statin treatment, in particular when used as primary prevention, is of doubtful benefit. Areas covered: The authors of three large reviews recently published by statin advocates have attempted to validate the current dogma. This article delineates the serious errors in these three reviews as well as other obvious falsifications of the cholesterol hypothesis. Expert commentary: Our search for falsifications of the cholesterol hypothesis confirms that it is unable to satisfy any of the Bradford Hill criteria for causality and that the conclusions of the authors of the three reviews are based on misleading statistics, exclusion of unsuccessful trials and by ignoring numerous contradictory observations.

The homocysteine theory of arteriosclerosis was discovered by study of arteriosclerotic plaques occurring in homocystinuria, a disease caused by deficiencies of cystathionine synthase, methionine synthase or methylenetetrahydrofolate reductase. According to the homocysteine theory, metabolic and nutritional abnormalities leading to elevation of plasma homocysteine cause atherosclerosis in the general population without these rare enzymatic abnormalities. Through studies of metabolism of homocysteine thiolactone, the anhydride of homocysteine, in cell cultures from homocystinuric children, the pathway for synthesis of sulfate was found to be dependent upon thioretinamide, the amide formed from retinoic acid and homocysteine thiolactone. Two molecules of thioretinamide form the complex thioretinaco with cobalamin, and oxidative phosphorylation is catalyzed by reduction of oxygen, which is bound to thioretinaco ozonide, by electrons from electron transport particles. Atherogenesis is attributed to formation of aggregates of homocysteinylated lipoproteins with microorganisms, which obstruct the vasa vasorum during formation of arterial vulnerable plaques.

Within the past four decades, the efforts of investigators worldwide have established the amino acid homocysteine as an important factor in arteriosclerosis and diseases of aging. After its discovery in 1932, homocysteine was demonstrated to be an important intermediate in the metabolism of amino acids. However, little was known about the broader biomedical significance of homocysteine until 1962, when children with mental retardation, accelerated growth, dislocated ocular lenses, and frequent vascular thrombosis were found to excrete homocysteine in the urine. My study of two patients with homocystinuria caused by different inherited enzymatic disorders in 1968 disclosed advanced widespread arteriosclerotic plaques in both cases. This discovery led to the conclusion that homocysteine causes vascular disease by a direct effect on the cells and tissues of the arteries. This interpretation suggests that homocysteine is important in the pathogenesis of arteriosclerosis in persons with hereditary, dietary, environmental, hormonal, metabolic, and other factors predisposing them to hyperhomocysteinemia. Within the past decade, many major clinical and epidemiological studies have proven that hyperhomocysteinemia is a potent independent risk factor for vascular disease. According to the homocysteine theory of arteriosclerosis, insufficient dietary intake of the B vitamins, folic acid and pyridoxine, caused by losses of these nutrients during processing of foods, leads to elevation of blood homocysteine and vascular disease in the general population. The dramatic decline in cardiovascular mortality since the 1960s in the United States is attributed to fortification of the food supply by synthetic pyridoxine and folic acid. The recent Swiss Heart Study showed that B vitamins slowed restenosis in patients with coronary arteriosclerosis treated with angioplasty. Currently, more than 20 prospective, worldwide, interventional trials involving at least 100,000 participants are examining whether lowering plasma homocysteine levels with supplemental B vitamins will prevent mortality and morbidity from arteriosclerotic vascular disease.

Four ‘master’ strains of Aspergillus nidulans, three of which are marked on each of the eight chromosomes, are used for assigning genes of unknown location to linkage groups. In this technique a heterozygous diploid is synthesized between one ‘master’ strain and a strain carrying an unlocated marker. This diploid is haploidized by growth on p-fluorophenylalanine, and the haploids thus obtained are classified for recombination between the unlocated marker and each of the markers of the ‘master’ strains. The marker or markers of the ‘master’ strain which show no recombination with the unlocated marker identify the chromosome pair on which the latter is located. One example is presented for each of the four ‘master’ strains.

In mid-20th century United States, deaths from vascular disease reached a peak incidence in 1955, but little was known about the underlying causes of this epidemic of disease. The significance of homocysteine in human disease was unknown until 1962, when cases of homocystinuria were first associated with vascular disease. Analysis of an archival case of homocystinuria from 1933 and a case of cobalamin C disease from 1968 led to the conclusion that homocysteine causes vascular disease by a direct effect of the amino acid on arterial cells and tissues. The homocysteine theory of arteriosclerosis attributes one of the underlying causes of vascular disease to elevation of blood homocysteine concentrations as the result of dietary, genetic, metabolic, hormonal, or toxic factors. Dietary deficiency of vitamin B-6 and folic acid and absorptive deficiency of vitamin B-12, which result from traditional food processing or abnormal absorption of B vitamins, are important factors in causing elevations in blood homocysteine. Numerous clinical and epidemiologic studies have established elevated blood homocysteine as a potent independent risk factor for vascular disease in the general population. Dietary improvement, providing abundant vitamin B-6, folic acid, and cobalamin, may prevent vascular disease by lowering blood homocysteine. The dramatic decline in cardiovascular mortality in the United States since 1950 may possibly be attributable in part to voluntary fortification of the food supply with vitamin B-6 and folic acid. Fortification of the US food supply with folic acid in 1998, as mandated by the US Food and Drug Administration, was associated with a further decline in mortality from vascular disease, presumably because of increased blood folate and decreased blood homocysteine in the population.